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Thread: wot 2-3 shift on limiter

  1. #1
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    Default wot 2-3 shift on limiter

    I am running into trouble with a 6.0 4l80 combo hitting limiter on 2-3 shift it is not being commanded I've tried everything i can possibly think of wot set to 4800 I've tried 4000 it just wont command until 93mph I am running it in 4 low 5.13 gears reading from trans output vss wondering if its just not possible for the pcm to shift fast enough. tune and log posted 0411 512k cos
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  2. #2
    Joe (Moderator) joecar's Avatar
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    I'll look at your tune when I get home.

    In your tune did you correct the speedo for your gear/tire...?

    ~Moderator~

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    Quote Originally Posted by joecar View Post
    I'll look at your tune when I get home.

    In your tune did you correct the speedo for your gear/tire...?

    ~Moderator~
    Yes but it reads wrong when I'm in low range which shouldn't bother anything I just sold my other jeep with the same setup but 4.10 gears and 1mb pcm that worked fine

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    If you look at the log commanded gear it's on limiter for a while before it even commands 3rd, pcm too slow? I'm stumped and I race up a snow hill in a week. might try changing to a 1mb. one thing I forgot to do was Dvt control I'll try that when I get home tomorrow.

  5. #5
    Joe (Moderator) joecar's Avatar
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    The PCM is not slow, it's being fed incorrect data and/or its tables are incorrect.

    ~Moderator~

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    Quote Originally Posted by joecar View Post
    The PCM is not slow, it's being fed incorrect data and/or its tables are incorrect.

    ~Moderator~
    So you obviously see something wrong in the tuning side of it? I've done a bunch of logging and tuning what should I be logging that I'm missing?

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    nobody? nothing surely there has to be a fix for this? I've searched everywhere Ive tried all I can find

  8. #8
    Joe (Moderator) joecar's Avatar
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    Sorry, I have been delayed... I'm still looking thru your tune file.


    What axle ratio and what tire size do you run...?

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    Quote Originally Posted by joecar View Post
    Sorry, I have been delayed... I'm still looking thru your tune file.


    What axle ratio and what tire size do you run...?
    I have 5.13 gears 35" tire like I Said before I am running 4 low but reading speed before transfer case. I have a race Saturday and am pulling my hair out. if I let off throttle slightly at the right time it will shift, any help would be much appreciated thanks

  10. #10
    Joe (Moderator) joecar's Avatar
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    Your WOT upshift/downshift MPH values are upside-down, including the WOT 2->3/3->2 values

    the downshift MPH has to to be lower than the corresponding upshift MPH
    e.g. your D0930,31,32,64 are set to 60,60,66,30; your D0915,16,17,67 are set to 20,20,55,25; these are upside-down, this will prevent WOT upshift in any mode of the 4 modes.

    Same with your PT 1->2 and PT 2->1 tables.

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