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Thread: That's it! I'm effing done with this ECU! Going to megasquirt!

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  1. #1
    Fuel Injected!
    Join Date
    Nov 2016
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    66

    That's it! I'm effing done with this ECU! Going to megasquirt!

    1990 corvette with built motor and 32lb injectors. I'm so done with the crap from trying to tune this stock ecu. I never got it to enrich AE properly, it will not cut fuel off the throttle no matter what I do, it randomly kicks up my idle really high sometimes when I start it, I have to turn it off and restart, but far worse than any of that it will randomly lean out my tune like it's got a mind of it's own and it stays that way until I reflash the chip. But now even that won't fix it! So I'm done with it! It's so lean it's not driveable. I'm going to get a megasquirt. I'm not sure which one I'm going to get yet. maybe you guys know one that's ideal for a 1990 corvette or have done one already. Thanks!

  2. #2
    Super Moderator Six_Shooter's Avatar
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    You'll probably have the same problems with Megasquirt. It sounds like you probably have a mechanical issues or a few.
    The man who says something is impossible, is usually interrupted by the man doing it.

  3. #3
    Fuel Injected!
    Join Date
    Nov 2016
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    I've already looked into that. Fuel pressure is good, timing is good, all of the injectors appear to be working fine. I may send them back to get tested and inspected though just to be sure. But I think they are okay. This is a new engine as of early this year, new fuel pump and filter, injectors are flow matched bosch type 3 32lb rebuilt from fuel injection connection. And how do you explain my tune changing and going lean some days and then not being able to fix it unless I retune my fuel maps or reflash the chip? Then a few weeks later I have to do it again.

  4. #4
    Super Moderator Six_Shooter's Avatar
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    I don't think it's your "tune changing". I think it's something mechanical that's getting worse and re-uploading a bin resets any stored learn trims. Tunes don't just "change on their own", which again leads back to a mechanical issue. The fact that re-uploading the bin isn't fixing it now, is also a good indicator of this.

    I've seen this same post so many times and in every case it turned out to be not ECM related.
    Last edited by Six_Shooter; 10-08-2017 at 09:48 PM.
    The man who says something is impossible, is usually interrupted by the man doing it.

  5. #5
    Fuel Injected!
    Join Date
    Nov 2016
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    66
    What do you think I should check out? The fuel pressure goes up when I rev up the engine so I think the fuel pump should be good. Injectors all sound and feel like they are working. I took the passenger side injectors out to see if they were clogged but they look fine. I'll check the others tomorrow.

  6. #6
    Fuel Injected!
    Join Date
    Jun 2016
    Location
    Charleston, SC
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    46
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    152
    I think a good first step might be to disconnect power to the ECM (disconnect battery entirely) and let the ECU clear, then see what happens when you reconnect. This would clear out the stored learn trims, would it not?

    Concur your problem is likely to be mechanical, not ECM. You're running a GM motor with a GM ECM. They WILL play nicely together, as has been exhibited thousands of times with enthusiast builds. It's time to start with the fundamentals and build from there. I'm sure you're an accomplished wrench, and this seems silly- but this is where the problems lie, 9 times out of 10. I speak from experience.

    Don't be big-headed about it, don't take this as offense. Be honest with yourself and don't assume "well of COURSE I did "x" right, I've done it a lot of times before". *Check and verify*.

    I am in a similar boat. I have a stock 350 in a commonly-swapped frame (S10) using GM ECM made for the purpose.. and it's running like crap. So I have backed off to ground zero and am checking everything anew.
    -Phil, in Charleston, SC

    '89 S10 Blazer: SOA SAS: Dana 44s, 5.7L V8, 700R4; 35s, 4.10:1; TBI with 1227747 ECM
    '94 Grand Cherokee: 4.0, 4" lift, 31s
    '90 Jeep Cherokee: In progress: 5.7L V8,700R4,NP231C, D44s. TBI with 1227747 ECM
    '87 Fiero GT: 3.8SC (initial research stage)

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