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Thread: Real WOT Shift Points Lower Than Commanded, Stuck

  1. #1
    Senior Tuner
    Join Date
    Nov 2002
    Location
    Central Florida
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    2,503

    Real WOT Shift Points Lower Than Commanded, Stuck

    I encountered some strange shifting behavior (WOT
    2-4, way lower shift RPM than programmed). At
    the time I logged this there were no codes or any
    indication why.

    Two throttle codes popped later in the week, the
    P0123 put me onto the TPS voltage which was all
    the way up to 4.95V at WOT. I had removed the
    stop screw on the new Professional Products TB
    to get over-center opening (blade parallel to the
    bellows which is bent).

    I tweaked it back to 4.70V max and the car is now
    shifting as commanded.

    I believe that TPS voltage greater than the 4.75V
    fault threshold makes the trans shifting go to some
    kind of failsafe, shift-early mode. And that this may
    be at the root of a lot of these "my shiftpoints are
    too early and don't change" problem reports. It
    seems like a real-time thing, not needing a code
    set to start messing.

    If you are not seeing WOT shifts moving with your
    programming changes, monitor your TPS -voltage-
    (not %) and be sure it is consistently below 4.75V
    at WOT.

  2. #2
    Tuner
    Join Date
    Oct 2005
    Location
    Dubai,United Arab Emirates
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    Thanks for the tip
    03 Mercedes ML55 AMG - Stock
    06 S2000
    06 GMC Sierra 3500 - Tuned
    09 GT-R - Stock
    09 Lexus LX570
    10 Camaro SS , Bolt Ons , Tuned

  3. #3
    Advanced Tuner Bluecat's Avatar
    Join Date
    May 2006
    Location
    Catlettsburg, Ky
    Posts
    407
    I see that all the time on LT1 cars with aftermarket TB's. I saw it so much for a while that I make it standard procedure to delete tps high voltage code.