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

  1. #1
    Fuel Injected!
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    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
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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!
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    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!
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    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)

  7. #7
    Super Moderator dave w's Avatar
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    If I were to change computers, I would use the '0411 PCM. I've designed and built a plug-n-play crank position sensor kit to fit the L31 Vortec distributor, which makes upgrading to the '0411 very easy and affordable. See attached pics. Basically, the '0411 is flashed with a modified 2002 Express Van L31 5.7 liter tune. The crank position sensor kit, with new distributor, is on par with the cost of a MegaSquirt system.

    dave w
    Attached Images Attached Images

  8. #8
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    Quote Originally Posted by dave w View Post
    If I were to change computers, I would use the '0411 PCM. I've designed and built a plug-n-play crank position sensor kit to fit the L31 Vortec distributor, which makes upgrading to the '0411 very easy and affordable. See attached pics. Basically, the '0411 is flashed with a modified 2002 Express Van L31 5.7 liter tune. The crank position sensor kit, with new distributor, is on par with the cost of a MegaSquirt system.

    dave w
    If you dont mind me asking, Are you going to be selling these crank sensor kits?

  9. #9
    Super Moderator dave w's Avatar
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    Quote Originally Posted by Stokes1114 View Post
    If you dont mind me asking, Are you going to be selling these crank sensor kits?
    Yes, I will be selling the crank sensor kits. The production crank position sensor housing is 3D printed with Black High Temperature Glass Filled Nylon material, which is similar to the distributor cap ABS material. The prototype, which is pictured in my previous post, was 3D printed with a material called All Temp. http://www.goengineer.com/3d-design/...FRl2Xgod9pAPow

    dave w

  10. #10
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    Quote Originally Posted by dave w View Post
    If I were to change computers, I would use the '0411 PCM. I've designed and built a plug-n-play crank position sensor kit to fit the L31 Vortec distributor, which makes upgrading to the '0411 very easy and affordable. See attached pics. Basically, the '0411 is flashed with a modified 2002 Express Van L31 5.7 liter tune. The crank position sensor kit, with new distributor, is on par with the cost of a MegaSquirt system.

    dave w
    dave w this is awesome! I do 3d printing as well.
    Anyways couldn't this setup also be used in an lt1 with a modified intake for a conventional distributor? 0411 is multiple coils correct?
    I'm very interested in this. do you have a separate thread regarding this project?

    Thanks

  11. #11
    Super Moderator dave w's Avatar
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    Quote Originally Posted by johnny_b View Post
    dave w this is awesome! I do 3d printing as well.
    Anyways couldn't this setup also be used in an lt1 with a modified intake for a conventional distributor? 0411 is multiple coils correct?
    I'm very interested in this. do you have a separate thread regarding this project?

    Thanks
    I don't have a separate thread for the crank trigger kit.

    If the LT1 intake was modified to accept a conventional distributor, the distributor crank trigger kit I've developed could be used. The 2001 / 2002 Express Van Vortec L31 5.7 liter uses a 4 tooth (4x) crank trigger wheel. When moving the crank trigger to the distributor, the number of teeth on the trigger wheel needs to double. That's why my kit has an 8x trigger wheel.

    The '0411 coil on plug ignition system (distributor-less) uses a 24 tooth (24x) crank trigger wheel, which means a distributor mounted coil on plug trigger wheel will need 48 teeth. More Research and Development is needed to make a 48x trigger wheel work in the L31 distributor.

    dave w

  12. #12
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    I've had the battery disconnected many times, I just swapped the injectors from bank to bank because I have my wideband on the passenger side and narrow band on the drivers side and I wanted to see if the injectors are consistent and they are. So it's not the injectors. I tried several tunes I had in store today and each one definitely had their own personalities. Weird that a few days ago they all seemed to run identical. However even my known richest fueling tune the one from dyno day ran lean once I started driving it. My fuel pressure is good idling and revving up but I can't see what it's doing while driving. Is it possible to have good fuel pressure and have lack of flow getting to the injectors cause by a clogged fuel filter? I will be replacing the Fuel Filter tomorrow just in case. If that's not it I will have to suspect the Fuel Pump. I think I should mention I'm using an aeromotive fuel pressure regulator with guage right on the fuel rail.

  13. #13
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    How is this helpful Dave W?
    Last edited by Turbo Nasty; 10-11-2017 at 09:39 PM.

  14. #14
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    Quote Originally Posted by dave w View Post
    If I were to change computers, I would use the '0411 PCM. I've designed and built a plug-n-play crank position sensor kit to fit the L31 Vortec distributor, which makes upgrading to the '0411 very easy and affordable. See attached pics. Basically, the '0411 is flashed with a modified 2002 Express Van L31 5.7 liter tune. The crank position sensor kit, with new distributor, is on par with the cost of a MegaSquirt system.

    dave w
    How is this helpful?

  15. #15
    Super Moderator dave w's Avatar
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    My post was centered on the topic or comments about changing computers, MegaSquirt computer vs. Factory computer. Generally speaking, the Factory LS1b or '0411 computer is one of the best supported computers, including support from EFI Live and HP Tuners. It's very possible there are several tuners in your area that have extensive experience with the '0411. Maybe there are tuners in your area with extensive experience tuning with Megasquirt?

    I admit, my post did not mention any possible solutions that would be helpful to fix your engine.

    dave w

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