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Thread: Random lean spikes after letting off throttle

  1. #1
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    Default Random lean spikes after letting off throttle

    I installed a 4L80E and a new converter and noticed an issue on the highway. Sometimes when I let off the throttle I will get a very lean spike, almost like the engine it trying to die, but it will catch itself. Sometimes it happens many times in a row. It is more common after some medium-heavy throttle.

    Fuel pressure looks good, but the IBPW drops very low causing the lean spike. And ideas where to look in the tune for a cause?

    I had a T56 before and it never did this.
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    2001 Silverado 5.3L ECSB 2WD T56:
    T76 turbo, Meth injection, 72# injectors, 799 heads, 212/212 114LSA cam, Built 4L80E, 3.42's
    EFILive V1 Commercial, COS5 2-bar SOLSD, AEM wideband

  2. #2
    Lifetime Member 5.7ute's Avatar
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    Hi Mike.
    I would first check all of your DFCO settings.
    Also log G/CYL to see if there is a glitch in the airflow model causing it to command such a small pulsewidth.
    The Tremor at AIR

  3. #3
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    Mick,

    DFCO is disabled at the moment.

    I'll log airflow tomorrow morning.

    Here is the log that screenshot came from. It's mostly trans PID's.
    Attached Files Attached Files
    2001 Silverado 5.3L ECSB 2WD T56:
    T76 turbo, Meth injection, 72# injectors, 799 heads, 212/212 114LSA cam, Built 4L80E, 3.42's
    EFILive V1 Commercial, COS5 2-bar SOLSD, AEM wideband

  4. #4
    Lifetime Member 5.7ute's Avatar
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    Quote Originally Posted by ferocity02 View Post
    Mick,

    DFCO is disabled at the moment.

    I'll log airflow tomorrow morning.

    Here is the log that screenshot came from. It's mostly trans PID's.
    No worries.
    Send the tune file through to my email if you don't want to post it up.
    The Tremor at AIR

  5. #5
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    Durrrrr. DFCO was enabled. I had disabled it in different tune to work on the VE table
    2001 Silverado 5.3L ECSB 2WD T56:
    T76 turbo, Meth injection, 72# injectors, 799 heads, 212/212 114LSA cam, Built 4L80E, 3.42's
    EFILive V1 Commercial, COS5 2-bar SOLSD, AEM wideband

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