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Thread: Help with capturing logs for transmission issue

  1. #1
    Tuner in Training
    Join Date
    May 2018
    Location
    Seattle
    Posts
    15

    Help with capturing logs for transmission issue

    First, I apologize as I'm new to tuning, and capturing logs. I've read the VCM Suite Scanner help, and done some searching to get an idea of how to configure and log the right data. But I feel at this point I'd be waving a flashlight around in the dark + a lot of trial and error / guessing

    I'm hoping someone on the forum here might be interested in helping analyze transmission logs / provide feedback ~ assuming I can capture the right info ~ which is the point of this post - what should I log? If there are some guides please link them, I like details, feel free to explain things in detail.

    At the very least I would like to get some idea of why these issues occur, even if its not "fixable" via tuning.

    Back story:

    • I have a 2013 Impala with the LFX engine and 6T70 transmission. Bought the car a couple years ago with 42k miles, trans fluid was dark, had it flushed by a reputable transmission shop.

    • Since then 3rd to 4th shifts are sometimes hard/shifts with a noticeable "bite" under light acceleration - usually if I have accelerated hard to moderately in 1st, 2nd and/or 3rd (e.g. giving it a quick windup from stop) then lifted off the accelerator.

    • The second issue are several short hesitation type feeling - like the transmission is preparing to shift and torque is being limited (wild guess here), then doesn't shift - it might do this 3 or 4 times in quick secession, again this happens under light acceleration in 3rd gear, easily repeatable and similar to the first issue - usually if I have accelerated hard to moderately then lifted off the accelerator, while this is occurring it will go away if I apply acceleration again, and it will sometimes be followed by the first issue - shifting to 4th with a bite.

    • Neither of the issues occur if I accelerate normally through hard with out lifting off - shifting is normal.

    • If I disconnect the battery to clear anything learned, transmission performs nicely, with less "slop" in the shifts until the adaptives are set/learned again and the issues come back.
    Last edited by Weasel; 09-16-2018 at 09:18 PM.