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Thread: ECM Test Bench

  1. #1
    Super Moderator Six_Shooter's Avatar
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    ECM Test Bench

    I have made and ECM test bench, that has been useful for testing code and learning about how ECMs function.

    I started with a MegaSquirt JimStim 2.0, and have made some jumper harnesses for different GM ECMs. I plan to use this to learn about other manufacturers ECMs as well.

    I started with the JimStim 2.0, since it had trigger wheel simulation, for simulating engine RPM.

    Here are some old pictures, I will get some new ones soon.







    Anyone else use a test bench?
    The man who says something is impossible, is usually interrupted by the man doing it.

  2. #2
    EFI GearHead ! EagleMark's Avatar
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    Re: ECM Test Bench

    Yeah I got one! Been building wiring harness on the bench and needed to test them, looked up some information and found that you had been doing ECMs on the bench.

    I added a JimStim stimulater to give some readings for sensors I couldn't get from the origanal test bench which was a TBI intake manifold. I used a distributor and a 3/8 drill to spin it.

    Been very handy both ways.

    Attached Images Attached Images

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
    -= =-

  3. #3
    EFI GearHead ! EagleMark's Avatar
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    Re: ECM Test Bench

    Here's a picture of one that Mark M, author of tunerPro uses. The stimulater was available years ago and is no longer available. But very cool set up!


    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
    -= =-

  4. #4
    Super Moderator Six_Shooter's Avatar
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    Re: ECM Test Bench

    Yeah, at one point, I was trying to find one of those, when I realized they were already long out of production.

    The JimStim works great though. Just needs a few more circuits.
    The man who says something is impossible, is usually interrupted by the man doing it.

  5. #5
    EFI GearHead ! EagleMark's Avatar
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    Re: ECM Test Bench

    The JimStim has been a great help but you have to add an EST like the one pictured above uses. You can get a tach signal without it but that's it, no knock or ESC. And if you hook up a 12 volt signal from the ECM to the JimStim you burn up a chip and a capiciter. (Don't ask how I know?)

    Have you seen the stimulater on Moates site for the Honda ECMs?

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
    -= =-

  6. #6
    Super Moderator Six_Shooter's Avatar
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    Re: ECM Test Bench

    I just have the ESC pulled own to ground through a resistor. I'm not so worried about testing ESC, at this point.

    Yeah, I've seen that stim, a bit pricey IMO, especially when a JimStim is so cheap and can do the same and more.
    The man who says something is impossible, is usually interrupted by the man doing it.

  7. #7
    Super Moderator dave w's Avatar
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    Re: ECM Test Bench

    Here is mine. I just plug everything in and spin the distributor with a hand drill. I use a hand vacuum pump on the Map Sensor, a heat gun on the temp sensor, and data log with the aldl connector. I ground a spark plug from the coil, and connect a noid light to the injector connector. The batteries are Sealed Lead Acid 12 Volt 10 amp / hour. I got the batteries from the recycle bin at work when the emergency lighting batteries were replaced.

    dave w








  8. #8
    Super Moderator Lucky's Avatar
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    Re: ECM Test Bench

    Now THAT looks like something I would do Dave

    no offense intended ...
    odd things the police have said to me; "you can't drive that on the road", "I like your cow", "I didn't think you would pull over so quick"

  9. #9
    EFI GearHead ! EagleMark's Avatar
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    Re: ECM Test Bench

    Here's a look at my power supply. Just a lawn mower batterey $22. and my batterey charger when needed. I also ran some power junctions to the benchtop when I am working. Jumper cable clamps at the batterey as I usually leave it disconnected when not in use.
    [attachment=0:wktck2b4]Power.jpg[/attachment:wktck2b4]


    Here is a close up of my JimStim wiring mess...
    [attachment=1:wktck2b4]JimStim.jpg[/attachment:wktck2b4]
    Attached Images Attached Images

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
    -= =-

  10. #10
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    Re: ECM Test Bench

    so how is everybody simulating an O2 sensor? that's about my only holdup ATM.

    i want to be able to control high/low time ratio and swing frequency independantly, so a 555 is pretty much out of the question.
    1995 Chevrolet Monte Carlo LS 3100 + 4T60E


  11. #11
    Super Moderator dave w's Avatar
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    Re: ECM Test Bench

    Quote Originally Posted by RobertISaar
    so how is everybody simulating an O2 sensor? that's about my only holdup ATM.

    i want to be able to control high/low time ratio and swing frequency independantly, so a 555 is pretty much out of the question.
    For a simple 1 wire O2 sensor I use an LM317 DC voltage regulator for 0vdc - 1vdc. http://www.national.com/mpf/LM/LM317.html#Overview

  12. #12
    Super Moderator Six_Shooter's Avatar
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    Re: ECM Test Bench

    Just a variable 10K resistor (pot), that is manually adjusted.
    The man who says something is impossible, is usually interrupted by the man doing it.

  13. #13
    EFI GearHead ! EagleMark's Avatar
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    Re: ECM Test Bench

    Quote Originally Posted by RobertISaar
    so how is everybody simulating an O2 sensor? that's about my only holdup ATM.

    i want to be able to control high/low time ratio and swing frequency independantly, so a 555 is pretty much out of the question.
    JimStim does narrow and wide band.

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
    -= =-

  14. #14
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    Re: ECM Test Bench

    Quote Originally Posted by Six_Shooter
    Just a variable 10K resistor (pot), that is manually adjusted.
    Quote Originally Posted by dave w
    For a simple 1 wire O2 sensor I use an LM317 DC voltage regulator for 0vdc - 1vdc. http://www.national.com/mpf/LM/LM317.html#Overview" onclick="window.open(this.href);return false;
    neither of these options would make the O2 swing though.... just provide an static mV value until manually adjusted.

    Quote Originally Posted by EagleMark
    JimStim does narrow and wide band.
    and i'm piecing this together bit by bit, since it will be incredibly cheaper and will allow me to tailor the bench specifically to the target ECM's capabilities.
    1995 Chevrolet Monte Carlo LS 3100 + 4T60E


  15. #15
    Super Moderator Six_Shooter's Avatar
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    Re: ECM Test Bench

    Test benches aren't meant to simulate a running engine, that would take much more complex processors and sim software than is readily available. This would require math that would simulate burn rates and changes within a cylinder, accounting for dynamics of a running engine.
    Test benches are meant to simulate static conditions that are otherwise impossible with a real engine to verify code changes or reactions of code to specific conditions.

    For the $59 (or so in kit form) from diyautotune.com, the JimStim is worth it to use as a base, since it can simulate quite a few different trigger wheels, though you really only need one, since most GM ECMs use the same ignition signals. That's why I started with the JimStim and have added on to it.
    The man who says something is impossible, is usually interrupted by the man doing it.

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