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Thread: Need help tuning 6L50 - T43

  1. #1
    Junior Member
    Join Date
    Mar 2007
    Posts
    19

    Default Need help tuning 6L50 - T43

    I am not new to tuning or to EFI Live but I cannot figure out how to tune this trans in a 2016 Colorado. In drive it shifts 1-2 between 6200-6400 RPM, in tow/haul mode it always shifts at 6800 RPM. In addition in tow/haul mode the trans will not go into 6th gear. In looking at the tables I assume drive = Normal shift pattern and tow/haul = Pattern A (Pattern B is disabled). My goals for the tune are:
    1) Raise 1-2 shift point in normal pattern to 6800 rpm
    2) Raise part throttle upshift points (TPS < 25%) so engine is not lugging at 1000 rpm
    3) If possible shorten and firm up shifts a bit

    I have gone through all the trans tables and cannot find where they are actually controlling the 1-2 shift at WOT. In the Normal or Pattern A Part Throttle Shift tables the 1-2 shift is supposed to occur at 34 MPH for both patterns but in reality they occur at 39 and 43 MPH. The Normal and Pattern A WOT Shift Speeds has a 1-2 shift at 30 and 40 MPH respectively. WOT Shift RPM for both normal and Pattern A is set to 6800 rpm. So if the WOT Shift RPM table allows shifts at 6800, and the WOT and Part Throttle Shift tables show values below actuals, what is controlling the shift? If I can get this figured out I will know which table to changes for the part throttle upshifts (below 30% TPS).

    I have heard that this trans is not as easy to tune as the 4L60 I am used to (decrease shift times by 0.1 seconds and increase line pressures by 10%). Any advice on how to shorten shift times and firm them up a bit.

    Any advice would be appreciated. Stock TCM tune file is attached.
    Attached Files Attached Files
    2004 GMC Envoy 5.3L - Modified
    2016 Chevy Colorado Z71

  2. #2
    Lifetime Member Tre-Cool's Avatar
    Join Date
    Feb 2006
    Posts
    937

    Default

    comparing to my diesel colorado D9605 is set to 5th in yours vs 6th in mine. however we tapshift and no haul mode.
    D9601 is also enabled vs disabled on mine.

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