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Thread: 6L80 Keeping Converter Locked For Closed Throttle Shifts

  1. #1
    Tuner in Training
    Join Date
    May 2016
    Posts
    26

    6L80 Keeping Converter Locked For Closed Throttle Shifts

    Hi all,

    A little background. My car is a 2013 Corvette with H/C/I/E/Meth. I'm running a Pro Torque 3200 3-disk carbon converter that holds lock no matter what - low throttle, WOT, during upshifts, etc.

    I have been struggling for literally years with a strange issue. The converter will not stay locked for shifts at very low throttle (foot off the pedal). With a bit of throttle, there's no issue. I've tried enabling "shift lock" and get the same behavior - I'm inclined to think there's something odd in my tune, but I'm just not sure where to look.

    I believe this issue also prevents staying locked during downshifts - this is the real issue I have been fighting. When slowing down and downshifting from 4->3, the converter unlocks, RPMs drop, then the converter re-locks, which is quite jerky. In this situation, "shift lock" DOES work for me, but ONLY if I am giving a bit of throttle - if the throttle is fully closed, the converter will unlock, shift, relock per usual.


    I've attached my current tune and 2 logs.

    The 07-21-2020 log is from today with "shift lock" enabled. Note that this log has some weird moments with poor sampling due to some other traffic on OBD2 (Radar detector).

    You can see the closed throttle downshift issue around the 08:17 time mark (4->3 shift with unlock, shift, relock). You can see the behavior when throttle is applied at the 8:28 mark (4->3 with no unlock); the only apparent difference is the throttle that is applied.

    The low-throttle upshift issue can be observed at 06:53 in the 07-12-2020 log (3->4 unlock, shift, relock). A normal upshift can be seen at the 08:20 mark (3->4, no unlock).

    Any advise or insight is greatly appreciated!



    NJE SL 001.hpt07-12-2020-01.hpl07-21-2020-01.hpl

  2. #2
    Tuner in Training
    Join Date
    Aug 2019
    Posts
    14
    Did you ever figure this out? I'm trying to keep my triple disc converter locked on the WOT 2-3 shift, but it will always unlock, then lock after the shift. Really scratching my head on this as I also have Shift Lock enabled.

  3. #3
    Tuner in Training
    Join Date
    May 2016
    Posts
    26
    No, no progress on this front, and eventually I just stopped messing with that part of the tune, disabled shift lock, and set up the lock tables to essentially only lock while accelerating to remove any jerkiness when downshifting.

    I've never tried locking in 2nd, but I have not had any issues with the converter staying fully locked from 3-4, 4-5 at any throttle position or RPM (except for zero throttle upshifts, which is the same issue as originally described. I just make a point of not upshifting without throttle whenever possible).

    Based on the research I've done, I think these types of issues are entirely due to differences in the actual lockup logic code within the OS, and not something that is accessible by any calibration table by any tuner. Short of having access to the actual firmware for the controller, we just get to live with these quirks..

    This particular one is something that I never remember noticing before my high stall converter, but I suspect that's because the factory converter is essentially always stalled.