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'[SX] Fuel Injection'
2007\05\23@145721 by markistuffn/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, markistuff wrote:

The SX chip is amazing.  First off I would like to thank everyone who posts to the forums here,  huge amount of info is here and it has helped me out so much doing my little project.  I have a little dunbuggie/gokart with a twin  840 cc engine on it.  the carb on it was really really bad,  so i had the bright idea, "why dont i put fuel injection on it",  so after about 2 weeks of work  ive got it up and running,  still kindof in the testing stage but the sx chip is running the engine!  it reads from all the sensors then calculates the correct amount of fuel to inject.  this is the first project ive really ever built with the sx/28 or any microcontroller for that.  just keep up the good work on the forums,  they answered alot of my questions.  ill post some more photos in a few days once i get all the wires cleaned up and everything looking nice. but this is the ECU

Mark
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2007\05\23@163616 by CCraign/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, CCraig wrote:

That's pretty cool.

I would have no idea on how to control a FI motor. (I guess that makes me old school)
Some guys were talking about this very thing on the BS2 forum.

http://forums.parallax.com/forums/default.aspx?f=5&m=190087
Maybe you should go show them how it's done. I'd like to see more detail too. (looking to change schools)
Nice work
Chris
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2007\05\23@180825 by williamn/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, william wrote:

I think 75Mhz is too fast ( overkill ).
How about posting the schematics for SXers who know nuts about ECU?

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2007\05\23@182102 by PJMontyn/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, PJMonty wrote:

William,
Since you feel that 75 MHz is overkill, I'm curious what speed you ran the clock at on the fuel injection control unit you designed?  Have you designed many of them before, or just one?

Thanks,
PeterM
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2007\05\23@184414 by williamn/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, william wrote:

PJMonty,
If you read my post, I have already noted that I have never designed an ECU before.
The 75Mhz being too fast is just my opinion, I could be wrong.

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2007\05\23@223855 by markistuffn/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, markistuff wrote:

Bad on me but i never did draw up a scmaic, i just design it strait to the pcb layout.  figured i would skip a step to speed up the prosses.

but what is on it is basicly 4 MOSFET Drivers, 2 for driving the injectors and 2 for the coils that go to the sparkplugs.


has a 4K memory for storing errors/ tunning variabls

2 a/d converters,  one is for 0-5 volts the other is 0-2.5 on the 2.5 volt i run:

- 2 temperature sensors, one for manifold air temp the other for engine temp
- O2 sensor input on the 5V:

- TPS sensor (a pot hooked up to the throttle)
- Map sensor

and i have extra inputs for anything i want to add later use the "poor mans searil in/out http://forums.parallax.com/forums/default.aspx?f=7&m=171998&g=172419#m172419

and i have 2 hall sensors, on on the crank and one on the cam

i used to voltage reguators,  KA317 to drop it to 8.5 volts , i used that for driving serial port output.  and from 8.5 i use the LM2940 to bring it down to the 5v and before it all thier is a 4001 dioide for protection/help drop the voltage some more.   probably a bad way of doing things but im new at this

its still in the building prosses, but i wrote a simple program that gets the engine to run and uses the O2 sensor to set the correct air fuel ratio. this isnt the final program, it still needs alot of work. and features to add to it.   and if thiers any programing sugestions/ enhansments that would be appresated. only been using this stuff for alittle over a month, pretty steep learning curve :shakehead:  


im not sure if 75 Mhz would be over kill or not but i did run some "benchmarks"  with the chip doing a bunch of calcuations looping, and i figured that 75 would be right, sould beable to handle about 14000 RPM just for running the fuel injectors, perfect for my motocycle :cool:  ,  but this engine its being built for shouldnt run past 5000rpm.   i plan on adding alot more of a load to the prossesor,  haveing it also control the spark advance.  drive a lcd display with the engine temp and rpm  load  etc.  and i also want to be able, while its running, to connect to a computer by serial port so that i can tune it or adjust things while its running.

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2007\05\24@003230 by williamn/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, william wrote:

I don't see any TO-220 mosfets on the board.  Are they on another board?

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2007\05\24@003507 by PJMontyn/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, PJMonty wrote:

William,
I guess I misunderstood.  You seemed so certain that 75 MHz was overkill that I figured you must have designed an ECU before.  I mean, how else would you know with such certainty unless you had done it before?  When you referred to "SXers who know nuts about ECU," I assumed you must mean the other people on this forum who had no ECU experience.  My mistake.

I guess you include yourself in the group of SX'ers who know "nuts" about ECUs.  If that's true, I'm curious what lead you to the conclusion that 75 MHz was too fast?  My personal rule of thumb when I have absolutely no knowledge on a topic is to ask a question instead of making a statement.  For example, I wouldn't have said, "I think 75Mhz is too fast ( overkill )."  I would have asked a question like, "I'm curious why you're running the ECU at 75 MHz."
Thanks,
PeterM
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2007\05\24@010835 by williamn/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, william wrote:

Dear Monty,
Are you trying to pick a fight with me?  If you are, please say so.
I may have given my opinion without all the formalities, protocol or niceties...  but that's what I am, not a politician.
Your efforts to ridicule my opinion given in ernest to help with the board design is itself not very diplomatic.

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2007\05\24@055205 by williamn/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, william wrote:

Mark,
The reason why you need 2 regulators is because your board uses too much 5V current.
My estimate of your ECU's 5V current consumption is 170 - 220mA.

This may overheat the power regulators if you put the board into a casing without forced convection or heat sink.
Putting the 2 regulators so close together is also a bad idea, considering the heating.

My humble advice would be to run the SX at 20Mhz instead.
This will drop your total (whole board) 5V current consumption to less than 50mA, then you only need one 5V regulator without a need for any heatsink.

I assume you must be using assembly for this project, b'cos if you use SX/B, it would be difficult to talk to a PC while managing the engine in real time.  So at 20Mhz or 20 MIPS, running an engine at 10,000 rpm, you will get 2000 instructions per engine revolution, which I think is a workable proposition.

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2007\05\24@071924 by John Bondn/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, John Bond wrote:

Dear William Chan
I would gladly pick a fight with you, anytime, and I'm probably 20 years older than you are. I inadvertently killed another guy 17 months ago. The second in this long life of mine. You see, when I did my unarmed combat training in the notorious SADF, they never taught me to hurt a person so  death is usually quite quick. (Our laws are a bit looser here in South Africa and the crime is called manslaughter, in both cases involuntary and I was unarmed while the agressor was armed so no charge has been made. Yes, I am not seeping much at night and I have another serious case of depression)
Now Chan, this site usually operates with a high level of civility. Most of the geeks round here use brains, not muscle. The only reason a psychopath like me is allowed on the site is that I live in Darkest Africa at the bottom of the world far away from the USA.

So please would you be a good little boy, apologize to the civilized Mr Monty, and while you're at it, GET A REAL BIKE...

OH and to the other users, be careful what you post. That slightly slow and simple old Blogger (or is it bugger) isn't always everything he appears to be...

John Bond
Military Service No 685 24 586BT
Unit - SA Army Loss Control Unit
Awards - SA Army Good Service Medal - Bronze, Pro Patria with Cuneni Clasp
Rank 1st Lieutenant, Previously Sergeant in the artillery
Served under the notorious Major Hopeful in both the Angolan and Namibian/SWA wars
Mustering, sharp shooter.

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2007\05\24@072411 by robotworkshopn/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, robotworkshop wrote:

From the specs it sounds more like Mark is using two voltage regulator because he wants two different voltages (8.5v and 5v).  It might simplify things a bit to use a Serial driver like a MAX232 and just use a single 5v regulator for the project.  I haven't seen any mention of the actual current used by the project and although running the SX at 75Mhz is supposed to take a bit more current it may not be an issue at all for this particular project.  I don't see where 220ma should be too much for an LM2940.  For sizing the voltage regulator required you'll also have to factor in all the other parts on the board that also use the 5V supply.  The idea of using a diode to drop the voltage a bit before it goes into the voltage regulator isn't a bad idea at all (as long as it is sized to handle the current) since it offers the added benefit of reverse polarity protection.  If you connect the power backwards you won't fry it!

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2007\05\24@105259 by Ibsenn/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, Ibsen wrote:

That is awesome !!!!

I have been thinking about building a ECU for a long time...
Way to go ! This is quite an accomplishment !

I think I will be using the Propeller for my project. But that will not be any time soon !!!

I am very interested in your project and would like if you keep
posting you progress and documentation...

How about a video of the motor running   :jumpin:

Geek the fuel spraying and the sparks flying !!!

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2007\05\24@113956 by bennettdann/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, bennettdan wrote:

Markistuff,
   I am working on an ECU controller myself and would like to help out any way I can, I plan to use the SX48 because of the internal Timers I think will be better for PWM control so I have been told. I have a chevy truck with a V6 in it I plan to use as a test bed. I will this weekend get out my Oscope and trace the various signals on the fuel injectors and other sensors and use that info to help design it. The megasquirt sight has lost of info on teh HEI distribitor in my truck and how to make the timming advanced work. I like your ECU and would be able to help you out with a VB.net program to tune your controller I plan to make my VE table be a 12 *12 and the timing a 12*12 also then I can make changes to the VE table on my laptop and then send them to the SX also I will set my table up so you can see where the PWM and Timming curve is at in real time. Hope I can be a helping hand.

A question, you say you have the engine running but does it just idle or will run throught the entire engine RPM?
Also have you thought about using a wideband O2 sensor?

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2007\05\24@115100 by beann/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, bean wrote:

Yes the SX48 would probably be the better choice because of the two internal 16 bit timers.

Bean.

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2007\05\24@122047 by johncouturen/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, johncouture wrote:

Mark,
What program did you use to draw the board above?  Doesn't it have a schematic option?

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2007\05\24@142938 by bennettdann/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, bennettdan wrote:

Bean,
The distribitor on the engine I have has a hall sensor pusle output of 6 pulses per revolution and has an input that accepts a PWM input that is used to fire the coil to the spark plug. What the OEM ECU does is it take the Hall input pulse then Dwells that then sends out a pulse to the coil so that it will fire the next sparkeplug inline thats how you can change the timming advance on your motor.

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2007\05\25@000528 by markistuffn/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, markistuff wrote:

I tryed uploading a video clip of it running but the forums would let me, so i posted it on youtube.  heres the link.



William Chan - i didnt use any TO-220 package mosfets,  i got them in the 8pin dip style,  only because that was all that was in stock were i got it.


John Couture - i used pcb wizard to make the silkscreens or whatever their called for etching.  i looked and thier isnt a way to convert the pcb layout to a circiut design

bennettdan - as to the wideband o2 sensor, i could have put one on but i was trying to save some money.  but my brother wants me to build him a device that used the wideband o2 sensor and you put it in the exsause and it shows you on a lcd screen what air/fuel ratio the car is.  he wants to tune the carbs on his cobra.   when i said i have it running, it will idle perfectly, and once i added in the coding to increase the pulswidth when you hit the gas it is very responsive.  but right now for some reason it will not hold a high rpm without backfireing alot.  not to sure whats causing that.  its running the stoikiometric(how ever you spell it) 14.7 to 1, well at least the o2 sensor says it is.  i think that my ignition is way out of wack,  to much advance.  its still running off the old ignition system not my ecu. i figured only work with one part of the system at a time so its easer to get all the bugs out.


on the little white breadboard i put some lcds for debugging,  the video is pretty crappy i know but one will turn on when the engine is warm,  then i have two one that turns on when the O2 sensor says its lean, so the computer makes it richer and visvera,  does what its supost to,  jump back and forth between the two really quickly when its running the right mixture.


i guess next is figure out if its my ignition or the fuel injection that is causing the backfiring, then from thier i can get the info to make the VE tables.  bennettdan, im not sure if it would be better to have tables made and stored in the eeprom or just let the sx calcuale it out based on some predetermined verables?

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2007\05\25@005558 by williamn/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, william wrote:

Is the NIC4422 directly driving the fuel injectors?
I thought they are Mosfet drivers only, ie. they are supposed to drive larger mosfets.

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2007\05\25@015317 by John Bondn/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, John Bond wrote:

What a fascinating project!!!

The way I understand it, there are a number of factors affecting your fuel flow in a motor. In an ideal engine management system, I guess these would be:

-        Throttle setting, The wider the throttle the greater the fuel flow
-        RPM, The higher the speed, the greater the flow. This is probably not
               linier because low RPM, wide throttle, heavy torque needs a good flow
-        Acceleration, you need a spurt as you open the throttle. The quicker
               you open it the bigger the spurt, (remember the tuners rule - run
               engine rich on acceleration)
-        Temperature of the air, atmospheric pressure and humidity.

-        Temperature of the motor. Remember the bigger the difference
               between engine temperature and inlet air temperature, the more air the
               engine breaths so you need a bit more fuel
-        Valve timing, the more aggressively the exhaust valve opens the more
               fuel you need. Trouble is this is not uniform over the full RPM range but
               varies depending on the harmonics on the exhaust valve and the
               exhaust manifold. The same is true on the inlet valve.

-        Engine condition, compression, wear, how clean the air filter and plug
               are, etc
-        Quality of fuel, RON number (for knock) and calorific value (power of
               the fuel), how well it atomizes. (probably not a problem in the USA)
Now obviously you're not building an Indy 500 engine so a lot of these can be left out. I have two questions:

Is it possible to address most of these by monitoring only throttle, RPM, temp and CO2?
If you were to add sensors, what would they be?

To think you're doing all this with just 1 microprocessor chip!!! All the new commercial systems I've seen seem to favor one controller for ignition, one for injectors one for peripheral components, (and often one specifically for the gear box!!!).All this is tied together with LinBus or some bastardized CanBus.

John Bond
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2007\05\25@085648 by markistuffn/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, markistuff wrote:

I did some reading and i think i figured out why its backfireing, ill test it out later today to see if it fixes the problem.

william chan -  yes the nic4422 is directly driveing the injectors.  not till you pointed itout did i realize they are fore driving the mosfets, miss read the data sheet, put they are supost to handle 9 peak amps and about 2 hold amps, thats plenty for driving ingectors and ignition so i think ill be ok running that.  the reson why i picked them is they were some of the first that showed up in the parts search and they could run off logic level and handle a fair amount of current.  
John bond - you asked if its possable to get the pulsewidth from monitoring only the throttle, RPM, temp and O2.  yes you can, but it wont be near as good as haveing a map sensor to detect the manifold abu(expletive)e pressure.  with out a map or maf, it will inject a pre determind amount according to throttle and rpm, but it dosnt account for engine load and altitude.  so the o2 sensor will work away to correct the ratio( a narrow band O2 sensor only works a low rpm.  thats the problem i think i had, at high rpm my engine leans out and back fires)  so for sudden changes in opporating conditions it wount work as good.  but detecting the air comming into the engine gives a pretty good indication of whats going on therefor it can adjust the pulswidth accordingly.  well as far as i understand.

 if i were to add sensors it would be a humittity sensor.  it would help out in calcuatling air comming into the engine. thats probably about it
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2007\05\25@121824 by johncouturen/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, johncouture wrote:

Ok gang,
Some days I just have too much time on my hands (grin).

Anyway, here is a stab at Mark's board.  Attached are the schematic, a new board layout and a parts list.

Many, many more things need to be done to it and there are errors in it because there are places where I could not figure out where the traces went.

I did the board in Eagle 4.16r2.  This is a freeware program that allows you to make up to 80 x 100 mm boards.  The fancy thing about this is the autorouter which I'm sure Mark will appreciate because once you create the schematic and roughly place stuff on a board, the computer figures out how to get the traces to the components.  Program is available at http://www.cadsoft.de/  Note that the learning curve is a little steep but well worth it!

My design skills are minimal so please check the following:

1) Connectors may be upside down.  I still haven't figured out which way is up.

2) cross signal interference.  I laid out the board to make it look pretty.  That may not work in real life when you have high frequency signals near other signals.  Someone needs to double check that.

3) Obviously, Mark needs to look it over and determine if I am even close!

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2007\05\25@132921 by markistuffn/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, markistuff wrote:

WOW, thats pretty impressive to draw up the scmatics  i looked them over and fixed the wiring.  you were very close to the design.  the blue on the picture is to break or getride of the wires/connections and the black is to make new connections.  

I had a problem programing it for a while. would say sxchip communication failed.  looked round and it was sugested to put a small cap really close to the vdd and vss pins.  so on the reverse side i sodered a .22uf cap on the pins of the connector and now it works great.


Eagle sounds like a good program, ill have to give it a try.  heres the files back
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2007\05\25@161805 by bennettdann/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, bennettdan wrote:

markistuff,
  The backfiring my be comming from your ignition the ignition can be converted over to the 4 prong HEI module and controls spark advance very well the megasqurit has some wiring details for that modification on the forum..
Also most injectors are wired with a 5amp inline fuse the high side so the mosfet drivers may not be driving the injectors correctly and might cause some of the high RPM backfire problems...when a mosfet gets hot is does not flow current as well
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2007\05\25@200724 by johncouturen/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, johncouture wrote:

Mark,
Thank you for looking it over.  I've attached the files so you can start playing around with it in Eagle.  Presumably the goal for this is to produce a PCB that others can easily duplicate (i.e. a group project).  A couple of questions:

1) you mentioned that Q3 is a A1015 transistor.  The pinout is different (ECB vs EBC) than the 2N3906 and the A1015 is not in the symbol library.  Do you want to keep it as a 3906 as I have it so that people will not have difficulty finding that part?

2) again note the orientation of the connectors.  I flipped AN1 in the schematic to match the way you have it on your board.  I am not sure if orientation of others are critical or is it just a matter of getting used to the way it is.

3) Datasheet recommends EEPROM address lines to ground and not left floating, so I grounded them.

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2007\05\26@005911 by Capt. Quirkn/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, Capt. Quirk wrote:

Is it possible to address most of these by monitoring only throttle, RPM, temp and CO2?

Why would do think you need so many?

Don't need CO2 if you have the other 3
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2007\05\26@030820 by williamn/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, william wrote:

Mark,
Since bennettdan has also suspected insufficient drive coming from the 4422s, why don't we change the design to use IRL510 mosfets which can be driven at logic level ( 5v ) and can handle more than 5 amps continuous.
They cost less than USD 1 each.
If you put the TO-220 mosfets standing up, they actually use less PCB space than the DIPs.

What is the SR8 port used for?

John,
How about extending the board to cater for 4 cylinder car engines as well.
This way, we can pool PCB resources and make more boards in one go for more people.

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2007\05\26@085714 by bennettdann/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, bennettdan wrote:

Capt. Quirk,
   You dont need the O2 sensor to make a ECU work but then its a speed density unit and its only as good as the tune you install in the ECU and unless you have a dyno to make full power then using the O2 sensor will keep it in the optimal 14.7 to 1 ratio with a regular o2 sensor but the real power is made with about 12.5 to 1 or 13 to 1 AFR in most performance engines so a wide band O2 will make the most HP in theary...For most of us going to a Dyno is not an easy and the O2 sensor will make the motors run pretty good.

markistuff,
   I really think that the small mosfet drivers you have are not up to the job.I like the IRL510 and should work very nice and I would even add a heatsink to handle heat. You can parrallel two of the mosfets together and up your available current handling and also one good thing about parralleling two mosfets together is that if one gets a little to hot and wont conduct as much the other will take over and let the first one cool and that way you never will be shy of the current you need. The only other thing I might suggest is the reason why I plan to use the SX48 is that the PWM the SX28 generates is not the best for a motor or solenoid this might be causing you some headache, do you have acess to a Oscope to check any of your signals?

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2007\05\26@092234 by saddleman

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, saddleman@csufresno wrote:

for ton of information megasquirt.com has a really cool fuel injection kit. I am borrowing their info and adapting an sx-48 to control everything to build a fi system for an 1800 cc vw . as the project progresses i will post
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2007\05\26@100000 by bennettdann/a
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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, bennettdan wrote:

saddleman,
We brought up megasquirt in an earlier post, I plan to use the SX48 also to make my V6 in my truck run. I am sorting out the wiring and going to test some of the signals on my truck with an Oscope this weekend if the weather holds out..Mark has a nice bit of code you should look at and his is already running and I think he use the info on the megasqurit sight has a helping hand. He uses the SX 28 to make his run so the internal timer on the SX 48 should be that much better..

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2007\05\26@101852 by johncouturen/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, johncouture wrote:

William,
Great idea!  As I know nothing about fuel injection, I'll proceed as the group suggests.  
The free Eagle CAD program has a size restriction of 100 x 80mm so we'll have to fit it on that footprint; modularize it or convert to a multi board design.

I'm just having fun using the Eagle CAD program.  The more I use it the more I learn.  I actually had a board made by PCBCart using the program and they came out looking beautiful!  PCBCart not only creates the board but also lays down a colored (i.e. green, red, blue, yellow, etc) soldermask layer along with a silkscreen layer for less per board than PCB FAB Express or ExpressPCB (qty 5) so I'm sold on them.

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2007\05\26@105043 by markistuffn/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, markistuff wrote:

Well Great news, i solved the backfireing problem.  The first few times i had the engine running it was really really rich,  so i fowled up the O2 sensors and it would over compensate and make the mixutre really lean.  i ended up disableing it temperaraly and set the ratio manual.  i connected some POTs to the unused analoge inputs on the board and used that to set the ratio.  and also i had to calcualte out the VE.  i would run the engine steddy at a certain RPM and adjust another POT that would control the VE%, and graphed it all out and made an equation for rpm vs VE.  the engine is only supost to rev to 3600 rmp, but i take it to 4500.  .  today im going to program that into the code.  the VE would be diferent for every engine i belive.  but now i can rev it at any rpm steady and as long as i have the VE set right it runs perfect. no backfireing.  oh i checked the ignition and it was out a tiny bit.  another thing i forgot to compensate for is the time it takes for the injectors to open up, so i programed that in as well.  ill upload the newer version of the code once i get it finished and tested.

So for my setup i think the mosfet drivers im useing will be allright.  the engine is a industiral aircooled 842 cc engine.  but for any bigger aplication it would be a good idea to switch it to the IRL510's.  Im useing High Resistance Fuel Injectors so i dont have to run PWM,  i just used the pulse out command and it gives it full power for the entire pulse width.  but yes if i knew more before i started the project i would have gotten alot of differnt parts.  especialy the sx48,  but its a learning prosses.

William asked what the SR8 port is for.  well when i have time and have figured out all the programing exquations for the fuel injection. i plan on using that as a seiral input output to the computer so i can send and read what is going on inside the engine while its running.


I need to find a really fast and effective way to get the engine RPM.  i cant use the count option as it will take to long.  i was thinking  of using PULSEIN, and have it only time the amount of time that the Hall sensor is reading 0.  i think its for only like 20degrees of each revolution.  but if i can get that time then multiply it by the correct constent, the i will beable to get the rpm value.  thats the only way i could figure. unless i have the rpm somehow going into a anloge input and just read that. but im not sure how to do that.  ill give the pulsin a try but any sugestions would be apreciated.

Thanks everyone for your input into this project
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2007\05\26@112828 by Capt. Quirkn/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, Capt. Quirk wrote:

Your making your own ECU, your not bound to restrictions the OEM's use in their own units
Fuel ratios very from about 10 to 16:1 depending on the situation and the rpm.

I believe Mega Squirt has downloads for adjusting their maps. It's a usefull example.

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2007\05\26@113409 by bennettdann/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, bennettdan wrote:

I agree with you on that Capt. Quirk its that most motors with a 14.7 to 1 AFR tends to have the best fuel economy but most high power vehicles run around 12.5 to 1 its just depends on the motor and combo of parts on it..

The standard o2 sensor outputs a very small voltage change between 12 to 1 up to 15.1 so the tunning is not as accurate with a standard o2 sensor the standard one use .45vdc output when it is at 14.7 to 1 and the wideband o2 sensors put out 2.5vdc at 14.7 to 1 and have a much wider reading range this makes tuneing with them a more accurate situation..

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2007\05\26@213832 by Capt. Quirkn/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, Capt. Quirk wrote:

Best economy and leanest fuel mixture at peak torque.

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2007\05\27@233249 by Shawn Lowen/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, Shawn Lowe wrote:

Sorry-
I couldn't get megasquirt to pull up. Is it www.megasquirt.com?

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2007\05\28@055834 by williamn/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, william wrote:

Mark,
I think you need to use assembly language.
You haven't started talking to the PC yet but you are already facing timing problems with pulsein and pulseout.
If you use assembly, 20Mhz would be more than fast enough to do everything required.
I will help you with the assembly language if you need my help.

Another thing, I always use 1K resistors between the SX and the PC or notebooks and never had a problem.
I never needed the 8v supply for serial communications.
If you trust me on this, then the new board design need only one 5v regulator.

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2007\05\28@204458 by bennettdann/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, bennettdan wrote:

William,
    I have one question for you why are you so set on mark having to run this project on 20mhz? The megasqurit and alot of the OEM ECU units use 50mhz and if he make the fuel control run on the 50mhz clock speed now when he gets into controlling his timming or controlling a tranny or anything else as it progresses the code will not have to be modified.

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2007\05\28@230832 by johncouturen/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, johncouture wrote:

Bennettdan,
William had indicated that the board may be using too much current and if the mcu were lowered to 20mhz along with some other tweaks it would reduce the current consumption, eliminate the need for two regulators and lower the heat signature of the board.

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2007\05\29@095847 by bennettdann/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, bennettdan wrote:

John,
    I see what you are talking about but his is using the two regulators because one is for the 8v for his comm to his PC circuit but the 1 amp regulator he has should provide plenty of current. Someone suggested using a Max232 chip so he could use on 5v regulator so he wont have to piggyback the regulators.

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2007\05\29@135658 by johncouturen/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, johncouture wrote:

To all, the recommendations to date:

1) change MOSFET MIC4422 to IRL510 (IC4,5,6,7) to handle larger load and eliminate 8.5 voltage requirement
2) swap out A1015 for a Max232 to eliminate 12V requirement and allow communication with laptop via standard RS232
3) provide easy (and small) connector for RS232
4) use one 5V regulator
5) reduce MCU mHz if possible to reduce heat and power consumption
Mark,
What sensors are you using?  i.e. datasheets URL's on hall effect sensors?

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2007\05\29@140909 by bennettdann/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, bennettdan wrote:

John,
   Myself and Bean think that you would have a better PWM signal if you used the internal timer on the SX48 also...

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2007\05\29@164824 by Ibsenn/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, Ibsen wrote:

I think I read on the MegaSquirt site, that you need to monitor the battery voltage and compensate the injectors on time...
I think that the injector open and close slower if the voltage is low...

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2007\05\29@182631 by williamn/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, william wrote:

I went to megasuirt.com and saw the Megasquirt II ECU running at 24Mhz.
Why don't we decide on a 3 pin thru hole resonator, so we can use 20 or 50Mhz later depending on personal preferences.

Are the injectors common positive ( common anode )?
If it is, then the IRL510 is beautiful, b'cos it pulls the other injector pin to ground.
If they are floating, the IRL510 will also do.
If they are common ground, we need to change to a p-type mosfet.

BennettDan,
Even though the 7805 regulator can handle up to 1 amp, it needs plenty of heat sink.
To handle even 500mA, dropping 13v to 5v, it will heat at 4 watts !
From my experience, it can only handle up to 150mA without heat sink in tropical countries.

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2007\05\29@225232 by Capt. Quirkn/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, Capt. Quirk wrote:

I checked out their mpu chip specs, it runs at 40ns/cycle
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2007\05\30@001313 by williamn/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, william wrote:

40ns / cycle means about 25Mhz right?
How many cycles per instruction can be MPU execute?
If it executes at 4 cycles per instruction, the SX is already 4 times faster at the same frequency.

Bean,
Do you recommend SX/B be used for ECUs?
Tell us your opinion.

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2007\05\30@092309 by Ibsenn/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, Ibsen wrote:

How about using this 5V 1A Switching voltage regulator ?   (http://www.dimensionengineering.com/DE-SW050.htm)
It has it's own heat sink....


Model:              DE-SW050
Performance:        Up to 30V input range
                      83% typical efficiency, up to 87%
                      <2% ripple
                      1A output (continuous)
                      1.25A peak output (1 min)
                      1.3V typical dropout voltage at full load
                      Can be put in parallel
Applications:        Battery powered applications
                    Robots
                    Point of load voltage regulation
                    Any application where a linear or LDO regulator is dissipating too much heat or a large heatsink is undesirable
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2007\05\30@095522 by beann/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, bean wrote:

[Quoting: "william chan"]
40ns / cycle means about 25Mhz right?
How many cycles per instruction can be MPU execute?
If it executes at 4 cycles per instruction, the SX is already 4 times faster at the same frequency.

Bean,
Do you recommend SX/B be used for ECUs?
Tell us your opinion.

I'm not familiar with ECUs, but looking at the fuel1.sxb file it looks like the main program loop is I/O bound by the I2C commands reading the sensors.

I don't see any reason why SX/B wouldn't work. There are very few program that SX/B or SX/B with a bit of assembler won't accomplish.


Any project that requires PWM would greatly benefit from the SX48. Using an interrupt on the SX28 is a great waste of processing power (though it is useful to be able to do it).


Bean.

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2007\05\30@194910 by williamn/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, william wrote:

Bean,
I am also not very well versed with SX/B.
I need to ask you a question.

If a main loop of a SX/B program is busy with the I2C communications, how can we ensure that incoming serial
bytes from a PC won't be lost?

Thanks.

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2007\05\31@100754 by Tinkern/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, Tinker wrote:

Being involved in building some hotter motorcycles etc for a while I'll just toss in my 2 cents on A/F ratio's. First part being, that varies drastically by engine design, most of the bikes I deal with would melt holes in things anywhere close to 14.7:1 so thats something to keep in mind, most 2 strokes are considerably richer than that as well as most cars at any kind of load at all.

The 12.5:1 number that John threw out is a good full throttle starting point, and be very very careful taking any gasoline engine above about 13.5 at any condition other than idle. There are a tremendous amount of calculations and variables to deal with to attempt to run something at a stoic ratio. First being what was the original engine designed for?

The project is awsome Marki, keep it going.

My 2 cents on the clock speed thing?  If the chip is stable at 75 I'd go for it. For my own applications I've stopped at 50mhz strictly due to environmental concerns. Sealed enclosure, heat build up etc etc. Keeping in mind Marki's very realistic 14,000 RPM goal... The more clock the better I say, at 20 there's a very sneaky suspicion that its going to run out of power fast trying to do real time processing..

14,000 RPM is 233 rev per second, or 4.29ms per revolution, in end result on each revolution on a 2 cylinder, you need to fire the ignition, control dwell, timing advance, and fire the fuel injector as well as control injector duty cycle. Maybe everything doesnt have to be recalculated for every revolution but odds are the full sensor array will have to be read, stored, and values redone more often than most people think. Under full accel any delay in doing true real time calculations will result in a drift in the air fuel at minimum. So what is acceptable drift? How fast will it drift? What is the rate of accelleration?

Marki, huge props on this one. Its always been beyond my level of bravery and yours is already up and running!

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2007\05\31@104604 by beann/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, bean wrote:

[Quoting: "william chan"]
If a main loop of a SX/B program is busy with the I2C communications, how can we ensure that incoming serial
bytes from a PC won't be lost?
William,
 You cannot. Just like the BS2 the program must either wait at the serin command, or impose a timeout. Either way the code must be executing the SERIN command of the data will be missed. Unlike on the BS2 it's not too much trouble to use interrupt driven serial input using SX/B. I believe Jon Williams has posted several programs that do this.


Bean.

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2007\05\31@124057 by George Framen/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, George Frame wrote:

Hi,  I am an engineer and have been involved in Engine Performance Development at both Ford and Chrysler Corp for more years than I care to mention.  This work has keep me involved with many different type of engine controllers and strategys.  I think your project will be awsome, making a controller from the SX chip, great project.  Certianly, using a Speed-Density system approach will be the most stable.  
MFR air = Density * (Volume Flow Rate)* VE
MFR fuel= MFR air/(A/F)
Volume Flow Rate can be calculated from the engine displacement and the RPM.

So, the requred PW is determined from the fuel mass.

Remember, the MAP sensor requires a small orfice (~0.020" to 0.035") to damp out the dynamic pulsations that are present in any intake system, especially at higher loads and RPM's. Also VE (Volumetric Efficiency) can be estimated, for a first cut try 0.90.  The only other thing I would mention here is that to drive a ignition coil primary voltages can be very high ~ 500 V and we usually use a IGBT to handle this.

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2007\05\31@150535 by Ibsenn/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, Ibsen wrote:

Would it be feasible to use the Multi Threaded SX/B,  discussed in a previous thread ?

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2007\05\31@165821 by Sparks-R-Funn/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, Sparks-R-Fun wrote:

It is not terribly difficult to add a background UART to handle serial communication under SX/B.  While it is true that you can not use the built-in SERIN and SEROUT commands to do so it takes only a little more effort to learn to use subroutines written by Bean, JonnyMac or others.  In fact, the one I use the most is written entirely in SX/B.  It simply handles the bits directly instead of using the built in commands to do it!

- Sparks
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2007\05\31@165911 by bennettdann/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, bennettdan wrote:

GAF,
    I though the primary voltage on the ignition coil was still just 12vdc then is raised that is what the coil is for so you just switch the 12vdc with a PWM signal and the ignition coil will fire? Can you explain the 500v you are talking about in more detail?

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2007\05\31@174422 by George Framen/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, George Frame wrote:

Bennettdan,
Yes, you are correct in that we supply 12V DC to the primay side if the ignition coil.  When the magnetic field collaspes it induces a voltage into the primary somewhere between 200 and 500 V, depending on the type of ignition coil.  The purpose of the condenser on the old "points" system was to prevent arcing at the contacts as a result of this voltage.  Hope this helps

O2 sensors usually read between 0.7 to 0 volts:  or High when when it the A/F is Rich and Low when it is Lean of stoichiometric.  A comparator should work fine.

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2007\05\31@183030 by bennettdann/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, bennettdan wrote:

GAF,  
    Do they use some type of flyback circuit to route the power back into the battery or do they rely on the diode in the IGBT to handle the spikes?

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2007\05\31@222724 by markistuffn/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, markistuff wrote:

I have been busy the last few days working on other projects that have higher prioity, like reroofing, and building a fence, etc.   All the input and comments everyone has are great.  hope all this info that has all been bought together can helpout others oneday who want to tackle a simlare project.  

i took the buddie out for a little test drive up and down the block.   thier are a few things that i have to work out.  i found out that the VE is alot differnt when the engine is under load verses no load.   so i need to reprogram that.  and my throttle body really didnt work to well. tryed to build one but it lets it idle way to high, so i got a good throttle body and need to hook it up.  then thier are a few things i need to program into the code.  

GAF - im not sure if im doing the right equations to calculate out the pulse width.  when i was writing them up i noticed that the rpm was cancled out, so i just left it out.  hopefully that dosnt cause to many problems.


Air Density (kg/m) = 1000 * MAP(KPA) / 287 * TEMP(K)

Pulse Width (ms) = AirDensity(Kg/m[/4]) * Displacment(m[4])/2 * Ratio(fuel / air) * InjectorFlowRate(ms/Kg) * VE  + Injector Opening Time(1 ms) + Accelorator Enriching.

for the accelorator enriching.  i have the sx read the value of the tps and store it.  then next time round it reads the new tps value and tackes the differnece, only for opening, and mulitplys it by a constent to give me how many ms pulse width to add to make it have no hesitation.


I'll try restricting the opening to the MAP sensor see if that helps smooth things out.

I've been trying to write an equation to figure out the VE.  i wrote one but it applies to when the engine has no load on it.  when a load is attached it requiires alot more fuel.  before i had the VE porportate only to the RPM,  but when i get some time ill do some testing and figure one out to give me the VE in relation to the MAP reading and RPM.   the engin is very inefficent. its a old flat head horizontaly opposed kohler.  its only supost to run to 3600 but it runs safe up to 4000 rpm.  but the reason for such high MHz is i want this project to beable to be used on a motocycle engin eventualy that goes up to 14000 rpm.  the buggie is my testing grounds for projects.


i attached the last version i made of the program. its very messy and i havent done any of the fixes i mentioned earlyer.  probable wont get around to it for a few days.  going camping this weekend.  but the engine sure starts up great.  before i used to have to crank the engine for about 30 seconds with the choke on before it would fire up and stay running. now just bairly hit the starter and it fires right up.

 
BTW, i havent started school yet.  i plan on going to a tech school in september for electrical engineering.  i figured this project would get my "feet wet" in what i want to be doing.

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'[SX] Fuel Injection'
2007\06\01@023004 by williamn/a
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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, william wrote:

What is a MAP sensor?

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2007\06\01@034424 by George Framen/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, George Frame wrote:

Markistuff,
When you developed your equation for mass flow and the engine RPM cancelled out, then something went wrong.  Without engine speed your Speed-Density system degrades to just a Density system.

MFR air = Density * (Volume flow Rate) * VE
Density= MAP/(R*T)   where: MAP = manifold absolute pressure
                                           R=gas constant
                                           T = inet air temperature
Volume Flow Rate =Displacement * RPM
Therefore:

MFR air = (Disp * RPM * MAP)/(K *T) * VE    where: K=const to make the units work
MFR fuel = MFR air/(A/F)
for most fuels and MAP levels 75% of max MAP you can run stoichiometric ie. 14.6 lbm air/1 lbm fuel and stay closed loop with the O2 sensor.  Beyond that you shoud be in open loop and run richer 12.5:1 is fine.  I do not know what kind of engine you are using be generally a lean A/F at high speed and load will result in a piston with a large hole in it.

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2007\06\01@102030 by Ibsenn/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, Ibsen wrote:

If you are going to design another board using the SX48, why not update it to be able to run a 4 cyl, V6 or V8 engine.

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2007\06\01@125754 by George Framen/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, George Frame wrote:

Bennettdan,
For the ignition drivers they use a IGBT with an internal diode to handle the voltage spikes.  I was just looking in the Digi-Key catalog and they have some manufactured by International Rectifier in a TO220 case for around $3.50 each.

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2007\06\01@151417 by bennettdann/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, bennettdan wrote:

Gaf,
  I have a few IGBT around here that should work fine, I used them in some DC chopper drives a while back and have some left over.

In my truck I have a HEI distribitor and it has a modual that outputs a signal each time a piston reaches TDC and then recieves a dwell PWM signal to fire the Coil how so they figure the dwell do they take in the pulse then just average out the timming advance dwell compared to the RPM of the motor or is their other variables happening?

I would like to convert my truck over to coil per plug like the newer motors run and keep up with the timming with a better RPM sensor say maybe like a resolver with as many teeth as cylinders plus one extra Sync notch.

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2007\06\01@151957 by bennettdann/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, bennettdan wrote:

Ibsen,
   Unless you are using sequencial fuel injection where each cylinder is firing the it own injector at a certain time it does not matter how many cylinders the motor has it because most EFI systems fire in a Batch of all the injectors or bank to bank where they fire from left bank to right bank. So you can take the same controller to run a 2 cylinder or a 12 cylinder it only needs the right injectors and VE table (tune) setup.

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2007\06\01@152911 by Ibsenn/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, Ibsen wrote:

bennettdan,
You are right, I was thinking about Ignition control...
If we used Waisted Spark Ignition control we only need half the number of I/O's to # of cylinders ( I think I got that right)...

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2007\06\01@161750 by bennettdann/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, bennettdan wrote:

Ibsen,
   I see you are talking about the mutispark control of an MSD ignition, I dont think to many OEMs use it. I dont think I need it in my truck I have ran the MSD boxes and the HP gained is not to much a little better fuel economy but very little.

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2007\06\01@180910 by johncouturen/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, johncouture wrote:

(grin) Ok, I can draw up another board but I'm lost!  How would I do multiple cylinders?  What connections would be made where?

William, I use three pin resonators where the center pin is ground.  Is that the type of resonators you mean (i.e. "Ceramic Resonator CERALOCK")?

See page 11 of this datasheet:

http://eweb.chemeng.ed.ac.uk/jack/radio/projects/p16e9.pdf
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2007\06\01@184850 by George Framen/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, George Frame wrote:

bennettdan,
Those IGBT's should work fine to drive to ignition coil.


For you truck motor, not sure of the model and year but it still may have a centrifugal advance located below the breaker plate. This would handle the spark advance with RPM but not with throttle position.  In the past that was handeled with a venturi vacuum applied to a diaphram attached to the breaker plate.


For injection timing, all manufactures today use sequencial injection timing.  Even though this is common, when to inject the fuel varies alot.  At Ford we calculated when the end of injection would occur the started the injection so that it would finish before the intake valve opened.  This provided the longest resident time for most of the fuel to vaporize.  At WOT and higher engine speeds this is not possible since injectors are just about full on (90%).  That is if the injector is sized properly for the engine.  Small enough so that idle pulse width is gearter 1ms and peak pulse width approaches approx 90% injector on time.

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2007\06\01@195213 by bennettdann/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, bennettdan wrote:

John,
   All you need to do for the extra Injectors is use an Optoisolator connected to the SX pin you have the Injector mosfet on and then out of the Optoisolator to 4,6 or 8 mosfets for a batch injection or use two Optoisolators one on each of two SX pins so you can have bank to bank injection or use an an OptoIsolator for each Injector mosfet per cylinder not many people will need more than 8 cylinders but others could be added and then we can create a daughter card if the need be. But we need the optos to protect the SX from spikes and the mosfets need reverse diodes also.

GAF,
   The new cars that have sequencial use it to make better fuel economy not so much for HP right? I have been seeing alot of high HP motors latly that use say 16 injectors on an 8 cylinder so that it will provide the Idle quality with the smaller ones running sequencial and when the boost kicks in they run both sets at bank to bank then batch for full out racing.

Guys,
  Remember their are so many options when making your own system so why dont we settle on a PCB layout that has the ability to run all options that we can think of then only code in what you need for your application and we might get a group buy on the PCB boards.

On my truck I want to be able to add a turbo some day so I would like to be able to run extra injectors so we need a connector to run a addon daughter board, also sense a wideband O2 may be used it needs a A/D converter instead of just a comparator circuit. I would also like for it to control a TCU transmission controller for different makes of auto so another connector is needed for it.

So how about we make suggestions and I add it to this Post and then when we all agree we see how much we can have them made for?

We have 48 pins to play with here.
1) Ability to run 8 sequencial injectors and then two extra outputs of ban to bank add on injectors. 48 - 10 = 38 pins left
2) MAP (manifold absolute sensor) 38-1=37 pins left
3) O2 sensor 37-1= 36 pins left
4) IAT (Idle air temp sensor) 36-1=35
5) Fuel Pump Relay out 35-1=34
6) RPM input 34-1=33
7) IAC ( Idle air control motor/valve) 33-1=32
8) CTS ( coolant temp sensor) 32-1=31
9) Ignition outputs from single coil to muti coil 8 outputs 31-8=23
10)TPS (throttle position sensor) 23-1=22
11)
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2007\06\01@203320 by Ibsenn/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, Ibsen wrote:

It would be good to have a second MAF for reference.
That will allow the system to compensate for altitude.

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2007\06\01@203820 by Ibsenn/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, Ibsen wrote:

bennettdan,
I like the MSD due to the distributor less setup !!!
I'm all about less mechanical and moving parts...

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2007\06\01@204216 by bennettdann/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, bennettdan wrote:

Ibsen,
   You could have the sensor correct for that each time the vehicle starts up. The Map should read what the pressure is outside just before startup.
Or do you want it correct as you are drive? I dont know if you would need it unless you traveled alot of long trips.

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2007\06\02@002012 by Ibsenn/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, Ibsen wrote:

I vote for a second MAP, which is not a problem with a multichannel A/D.

You need to use a serial multichannel A/D converter, the SX48 does not have an internal A/D converter...

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2007\06\02@014608 by williamn/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, william wrote:

GAF,
IGBTs or Mosfets are better to drive the injectors?

bennetdan,
Why do we need PWM Output for the injectors?
Wouldn't a simple high or low output will do?
What is this TCU thing about?  Seems like wasting a lot of pins.

16.) Serial Port to PC or Notebook ( 2 pins)
17.) Serial Port to Propeller chip to display RPM and such on a small LCD TV.  (2 pins)
:cool:

John,
The Murata 20Mhz and 50Mhz thru hole ceramic resonator that Parallax sells will do just fine.
Don't forget a 1M ohm parallel resistor across OSC1 and OSC2 for stability.

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2007\06\02@071711 by bennettdann/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, bennettdan wrote:

William,
   Most all of the Fuel injection controllers vary the duty cycle to the injectors so PWM should be the best. The TCU is a Transmission controller for electronic trannys.

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2007\06\02@090907 by johncouturen/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, johncouture wrote:

To all,
Just a quick note.  As noted above, it might be useful to incorporate an SX48 into the design.  The SX48 proto board ($10) is just about 80mm x 100mm, so it might be handy for our next design to be a daughter board of the SX48 protoboard.  That eliminates the need to solder the tiny leads of the SX48 and it provides a power source along with a programming port.  Sounds like a nice neat stack to me!

SX48 board can supply up to 1 amp at 5VDC.

(FYI, 80 x 100mm is one of our board size limitations because that it the max that the free version of Eagle CAD will allow)
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2007\06\02@193312 by Capt. Quirkn/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, Capt. Quirk wrote:

Skip the RPM and use a:

#18 CPS, Crankshaft position sensor
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2007\06\02@204735 by bennettdann/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, bennettdan wrote:

John,
    I can draw one up in expressPCB their boards can be alot bigger but it has to be made by them.

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2007\06\03@005917 by Capt. Quirkn/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, Capt. Quirk wrote:

GAF,
I have been concerned with the resources that are used by the COUNT command for gathering RPM data. On my simplest system I eliminated RPM from the program all together and I just use a very small map (6 TPS points) and correction by a CHT for an 80cc 2 stroke single. I have a brake style dyno for small engines up to 30 HP, but I haven't need to use it.

Do the Automotive manufactures calculate rpm by measuring the angular acceleration, between two points?, on a CPS or gear tooth sensor
Bill
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2007\06\03@093141 by Ibsenn/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, Ibsen wrote:

New systems use a gear tooth sensor...

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2007\06\03@095026 by johncouturen/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, johncouture wrote:

BennetDan,
That's a possibility.  Let's see where this project leads us and use that as a backup plan.

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2007\06\03@132324 by George Framen/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, George Frame wrote:

Capt. Quirk,
Most manfactures use a 60 tooth spur gear in conjunction with a mag pickup attached to the dyno.  The the output of the mag pickup is converted into a square wave and they just count the pulses for a fixed period of time.

On the engine there is a 40 tooth gear keyed to the crank and a single pulse generated at the camshaft.  The combination of these two signals provide all the information that is necessay to calculate engine speed, injection timing, and ignition timing.

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2007\06\03@173026 by williamn/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, william wrote:

GAF,
Is there such thing as a partially opened injector?
Can an injector be opened only partially or it must be opened fully at any time.
If there is no partial opening of injectors, then we don't need PWM for injectors.
Just a simple on or off will do.

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2007\06\03@193008 by Capt. Quirkn/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, Capt. Quirk wrote:

I have mostly used CHT's with the 14mm ring to fit under a spark plug or glow plug adapter. I would rather use a thermocouple that is screwed into the head, but often, castings are thin or it just isn't easy to do. Has anybody seen a 14mm CHT that doesn't break easily or is it a problem best solved with braided thermocople wires instead of solid?

Also EGT's usally need to be within 3.5 to 7" from the piston or a valve. Is there a critical length for an O2 sensor?

Bill
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2007\06\04@043601 by George Framen/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, George Frame wrote:

William Chan

There is no such thing as a partially open injector, they are either on or off.



Capt. Quirk

I made a mistake on the number of teeth on the crank pickup.  The wheel that is keyed to the crank has 36 minus 1 teeth.  The reason for the minus 1, is there is a missing tooth, that allow the processor to determine crank position.  In addition the cam sensor would allow it figure out cycle position.


Yes, I have been involved in a number of SAE papers, and also was on a SAE committe to rewrite SAE J1349 (engine prerformance rating).  I retired from Ford about a year ago.

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2007\06\04@094020 by Capt. Quirkn/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, Capt. Quirk wrote:

WOW!

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2007\06\04@094213 by Capt. Quirkn/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, Capt. Quirk wrote:

WOW !
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2007\06\04@230236 by Capt. Quirkn/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, Capt. Quirk wrote:

GAF, 36 t gear, nice even nunber.

Is there a significant advantage to a sequental EFI system, where all cylinders are monitored and controled as individual cylinders to maintain a power balance between all cylinders ?


Works nice on a 2 stroke twin, but I would only call it an advantage over similar race engines.

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2007\06\05@014827 by williamn/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, william wrote:

Sorry GAF,
A few more questions if you don't mind.

1. Are the Injectors usually common ground, common positive or floating?
2. Can we open 2 or more injectors together at the same time using one MOSFET?
3. In your opinion, IGBT or MOSFETs are more suitable for driving injectors?

Thanks.

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2007\06\05@035300 by George Framen/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, George Frame wrote:

William Chan

Injectors:


1. The injectors are held at 12VDC then pulled to ground, through the driver, to turn them on.


2. You should use a single driver for each injector

3. You could use either an IGBT or a MOSFET as a injector driver, just make certain it has a high enough rating to handle the load.  Aleast a couple hundred volts with a internal diode for the fly-back voltage and about 10 amp rating.



Capt. Quirk

Manfactures use sequential injection for the best cylinder to cylinder balance and to keep feedgas emissions to a minimum (better fuel prep and good cylinder-to-cylinder distribution).  

After all these years of working on engines I do prefer Fuel Injection, because it works so damn good.  I think you would need to work on a A/F distribution problem with a carb system for about 6 months to appreciate how good an EFI system really is.

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2007\06\05@080834 by bennettdann/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, bennettdan wrote:

GAF,
   What do you know about timming circuits, do they use the 36 tooth and geartooth sensor to calculate the timming or do they use the cam sensor?

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2007\06\05@192232 by williamn/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, william wrote:

John,
Your idea of using the SX48 protoboard is fantastic.
Looks like we can use the IRL510 mosfets to drive the injectors since the injectors are common positive.
Don't forget the free-wheeling diodes.
Do you want 6 mosfets to cater for V6 engines or 4 mosfets to cater only for 4 cylinders?
I would think we start with 4 cylinders first, I wouldn't want to get too ambitious with a Version 1.0 board.

How long did you take to learn eagle?

Thanks.

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2007\06\06@040802 by George Framen/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, George Frame wrote:

Bennettdan,
Signal Timing:

They use BOTH the 36 tooth gear and the pulse from the cam to determine where they are in the engine cycle.  
Injector Pluse:

Not sure what you are refering to, but they do NOT send out a frequency signal to open the injector.  As I explained in my last reply, one side of the injector is held at Vbat and then the other side is brought to ground, through the driver, to open the injector.  This is a single pulse, not a frequency.

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2007\06\06@045803 by williamn/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, william wrote:

GAF,
When you mentioned "higher engine speeds this is not possible since injectors are just about full on (90%). ",
does it actually mean that the injectors are spraying fuel into the cylinders even during the exhaust stroke?

When you mentioned that "running an engine lean at high speeds will create a hole in the piston", does it mean that the piston rings will wear off or literally a big hole will form in the middle of the piston?

Thanks.

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2007\06\06@100621 by Tinkern/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, Tinker wrote:

A lean condition creates excessive heat, lean at high speeds more so. Literally a large hole in the center of the piston. PWM for the injectors would be something you would want as a current limit on low impedance injectors, or peak and hold where the injector is opened with a current spike and holds open on lower current.

Direct driving low impedance injectors creates excessive heat. Look at fuel injectors as a current controled device instead of voltage......

Also, yes they can be open on the exhaust stroke but the intake valve is closed so they are sparying fuel into the intake tract, look at it as "precharging" the intake tract so that the fuel is ready when the valve opens and the piston sucks the fuel and air in....

Many happy ventilated pistons...

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2007\06\06@104717 by George Framen/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, George Frame wrote:

William Chan,

When a injector is properly sized to an engine (for conventional automotive applications) there is not much room left at the top end to get all the fuel in during the intake stroke.  There will be some fuel left behind in the intake port but not much of it is pulled over to the exhaust side during valve overlap since the exhaust pressure is much higher than the intake pressure (at high engine speeds and WOT conditions).  

When I mentioned lean conditions can result in a failed piston I was refering to the fact that cylinder temperatures can get very hot under lean conditions.  And these are usually high speed and WOT conditions.  What usually happens is the spark plug starts to melt and becomes a source for preignition. This causes an over-advance-condition on the engine and pistions get very hot.  Normally piston crown temps are in the range of 500 F and when the engine gets into preignition these localized temps can exceed 1300F. Thus a hole will form in the center of the piston, directly below the spark plug.

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2007\06\06@105751 by williamn/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, william wrote:

ChrisP,
Thank you for your kind input.
I would think that the piston alloy is made withstand high temperatures, so literally creating a hole in the middle is unheard of in my country.
If the AF ratio is intentionally made rich as a "coolant" to cool the piston, wouldn't it be killing fuel efficiency?

I still think that we don't need PWM to drive the injectors, b'cos the on time is only a matter of a few milliseconds.

I think modern engines directly inject fuel into the cylinder, not into an intake tract, unless it is a "indirect injection diesel engine" like in a 2000 Ford Ranger.

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2007\06\06@121459 by johncouturen/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, johncouture wrote:

William,
Time to learn how to use Eagle:  1 complete board (grin). In other words, I went from concept to a finished PCB and by being determined to figure it out, I learned the product.  They have a great support forum also which is free just like the program.  I never did figure out how to do a rectangular hole for the 2.5mm power jack that I used on my PCB.  I just have to get on the forum and ask.

In time, I think I worked on a schematic for about 6-8 hours one day and I was pretty dangerous with the program.  Probably another 4-6 hours learning how to draw new parts, layout the PCB and how to draw "restricted" zones and ground "pours".  From there is was a matter of tweaking my design and learning new techniques.

Most parts I physically had in my hand so I measured them with a digital caliper then drew them and added them to my "library".

The board turned out much better than my expectations and needed only a few wire "fixes".  One trace was too close to a mounting hole, the holes for the diodes were specified as being  too small, etc.  All of the errors were mine, not the PCB manufacturer (PCBCart).

I think the best thing about learning it is that it will work with ANY PCB fabricator.  Thus, I can now pick and choose the fabrication house that I want.  
Finally, I would equate the learning curve to something like Adobe Photoshop.  Some of the commands in Photoshop are not exactly intuitive.  Same with Eagle.  However, those that have learned Photoshop would not go back to any other program because of its versitility.  I guess I feel the same about Eagle.

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2007\06\06@121849 by johncouturen/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, johncouture wrote:

Oops, forgot to post a picture of it.

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2007\06\06@142041 by bennettdann/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, bennettdan wrote:

William,
   Just about any motor could be leaned out enought at WOT to pop a hole into the piston no matter how good of a alloy its made out of.
Also if you dont plan to use PWM and you plan to use just a pulse how are you planning to time the pulse?

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2007\06\06@174916 by williamn/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, william wrote:

BennetDan,
To time the pulse, I think we could start with longer pulse to aid starting, ( making the AF rich ), then slowly within the next few seconds reduce the pulse width until the O2 sensor detects some oxygen.  This is just my idea, it could be wrong.

John,
I am also starting to learn Eagle, ( I was using ExpressPCB ), but when I printed the Schematics, the texts came out as black blocks.
The silkscreen text on the PCB also printed out as black blocks.  What is the problem?
On the screen it looks ok.

Thanks.

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2007\06\06@194028 by bennettdann/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, bennettdan wrote:

William,
   Their are two types of injectors that I know of their is the High impedance (12-16 ohms) and Low impedance (1.2- 2.4 ohms). most of your typical port injectors I.E. one injector per cylinder are Low Z (impedance) injectors and they use PWM to control the current to them so they do not get hot. The High Z injectors can handle the full load and use just a pulse width to control it. But you can add a series resistor to the Low Z injector to limit the current and then treat it like a High Z and use just pulse width then.

Here is the formula for the series resistor.
resistor ohms = (alternator voltage / 2.0 amps) - injector resistance
For example:

resistor ohms = (14.0 volts / 2.0 amps) - 1.2 ohms
=> resistor ohms = 7.0 - 1.2 = 5.8 ohms
and use atleast a 20 to 25 watt resistor.

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2007\06\07@061854 by williamn/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, william wrote:

Dan,
I think ECU design is a bit science mixed with a bit of art.
It could this art portion that creates myths surrounding ECU design.
We need to keep a clear and logical mind to separate myths from facts.
GAF has stated quite clearly that injectors only go on or off, no in betweens. I tend to agree.
Why would any injector manufacturer want to design a injector that can work with 2V when they know that
every electrical device in a car runs on 12V? Beats me.

He also mentioned that at high RPMs, the injectors are on about 90% of the time.
On this point, I want dispute.
As far as I know, injection only starts at the end of the intake stroke and has to stop before the power stroke.
That means, at the most it should be injecting fuel only 25% of the time.
At normal cruising RPMs, I would expect the injectors to be on less than 5% of the time.
So considering that 95% of the time, the injectors are in off state, over heating of injectors would not happen at all.

GAF has also recommended MOSFETS that can handle at least 200V.
I tend to disagree with this recommendation.
Assuming the injectors has a inductive coil inside it, yes it will induce a high voltage when it is switched off.
But by having a free wheeling diode across each injector, the voltage build up should not exceed 24volts.
Based on this explanation and my experience, I would continue to recommend the IRL510 as the injector drivers.

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2007\06\07@073426 by Chetn/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, Chet wrote:

Port and TB injectors can be open beforethe intake valve opens, which can be in excess of a 180 deg crank rotation.  For TBI the injectors can be open for 90% of the time, since they feed multiple cylinders.

Regards

Chet
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2007\06\07@093609 by Capt. Quirkn/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, Capt. Quirk wrote:

It's kind of like Direct Injection on 2 stroke engines. Up to a certain rpm the injector can fire while the exhaust port is closed. But at wide open throttle the injector is firing at BDC, while the exhaust port is all the way open. That's why an expansion chamber still works on a DI 2 stroke
GAF,
Are there injectors that require more then 12 v?,  significantly higher like 200v? , or
Can I drive a 12v injector, using 5v, to power an Inductor that produces 12v for the injectors and 300 v for an ignition coil?

Also, have you written any papers that are pertinent to this discussion?

SAE's online search engine isn't so great. If so do you remember their #, If not I'm going to take a drive to Cal Poly Pomona and look all your material.

Bill
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2007\06\07@094623 by bennettdann/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, bennettdan wrote:

William,
  Low Z injectors are called "Peak and Hold" the injector is switched on high for the first portion of the signal to overcome the internal spring then it switches into PWM mode to keep the injectors from obtaining to much current. See my attachment to understand what I am saying more.
High Z on the other hand you can just turn them on and keep them on and they will not get to much current.


But like I said you can use series resistors to limit the current the treat Low Z injectors like High Z.

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2007\06\07@101607 by Tinkern/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, Tinker wrote:

William,
 I dont think its so much art as someone having a very clear undestanding of everything that goes on in an internal combustion engine, as well as the capabilities of the electronics. To my understanding the idea behind a peak and hold injector is to allow you to use excessive amounts of current to produce a very fast opening time. The closer an injector pulsewidth is to a squarewave the more consistant and predictable, OR it could just be fuel pressure related.


Anyway, ECU design requires a very high level of skill in several disciplines, or a very well coordinated team of those disciplines.


Almost all gasoline engines in the U.S. are indirect injection, I'm sure there are some exotic DI's but dont know of them. Trust GAF, everything he's said has been spot on.


GAF Thanks, its been enlightneing.

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2007\06\07@104156 by johncouturen/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, johncouture wrote:

William,
RE: Eagle Text too Small
I think you set the text too small.  Remember you can set the text to as small as .01 so even an ant would need glasses!  I set mine at about 0.07.

Another thing to consider is the size of the schematic.  If you put a lot of stuff on it, Eagle will size it to fit on the page and thus shrink everything.

Download my schematic and look at the font sizes and print it out.  That way you can at least verify that Eagle can print a schematic and board layout.

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2007\06\07@105143 by Capt. Quirkn/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, Capt. Quirk wrote:

Let me clarify, I want to use an Inductor that produces 12 volts or more to drive 1 or 2 injectors. The inductor would have a 5v battery powering it. That same inductor board would also produce 300v primary voltage for a multi spark ignition system
What it comes down to, what is the amperage reqirments of a Low z and High z injector.

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2007\06\07@115811 by bennettdann/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, bennettdan wrote:

Capt. Quirk,
   The low Z injectors only need about 2 amps to operate. High Z you dont have to current control them but they are probaly to big for what you want.

The smallest injector I know of it a 9lbs/hr injector, do you plan to run the plane with a bosch style injector? I dont know if you could get a low enough amount of fuel out of it and not flood the engine.

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2007\06\07@131618 by Capt. Quirkn/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, Capt. Quirk wrote:

Thats ok, Big engines 80cc to 300cc with lots of NitroMethane!!  Need more Fuel.

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2007\06\07@133628 by bennettdann/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, bennettdan wrote:

If that is the case you might would start with two 44lbs/Hr injectors their are a few ford vehicles that use that size for their stcok injectors, you might be able to find a few in a junk yard to play with.

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2007\06\07@174622 by George Framen/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, George Frame wrote:

Hi Guys,
Just reading over the notes where we a talking injector flow rates etc.  How much thought is given to the fuel pump and the required fuel pressure to get these flow rates.  Most injector flow rates are specified at a nominal pressure usually 40 psi but I gave seen some higher. I know this is not a problem for the guys working on existing vehicles, but trying to adapt an EFI system to a small engine presents serious design problems, though not impossible.

Capt. Quirk,
For Nitro Methane the stoichiometric A/F is:  1.7 lb air / 1 lb fuel.  It is interesting to note that Nirto Methane has only about 1/4 the heating value of gasoline. The high power levels achieved with this fuel are a result the large mass of the fuel that is required for combustion, almost hydro lock.

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2007\06\07@222010 by Capt. Quirkn/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, Capt. Quirk wrote:

Fortunately we only use 25 to 30 % (about 4:1), But me and Mr. Hydro Loc met last summer, while running our 160cc twin opposed Unlimited engine. That cylinder popped off so Fast & 1 second later the whole engine was trash.

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2007\06\07@223341 by Capt. Quirkn/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, Capt. Quirk wrote:

My mechatronic :), system works fine right now without an injector.

For my system with an injector,I am trying to do it without adding a gear pump to the crank. The airplanes run 4 psi max fuel pressure, so either I need to modified a TBI or make my own. That was part of todays diddling.


But in the near future I'll be building a system for a 2180cc VW (HairDryer, lmao) and then for a modified Olds 215ci aluminum block V8 w/ Land Rover heads and injectors.

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2007\06\08@081356 by williamn/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, william wrote:

Dan,
I guess you have a point on the PWM thing.
Anyway, we can go ahead with the board design since PWM or no PWM, the driving circuit is the same.

GAF,
What is your opinion on Isuzu's DMAX 2.5 Direct Injection diesel engine which seems to blow all competition away, even the CDI engines.
They claim 1,400+ km on their 4x2 truck with just one tank of 76 litres of diesel.
Does this mean that Indirect Injection is grossly inefficient?

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2007\06\08@095549 by Capt. Quirkn/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, Capt. Quirk wrote:

I had a DI Ford F250 Powerstroke, It was a Hot ROD. and got 14 to 21 mpg.

I liked it a lot better than my Dads Dodge with a Cummins engine.

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2007\06\08@110131 by bennettdann/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, bennettdan wrote:

William if you use the resistors I have talked with a few people that have and it adds about 1 millisecond to the injector opening time and sense most take one second then allo for that in your code.

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2007\06\08@210100 by markistuffn/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, markistuff wrote:

I did find some time and put on the new throttle body and did some reprograming.  tryed to develop a 3d equation from info i gathered for my VE table.  and i also put all the wires in a nice harnes.  took it out today for a little ride on some trailes.  gotta say worked way way way better then the old carb that i had on it!.  but it still needs some fine tunning of the code to make it perfect.  i tryed using the serout command so i could see what is going on inside the ecu as its running.  i programed a little monitoring program in PERL, of all langueges, to read the serial port and desifer the infromation and then show it on the screen.  for some resone i could only run the sx serout command at a maximum but rate of 38400 witch is kindof slow. but any faster then i would get data corruption.  probably bad cables im using,  two 6 foot serial cables.  i had to make the sx only send one byte every engine revoution.  if i were to make it send too much then it would take to long and then the sx wouldnt be ready to read the hall effect sensor.

havent made use of the little eeprom that is on the board yet.  not sure how i want to go around makeing use of it.  maby eventualy use it to store the variables so they can be changed with out haveing to pull the crystal and used the sx-key.  i think that ill just used the equation to get my VE, i think it would be faster then sending a comand to the eeprom then haveing it send back the info.

The IC's im useing to drive the injectors work fine for my application,  did not lean out at high rpm and they just got a little warm while i was driving.  i have a waterproof plastic box that the pcb board is designed to fit perfectly in.  i think what i can do to keep it cool is do what they sometimes do with prossesors and heatpipes.  i could just have 2 heat sinks on for the inside of the box and the other for the out side. and have them connect to each other with some copper and make sure that i seal the hole in the plastic.  but right now everything runs fine with no heat sinks at all.  but once its inclosed im sure it will start to warm up.

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2007\06\08@210814 by markistuffn/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, markistuff wrote:

GAF, quick question
in the automotive industry, when building an engine and desigeing the fuel injection system for it,  what is the basic proccess of getting the programing code tuned really good?  do they used a dyno and get the proper variables (A/F, VE, ADVANCE) from trial and error? or is there a easer way to do it?
Thanks
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2007\06\08@232756 by Capt. Quirkn/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, Capt. Quirk wrote:

Markistuff, exactly what engine are you using in your buggy
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2007\06\09@002207 by markistuffn/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, markistuff wrote:

the engine im running is called K532  its made by kohler.   its 842 cc horizontal twin air cooled.  i got it from my uncle, it was on a machine for pulling 100's of feet of sprinkler pipe throught the ground, it had been siting for years and was all rusted up. the cyclenders were seized solid. i rebuilt the whole thing and the carb originaly wasnt good, and after it being so old it was really crappy.  hence came the idea of fuel injection for it.  plus with fuel injection i can easly run boost on it.  the engine is faily low compression and its a flat head.  so i think i would get more power by haveing boost rather then upping the compression.   maby if i get the urge i could add water injection on it as well to help cool the engine while its under load.... but thats another project for another time.

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2007\06\09@041110 by George Framen/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, George Frame wrote:

Markistuff,
To get the proper data to program the EEC many hours are spent on the dyno going through a process call Engine Mapping.  This is where at each speed load condition all possible parameters are swept though there full range, eg. spark is swept from full retard to full advance.  One of the main parameters measured during this process is fuel flow, so we can plot fuel flow vs spark advance, this determines the optimum spark setting for each speed load condition (the A/F is held constant at Stoich for part throttle and around 12:1 for WOT or is EGT limited).  The Mapping process takes about a month, 2 shifts a day 6 days a week.  I am over simplifing this process but I think you get the idea.

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2007\06\09@171604 by George Framen/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, George Frame wrote:

Markistuff,
The more I think about it there is a way to tell an engine to self calibrate itself and forget about this Mapping process that I just mentioned.  We already close loop on fuel control at part throttle (O2 sensor).  There are wide range O2 sensors that will read Rich or Lean A/F ratios, so all we would have to do is tell EEC what A/F we want to operate at then through feed-back it could set it.

The optimum spark advance occurs when the peak cylinder pressure is approx 14 ATDC.  If we closed loop on a cylinder pressure by means of a pressure sensor then spark timing would always be optimized.    
The problem with both of these concepts is they are expensive; wide range O2 sensors from Horiba around $1000 and cylinder pressure sensors from Kistler in the same range.

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2007\06\10@113143 by Capt. Quirkn/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, Capt. Quirk wrote:

GAF, For some reason I thought max HP was developed at 5 degrees ATDC, Is that correct?? Is there a range between optimal and max hp? Couldn't we use a ADXL150? or a knock sensor to determine peak pressure.

Also, have you ever used the 4 stroke model by Gordon Blair, if so is it worth the price tag. I own his 2 stroke model software. In profesional watercraft racing, knowing how to exploit some of his 2 stroke information, was the difference of finishing in the top 3 vs the top 10.

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2007\06\10@210813 by bennettdann/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, bennettdan wrote:

GAF and Markistuff,
 Their is a company that sells wideband O2 sensors with interface that outputs a Analog voltage from 0-5v and is not to expensive.
http://www.innovatemotorsports.com/products/lc1.php they cost $199 and are highly recomended buy alot of the guys I know that tune cars.

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2007\06\11@124607 by George Framen/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, George Frame wrote:

Capt. Quirk,
I have heard this a number of times, that max power occurs when the peak pressure is at 5 ATDC.   I believe this idea originally came from an engine text book by EF Obert, excellent book but he is wrong on that one item.  Over the years I have tested many different types of engines, from fast burn concepts to low compression to high output race engines. Each of these engines were equiped with flush mounted cylinder pressure sensors and a optical encoder, with 0.5 degree resolution, mounted on the front of the crank.  Virtually all of these produced the same result; that max torque or max power is achieved when spark is adjusted such that, the location of peak cylinder pressure is at approx 14 ATDC.  There is a small range of peak location over the entire engine speed range. At 1000 RPM it will be at 14 and decrease to about 12 at peak power (6000 RPM).  This concept holds true at part throttle also.    
Bennettdan,

I looked at that WEB site and I think that sensor is made by Bosch.  I have seen them used at work, Bosch calls them "Lamdba sensors".  They might be used in production somewhere in Europe which would bring the cost down.  The ones I used were made by NTK and were just for development, thats why they cost $1000.

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2007\06\11@150721 by bennettdann/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, bennettdan wrote:

Yes you can buy the Bosch sensors for around 60 dollars but you have to have the proper circuit to read it, its a little more involved than just a narrow band that you can read with a A/D converter.

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2007\06\11@180133 by George Framen/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, George Frame wrote:

Bennettdan,
Do you know where I could buy the Bosch Wide Range Sensor and the driver board?

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2007\06\11@192532 by bennettdann/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, bennettdan wrote:

GAF,
  You can buy the LC-1 from this sight
http://www.innovatemotorsports.com/products/lc1.php
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2007\06\12@181915 by RinksCustomsn/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, RinksCustoms wrote:

Okay i know most of yall r a bit sensitive to critizism, but i'll try to be constructive... and i would like to formerly welcome you all to my thread i'll be starting on my version of a DFI in the Propeller forum.

Awesome effort here guys!! Good points made in this thread and there were some helpful formula's over on the BS2 linked thread. Both SX and BS2 ECU's would benefit greatly from a "wide-band" O2 sensor however, allowing precision readings that are alot more linear than the "cheapy" O2 versions. Think i'm full of BS? Look up the datasheets for a standard "cheapy" O2 sensor and look at the linearity curve for voltage vs temp, it's a joke for reading stoich smoothly! The curve is so steep it's more like a high-speed comparator than an accurate thermocoupling device, yeah T/C, it doesn't sense Oxygen levels at all in case you were wondering. It's just a calibrated "high speed" thermocouple, and the cheap ones are a poor one at that.

A Wide-band version may cost more but the temp/volt curve is ALOT more linear giving you alot more presision that leads to a smoother running, better responding engine. I have a Buick Grand National on the stock ECU/block reading a wideband O2 provided through a bit of electronic conditioning and it runs very smooth, even if you "smack" it to the floor, currently the car is in the low 11's runing an 11.1 @ 121MPH w/a 60ft time of 1.5 sec, that's ~avg 550HP, i say average cause i was on/off the gas all the way down the 1/4, it's never been dyno'd, only calculated. I know now after looking at the numbers that the turbine housing was a bit small "choking" the engine causing it to break-up and mis-fire.

75MHz is not overkill for EFI, in fact, it's what most aftermarket DFI's are running close to, some are running @ 120MHz core speed "xFAST FI" or DFI i think it's called, it was at SEMA last yr - (Digital Sequential Fuel Injection).

Please view my thread in the propeller forum on this project, or subscribe to it if you like. But i'm almost expecting some critisism on my efforts, I'm hoping all your suggestions will inevitably lead to improvements as a set of fresh eyes will always have a different point of view.

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2007\06\13@093945 by Ibsenn/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, Ibsen wrote:

RinksCustoms,
I don't see you thread ?

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2007\06\14@193632 by markistuffn/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, markistuff wrote:

bennettdan - my older bro ordered a wide band o2 sensor, and he figured i could build a controller for him with the sx that would tell him what air fuel ratio he is running.  he wants it for tunning the carb on his cobra.  i orignaly thought the wide band worked of of off of 0 - 5 volt range for telling you the AFR but apparently it uses current one way or another to equate to the amount of air in the exsaust.  you wouldnt have any idea how to go about building a controller board would you?  or should i just tell him to buy one.  yes, ill use it as well for tunnin my fuel injection.  trial and error is a pain in the butt and takes along time.

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2007\06\14@195741 by bennettdann/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, bennettdan wrote:

Do you have a datasheet on the Wide band O2 sensor?

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2007\06\14@200343 by bennettdann/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, bennettdan wrote:

Do you have a datasheet on the Wide band O2 sensor?

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2007\06\15@090309 by Capt. Quirkn/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, Capt. Quirk wrote:

Markistuff,
K&N air filters sells a montor for jetting purposes
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2007\06\15@145257 by George Framen/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, George Frame wrote:

Capt. Quirk,
You are correct that Rod ratios for automotive applications are approx 1.8:1.  The length of the rod is dictated by many variables and trade-offs.  A rod that is short takes advantage of higher gas pressure earlier on the expansion stroke, the trade off here is the increased side loading on the piston, which increases engine friction, so there is no real gain.  I suppose the best way to get a handle on this is to look at the equation that relates cylinder volume to crank position (this includes the rod length). I have set up a little program to perform this calculation.  From this data you can plot cylinder volume vs crank angle with various rod lengths.  To see how much effect the rod has on this, I ran two cases: (1.) 6" Rod  and (2.) 12" Rod.  When I plot thes two cases the lines are so close together you can hardly see the difference.  So for automotive engines a fairly long rod gives the advantage of lower friction and better fuel ecomomy.  
For peak pressure location, I have looked at many different engines over my career as a engineer and they all (independent of size and geometry) are optimized when the peak cylinder pressure is at ~14 ATDC.  I would suspect, with a glow plug system, the mixture probably fires around TDC, yielding a peak pressure that is not  optimum, (it would be interesting to measure this).  It would be a good project to at least get the ignition system working for one of these engines that uses a glow plug, just to see if a single spark will beat a glow plug system. Try to get a long spark duration (3 ms).

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'[SX] Fuel Injection'
2007\07\17@142830 by Ibsenn/a
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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, Ibsen wrote:

Any progress on this project ???

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2007\07\17@144456 by markistuffn/a

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In SX Microcontrollers, SX/B Compiler and SX-Key Tool, markistuff wrote:

i havent really made to much progress lately.  its been running real good for about a month now. no real problems with the ecu.  i havent hooked up the electronic igintion yet or finished fine tunning the program code, but it runs way better then the carb i had on it.  so good infact ive broken 2 chains and im haveing real problems with my transmission.  guess with the engine is makeing more power now with efi so the other parts of the cart cant keep up.  thats mainly why i havent done more work on the ecu.  and im in the middle of building a wide band o2 controller.  almost have it done.  i think its alittle more complicated for me to build then the ecu was.

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