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Thread: e38 ls7 - bucking at ~1500 rpm timing erratic

  1. #1
    Tuner in Training
    Join Date
    Mar 2021
    Posts
    12

    e38 ls7 - bucking at ~1500 rpm timing erratic

    Hey Guys,

    I have been doing a lot of VE table refining and have the car driving and somewhat idling decently after doing a whole top end.

    I looked at my base timing tables high/low octane are the same and looked at my idle timing/ coastdown timing table as well and cant seem to pin point what is causing my timing to be erratic around 1500 rpm.

    During parking lot maneuvering or very low rpm cruising, the car bucks/surges a bit and i notice that the timing is swinging over 15 to 20 degrees. Is there a timing retard that is activating that i am overlooking?

    Once i get this squared away, the car will be ready for some dyno tuning to finish it up.

    I attached some files
    Attached Files Attached Files

  2. #2
    Advanced Tuner
    Join Date
    Aug 2010
    Location
    Detroit, MI
    Posts
    926
    Probably the air calc mode hung up in normal transition mode. Why do you have your MAF disabled anyway? Re-enabling the MAF will solve this the simplest way...

  3. #3
    Tuner in Training
    Join Date
    Mar 2021
    Posts
    12
    Hey Smokeshow,

    I am running in speed density as i am still fine tuning the VE table.

    When i had the MAF enabled, it ran so bad that the car wouldnt even drive down the block without going into reduced engine power mode and giving me TB DTCs and MAF DTCs.

    The car has an ls7 with a full top end on it that i finally have tuned with great street manners EXCEPT this timing surge. I tried matching the idle timing and Hi octane/low octane tables in that region with no change.