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Thread: E78 AC Compressor Spark Retard?

  1. #1
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    Default E78 AC Compressor Spark Retard?

    Guys just curious if there are any tables that affect the spark related to the AC such as the Gen III ECMs did in table B4358?
    Reason I ask is on a level cruise I noticed a few time where the TQ Spark Red Commanded jumped up considerably for no apparent other reason. Level cruise 75MPh, no changes in engine airflow/throttle/fueling/loads. TCC was locked the entire time in 6th gear as well.

    Thanks in advance.
    Vehicle is 2011 GMC 2500 HD 6.0/6L90

  2. #2
    Lifetime Member GMPX's Avatar
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    Probably but it would come via a torque reduction request rather than a specific A/C spark table (I'm assuming).
    I no longer monitor the forum, please either post your question or create a support ticket.

  3. #3
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    Yep it is just logged and tested it on the freeway. Now the question is why cut power to engage a load?? So we really feel it ... GM logic escapes me on this one. Anyone know how to disable it? I cycle the AC and it dips 20 degrees each time I flip he AC back on.

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