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Thread: T43 Tuning

  1. #1
    Tuner in Training
    Join Date
    Jun 2016
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    44

    T43 Tuning

    Hi guys,

    Can someone take a look at this log. There are things I don't understand. From the 1 to second upshift, the timing is being pulled back before the actual shift and it gets re-introduced and only after that the tranny shifts. Then at 6600 rpm in second gear the timing is being pulled back again and the rpm's fall back to 4300.

    the upshift from second gear to third is weird too, I have some slip then no timing pull to engage the third gear.

    Also, the TCC slips a lot during the third to fourth transition.

    Thanks

    wotshifting.hplTranny_tccpressure20%.hpt

  2. #2
    Tuning Addict 5FDP's Avatar
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    May 2012
    Location
    Rogers, MN
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    9,962
    The slower shift times and timing being pulled is completely normal for a stock calibration.

    Just look at the shift timing tables and you'll see how slow they are set. Shift timing > torque adder > normal. Those are your shift time tables.

    In a heavy truck I keep the lower torque cells around .4000 instead of .6000 to .7000 and then I lower the higher torque cells to .3000 max because I do not want to hurt anything. You can go through those tables and lower the values but keep the stock like "curve" still there to keep the shifting smooth. I generally don't mess with 5th and 6th gear much as they are over drive gears and the skip shifts are normally pretty quick as they are in stock form.

    This truck shows pattern X as the normal shift pressure tables. So if we go into upshift pressure pattern X, you can slightly adjust the shift pressure. The high torque cells are already plenty high and I add maybe 5-10% to the lower torque cells to help improve normal and medium throttle shifting.

    Next, look at the adaptive settings. The oncoming pressure presets can be increased slightly to help as well. Again I go slow here to creep up on what I want. Start with 5-10% and work it from there.

    I also do not like having the torque converter locked in gears 1-4, so I disabled that and to me it runs way smoother. I also play with my torque lock up speeds for the gears so it can't lock up in 5th gear at 35-40mph and feel like it's lugging around. Raising them up to 45-48mph got 5th gear and 50-55mph for 6th gear makes it way better to drive.

    You can reduce the amount of negative timing being pulled too. Timing still should be pulled but going back to -12 or -20 is a bit much. Making it -5 to 0 degrees should still be just fine.

    Just to note two other things here. The airflow model and torque model being spot on is one key to making the transmission do what you ask of it. If that is kinda jacked up it will throw things for a loop. And lastly, when you make transmission changes such as pressure changes or on-coming pressure presets you must reset the adaptive learning with the VCM scanner after flashing the file and prior to starting the vehicle again. So flash the file with the changes, open the vcm scanner, connect and start logging. In the VCM controls > transmission there are two boxes called something like adapts preset and reset. Click reset first and then preset, now it will re-learn the settings and it will shift kinda funky for a few miles as it goes through the gears.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

  3. #3
    Advanced Tuner
    Join Date
    Apr 2017
    Location
    Meridian MS
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    672
    As far as I know you can't change the duration of the timing pulled during the shift, so the solution is to make the shift complete before the timing/engine power comes back up enough to create slip. When the timing is down below zero and it's making basically no power you can make it shift really damn fast and it won't hurt anything, as long as it's finished before timing is restored.

  4. #4
    Tuner in Training
    Join Date
    Jun 2016
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    44
    Quote Originally Posted by 5FDP View Post
    The slower shift times and timing being pulled is completely normal for a stock calibration.

    Just look at the shift timing tables and you'll see how slow they are set. Shift timing > torque adder > normal. Those are your shift time tables.

    In a heavy truck I keep the lower torque cells around .4000 instead of .6000 to .7000 and then I lower the higher torque cells to .3000 max because I do not want to hurt anything. You can go through those tables and lower the values but keep the stock like "curve" still there to keep the shifting smooth. I generally don't mess with 5th and 6th gear much as they are over drive gears and the skip shifts are normally pretty quick as they are in stock form.

    This truck shows pattern X as the normal shift pressure tables. So if we go into upshift pressure pattern X, you can slightly adjust the shift pressure. The high torque cells are already plenty high and I add maybe 5-10% to the lower torque cells to help improve normal and medium throttle shifting.

    Next, look at the adaptive settings. The oncoming pressure presets can be increased slightly to help as well. Again I go slow here to creep up on what I want. Start with 5-10% and work it from there.

    I also do not like having the torque converter locked in gears 1-4, so I disabled that and to me it runs way smoother. I also play with my torque lock up speeds for the gears so it can't lock up in 5th gear at 35-40mph and feel like it's lugging around. Raising them up to 45-48mph got 5th gear and 50-55mph for 6th gear makes it way better to drive.

    You can reduce the amount of negative timing being pulled too. Timing still should be pulled but going back to -12 or -20 is a bit much. Making it -5 to 0 degrees should still be just fine.

    Just to note two other things here. The airflow model and torque model being spot on is one key to making the transmission do what you ask of it. If that is kinda jacked up it will throw things for a loop. And lastly, when you make transmission changes such as pressure changes or on-coming pressure presets you must reset the adaptive learning with the VCM scanner after flashing the file and prior to starting the vehicle again. So flash the file with the changes, open the vcm scanner, connect and start logging. In the VCM controls > transmission there are two boxes called something like adapts preset and reset. Click reset first and then preset, now it will re-learn the settings and it will shift kinda funky for a few miles as it goes through the gears.
    Thanks a lot for the reply ! I got it shifting properly now. I also put the "speed ctrl terminate" tab to immediate. Your explanation was spot on.
    Here is a log.

    shiftsgood.hpl