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Thread: 48re Shifting issue

  1. #1
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    48re Shifting issue

    I have been messing around with tuning my truck for a little bit now. Seems to be doing ok.. but one issue I have is my truck isnt wanting to downshift to 1st gear at a stop unless I put it in manual 1... also doesnt like to kickdown when going full throttle... When Switching my tunes to a known good one. the transmission acts normal and shifts good. Truck is an 06 with transgo shiftkit TTVA. I have not touched any of the transmission setting in my tune



    tune-attempt 3.hpt

  2. #2
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    Quote Originally Posted by NRunkle View Post
    I have been messing around with tuning my truck for a little bit now. Seems to be doing ok.. but one issue I have is my truck isnt wanting to downshift to 1st gear at a stop unless I put it in manual 1... also doesnt like to kickdown when going full throttle... When Switching my tunes to a known good one. the transmission acts normal and shifts good. Truck is an 06 with transgo shiftkit TTVA. I have not touched any of the transmission setting in my tune



    tune-attempt 3.hpt
    I remember having an issue with the trans in my truck after disabling the "Trans Limit" ([ECM] 7870, follow the path ---> Engine - Diesel Fueling - Main Injection Limits). I just don't recall what the symptoms were. Try re-enabling that limiter with no other changes, see if that fixes your issues.

  3. #3
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    Ok I will give that a shot! I enabled it and then maxed the table out. Thanks!

  4. #4
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    Quote Originally Posted by B00STJUNKY View Post
    I remember having an issue with the trans in my truck after disabling the "Trans Limit" ([ECM] 7870, follow the path ---> Engine - Diesel Fueling - Main Injection Limits). I just don't recall what the symptoms were. Try re-enabling that limiter with no other changes, see if that fixes your issues.
    I have loaded the map with the limiter re-enabled, shifts good other than I am having an issue where the 3-4 shift is a little delayed at WOT and going past my upshift rpm settings, Also what tables would I just to change what mph the 1-2, 2-3 shifts occur? Thanks

  5. #5
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    Quote Originally Posted by NRunkle View Post
    I have loaded the map with the limiter re-enabled, shifts good other than I am having an issue where the 3-4 shift is a little delayed at WOT and going past my upshift rpm settings, Also what tables would I just to change what mph the 1-2, 2-3 shifts occur? Thanks
    The parameters you seek aren?t visible. Your governor pressure will change the shifts from gears 1 through to 3 but to a very limited degree and not very consistent results without access to the hidden parameters. TTVA will have an effect on when those shifts occur, both gov pressure and TTVA angle also affect shift firmness.

  6. #6
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    Quote Originally Posted by Jim P View Post
    The parameters you seek aren?t visible. Your governor pressure will change the shifts from gears 1 through to 3 but to a very limited degree and not very consistent results without access to the hidden parameters. TTVA will have an effect on when those shifts occur, both gov pressure and TTVA angle also affect shift firmness.
    Ok, I am looking at the TTVA positions.. Its reading 51 degrees at 100% Throttle, is that correct? Max degree i can go is 100?

  7. #7
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    Sounds right for stock, that?s not why there is delays at WOT. There is actual delays in the programming plus other stuff going on.

  8. #8
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    Quote Originally Posted by Jim P View Post
    Sounds right for stock, that?s not why there is delays at WOT. There is actual delays in the programming plus other stuff going on.
    Ok what other things could I look at? also if I go to 100 degree at 100% it will give me max line pressure that the transmission can produce?

  9. #9
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    You already got the max line pressure the transmission can produce. Without the hidden parameters there isn?t much you can do to get the transmission to do exactly what you want every single time. There?s only two people (tuners) out there aside from Chrysler and Cummins engineers that know exactly what to do to gain consistent control of the transmission.