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Thread: 4L60e will not shift 1-2 @ wot

  1. #1
    Tuner in Training
    Join Date
    May 2009

    4L60e will not shift 1-2 @ wot

    I have a 1979 C10 truck with a 4.8L/4l60e swap (all stock except for rocker trunion upgrade), using a 2004 Avalanche PCM and factory harness to control engine/transmission. To the best of my knowledge I have everything correct (as I know it) for the setup (PE with wideband, MAF, gearing, tiresize, etc.).

    However, I have always had trouble with the 1-2 shift at wot. While in 1st, going wot, it will peg the limiter, and will not shift until I let off the gas. Part throttle shifts are great, no issues at all. No codes are being thrown.

    I have gone forum to forum looking for an answer, and have found/then tried potential solutions. I swapped in new TPS, MAF, and VSS sensors which did not fix the shift issue. I have ran different cooling line/trans cooler setups, to ensure no line clogs or pressure issues which did not fix the issue. I then changed out fuel lines, fuel filters, fuel pump, and fuel pump wiring all to ensure no fueling/fuel pressure problems which did not fix the issue. I even went as far as getting a completely different 4l60e transmission, and again no luck, same no 1-2 shift issue.

    So now Im reaching out for someone to look into the tune. I have tried a few different tweaks, and lowered commanded speed/rpm at wot, but still cannot get it to shift 1-2 at wot no matter what I do.

    Maybe Ive got something totally screwed up. Anyway, Ive attached some logs and my tune in hopes someone can tell me what Im doing wrong here.


    no shift.hpl

    no shift 1.hpl

    79 C10 Current NEW Trans Stock 1.hpt

  2. #2
    Senior Tuner Russ K's Avatar
    Join Date
    Dec 2005
    Regina, Sask.
    The throttle is closing at 3900 RPM. Disable the ETC limit in the Cutoff, DFCO tab.

    Russ Kemp

  3. #3
    Potential Tuner
    Join Date
    Jul 2016
    Im having the same problem but i have a cable TB. I also noticed that the trans temp is reading -38 could that be the problem?

  4. #4
    Advanced Tuner
    Join Date
    Feb 2015
    Perth, Australia
    disable abuse mode and populate the D1 and D2 urban shift tables with the same as normal table