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Thread: 4L80e Problems - Wont downshift once in 3rd

  1. #1
    Potential Tuner
    Join Date
    Feb 2020
    Posts
    6

    4L80e Problems - Wont downshift once in 3rd

    I have a Chevy K20 with a LS3 and 4L80e and a NP208 transfer case. I have a Dakota Digital 16k speed sensor in the transfer case with their signal converter outputting 128k signal to tcm. E38 and T42 controllers. When accelerating from a stop it will shift up thru the gears, but not at the commanded shift points and then it won't downshift lower than 3rd, until almost at a complete stop and trying to kill the engine at that point. I've tried the attached file and a stock 4L80e file from a 2008 express van out of the repository with the same results. Can anyone take a look to see what's going on?

    Thanks

    84 Chevy K20 LS3 4L80e 081723 353pm.hpt
    84 Chevy K20 LS3 4L80e 081723 421pm.hpl

  2. #2
    Advanced Tuner
    Join Date
    Mar 2009
    Location
    Andover, MN
    Posts
    497
    Well at 0 throttle downshift matches upshift speed. try adjusting that first