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Thread: Engine dieseling on shut down

  1. #1
    Advanced Tuner angrygoat's Avatar
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    Oct 2008
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    Engine dieseling on shut down

    I have a friend's GTO that will diesel a little once in a while when we shut it down. Every few shut downs, the car with huff a couple of times when the key is turned off.

    The basic setup is 235/240 cam with trickflow heads and a vic jr. Assuming everything mechanical is good, is there something in the tables that would cause this. TIA
    Joe
    2006 M6 GTO
    APS TT
    10.76@131

    "The goal of tuning is for the tune to run well enough you dont need any corrective mechanisms"

  2. #2
    Tuner in Training
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    Aug 2009
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    Quote Originally Posted by angrygoat View Post
    I have a friend's GTO that will diesel a little once in a while when we shut it down. Every few shut downs, the car with huff a couple of times when the key is turned off.

    The basic setup is 235/240 cam with trickflow heads and a vic jr. Assuming everything mechanical is good, is there something in the tables that would cause this. TIA
    Yes too much timing or too much fuel at idle.

  3. #3
    Senior Tuner Mep_q8's Avatar
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    Mar 2006
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    what he said..

    Bader Norris
    MEP Tuned
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  4. #4
    Senior Tuner
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    Jun 2007
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    Too rich at idle will leave fuel in the cylinders at shutdown and help cause this. Too rich also leads to carbon coating the pistons and combustion chambers, which increases compression.

    I would recommend seafoam the top end and then do a closed loop STFT VE/MAF tune session to dial in AFR.