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Thread: Spark TQ Ratio Settings can Affect Fuel Source

  1. #1
    Senior Tuner CCS86's Avatar
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    Spark TQ Ratio Settings can Affect Fuel Source

    Just wanted to share some interesting behavior.

    I was trying to limit the amount of spark retard after a quick pedal blip while idling (goes to ~ 12* ATDC)

    It seemed obvious to use the Spark TQ Ratio Limit and Spark Only TQ Ratio. Based on the setting descriptions, "Spark Only..." went from 0.000 to 1.000; and "Spark...Limit" went from 0.500 to 1.000; in theory disabling any spark reduction for "Target N" (which was the torque source during the retardation).

    Not only did this have zero impact on the spark reduction; it actually cause a roughly 9 second period of open loop fueling, following the blip; where it stays closed loop with the stock settings.

    Maybe someone has a better explanation of these settings, which matches this behavior:

    spark tq ratio blips.jpg

  2. #2
    Senior Tuner CCS86's Avatar
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  3. #3
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    Quote Originally Posted by CCS86 View Post
    Logs of each:
    I'm not surprised about injector lean/cut since you took the spark authority away but I am surprised it made no difference in spark. I'm just as curious as you
    Knock Retard is the reduction or prevention of knock by lowering ignition timing:

    (+) Adding Knock Retard = Reducing Timing. PCM is seeing knock.
    (--) Lowering Knock Retard = Increasing Timing. PCM isn't seeing knock.
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