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Thread: 2005 Grand Prix 3800 Losing injector pulse

  1. #1
    Potential Tuner
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    Jul 2025
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    2005 Grand Prix 3800 Losing injector pulse

    Hi all, New to the forum.

    This engine is installed in a rock crawler. I was brought in by a friend who normally installs the earlier 3800's in the crawlers he builds. I was asked to come investigate why it will not start unless the battery is disconnected for at least 5 minutes.

    For info: the ECM was apparently reprogrammed by someone on the internet who won't return calls anymore and the tune looks a little strange to me.

    If I unplug the ECM for 5 min, it will start and run just fine. Sometimes just once, sometimes 5x in a row. I have checked the DTC's, the VATS has been deleted, but the problem persists.

    Things I have already verified when it fails to start:

    -It still has spark
    -It has fuel pressure
    -All ECM wiring is correct and verified with another harness


    When it does fail to start, the injector pulse is missing (verified with NOID light).

    Would you fine folks please look at the tune and see if I'm missing something? I'm at a loss for the cause and no amount of googling has helped me find any help.
    Attached Files Attached Files

  2. #2
    Senior Tuner
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    Nov 2017
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    And a log of it trying to start.

  3. #3
    Potential Tuner
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    Oh boy, I'll have to go back and get that. Sorry, I'm fairly new to this. I'll post it as soon as I can get back over there.

  4. #4
    Senior Tuner
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    Nov 2017
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    If you were logging when you tried to start, it automatically saves all logs.

  5. #5
    Tuner Vbb1994's Avatar
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    Mar 2023
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    Some sort of VATS problem maybe ?