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Thread: COS3 popping into closed loop even though I'm not commanding 14.68

  1. #1
    Junior Member
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    Default COS3 popping into closed loop even though I'm not commanding 14.68

    Hi, I'm running COS3 on a 2002 zo6 vette and I have an issue with the car going lean from time to time for a short period. During this period where it goes lean the car will command 14.68 even though my commanded AFR table doesn't have 14.68 anywhere in it. I have 14.8 in it and 14.5, but nothing close to 14.68 in it. I believe it looks at the STFTs when it commands 14.68 which is causing the lean blip, but I can't figure out why it is commanding 14.68. It seems to do it for about a second as the car is getting up to temp. Please let me know if there's anything I can look into.

    Thanks a lot in advance
    Brian

  2. #2
    Lifetime Member Chevy366's Avatar
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    My theory is the PCM is doing a MAF or O2 check and goes into a brief error check mode and then falls back to SD .
    Last edited by Chevy366; June 12th, 2009 at 10:53 AM.
    2005 1500 HD , Custom OS3 SD tune .
    2006 Trailblazer
    Dinosaurs and Plants gave their lives so that we may drive , long live fossil fuel .

  3. #3
    Joe (Moderator) joecar's Avatar
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    Post some log files.

  4. #4
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    bump Ive got the same problem(ls1 cos3)...when it reaches 14.63 from cold start the stft wont re correct and continue to lean to(20:1) until the spark overshoot corrects idle speed then bumps back to (10;1)to me it seems that its only deducting maybe its doing its role from the information provided (o2 switch points) or on a previous thread lean cruse interfering?

    http://forum.efilive.com/showthread.php?t=10738
    Last edited by drdarthinvader; June 13th, 2009 at 02:38 AM.

  5. #5
    Lifetime Member hymey's Avatar
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    set 02 enable to 140 try that

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