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Thread: P59 Trans Torque Management Issues

  1. #1
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    P59 Trans Torque Management Issues

    I'm having a quirk/issue with trans torque management on the P59 controller in my 2006 Silverado. The calibration/OS is 12619623. The issue I have is that if I run some torque management to try and help the trans shift quick and safe, the torque reduction lasts too long at part throttle. It is highly unlike Gen 4 stuff where the timing pull is near instant and is put back near instant. In my case, when the PCM commanded the shift, the timing did pull near instantly just before the shift, however it took 1-2 seconds after shift completion for the timing to come back in. It wasnt a slow ramp in, it comes back all at once, it just took too long to come back in. It literally feels like a 50 shot of nitrous coming on a second or two after the shift. And while it?s under tm, the exhaust note is burble/misfire obviously from the retarded timing. At wot the timing pull is out and back in instantly. Like it should be! Matter of fact, my scanner didn?t even pick the timing drop up, but it?s undoubtedly there. I'm not seeing any table in my tune to shorten the length of torque reduction on the shifts. I'm attaching a copy of my tune with all of the torque management, shift time and pressure tables set back to stock. I'm open to any suggestions and help. Perhaps my OS is missing a table?

    my 2006 silver truck.hpt
    Last edited by SilverBullet6.0; 1 Week Ago at 01:08 AM.

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    I will post a log tonight, but essentially under part throttle shifts, the timing curve looks like ---\___/--- and while the timing is down, the engine obviously runs poor, then returns to normal. Im looking to make the TM timing cut look more like a gen 4 strategy whereas the timing curve would look like ----\/----

    I should add also, right now, my trans shift pressure and timing tables are all stock as it is a built trans with valve body and pump modifications to improve shift feel/timing. But i did try manipulating the shift time table in the tune to see if that was somehow calculating into the length of time timing is pulled and it had no effect.
    Last edited by SilverBullet6.0; 1 Week Ago at 11:31 AM.

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    I believe it to be the PCM being confused on part throttle shifts, as it has a high stall torque converter and rpm barely drops on part throttle shifts, making the PCM think the shift has not yet completed.

  4. #4
    My comment is more for conversation then it is a solution and is technically from a Gen 4('06 GTO). Is your RPM hitting or getting close to any RPM limits/cutoffs during the shifts? I have noticed when an RPM limit/cutoff was hit the PCM would go through its normal RPM limiting routine and then still apply TM after the RPM fell below the set threshold. The effect made for a sort of double-tapped(not exactly bouncing on the limiter) 1-2 shift and similar but long'ish 2-3 shift. The long'ish 2-3 shift was more of a slipping problem for me I believe. You may need to lower the shift RPM/Speed and/or raise any RPM limiters/cutoffs so the shift can operate freely within a larger "zone" of sorts.

    A theme seems to involve aftermarket stall convertors with longer shifts. Perhaps because the RPM fall during a shift is less than with stock convertors and the computer is not happy about it.

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    Nah, I'm 300-400rpm away from my limiter at wot, and my biggest issue is at part throttle. I do believe the low rpm drop of a high stall converter is the cause. The pcm is thinking the shift is slipping and therefore maintaining the torque reduction.

    I did notice a pattern of making it occur tonight. If I got wot from a dig/low in first gear, it shifts perfect through the 1-2 and the 2-3 with a near instant chirp of torque reduction on the shift. However, if i am already in 2nd, 3rd or 4th and kick it down, even if it shifts all the way to first, it will bog like hell on the next consequential 2-3 shift.

  6. #6
    Senior Tuner kingtal0n's Avatar
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    I've also seen some funny behaviors, there is another thread with similar diagnosis (converter stall to blame)
    My own car has a similar issue with 3-4 shifts, using 2800rpm 9.5" Yank converter (which is their lowest stall available). I guess the RPM drop just isn't good enough so the computer will maintain 'high' shift pressure (low current to EPC) and long torque management, and over-estimates the 'time of latest shift' will show 1.8seconds instead of the 0.25 seconds that it really took for 3-4. I think 'time of latest shift' is the clue.

    So far I don't see any way to fix it besides turn off the torque management for those part throttle situations. Luckily I don't care about TqMgMnt in 3-4 shifts because they aren't harsh or anything, and at WOT there is no issue for 135mph+ going into 4th gear (overdrive ugh)
    Last edited by kingtal0n; 5 Days Ago at 03:37 AM.

  7. #7
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    Quote Originally Posted by SilverBullet6.0 View Post
    I'm having a quirk/issue with trans torque management on the P59 controller in my 2006 Silverado. The calibration/OS is 12619623. The issue I have is that if I run some torque management to try and help the trans shift quick and safe, the torque reduction lasts too long at part throttle. It is highly unlike Gen 4 stuff where the timing pull is near instant and is put back near instant. In my case, when the PCM commanded the shift, the timing did pull near instantly just before the shift, however it took 1-2 seconds after shift completion for the timing to come back in. It wasnt a slow ramp in, it comes back all at once, it just took too long to come back in. It literally feels like a 50 shot of nitrous coming on a second or two after the shift. And while it?s under tm, the exhaust note is burble/misfire obviously from the retarded timing. At wot the timing pull is out and back in instantly. Like it should be! Matter of fact, my scanner didn?t even pick the timing drop up, but it?s undoubtedly there. I'm not seeing any table in my tune to shorten the length of torque reduction on the shifts. I'm attaching a copy of my tune with all of the torque management, shift time and pressure tables set back to stock. I'm open to any suggestions and help. Perhaps my OS is missing a table?

    my 2006 silver truck.hpt
    This should be a easy fix. Check "shift timing" tables. A value of 0.0-0.2 will work well.
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    Do you know if it's using 'Performance' mode all the time/as default? I'm doing a compare here with another stock 2006 VIN 'Z', and it's got the same all-zeros here, so I'm not saying you did anything wrong. But if you don't know which mode it uses I'd try copying the Performance TQ reduction over to Normal and see what happens.

    screenshot.17-05-2022 09.10.36.png

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    I have the ?tow/haul? switch wired to a push button on my ratchet shifter. I use both normal and performance modes. I?ve tried it about every which way I can. Only way to eliminate the issue is to eliminate tm all together and I don?t want to do that.

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    When I posted that file, I put all tm settings back to stock for a start point of any advice received here. Currently, I have those tables set to start reducing torque at 360 ft lbs and maintain 360ft lbs

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    Just for reference, I was at a buddy?s house tonight. He has an 07 model classic truck that?s flex fuel. His calibration/OS is different than mine. However, we both have cam/headers 5.3?s with 4L60E transmissions. We tried all my settings in his truck, and it all worked as should. Quick, crisp timing reduction on the shifts, no matter the load or throttle position. Only difference, he still has a stock torque converter, whereas I have a billet 258mm that stalls around 3000.

  12. #12
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    For a long time I Questioned how the OEM Ecu knows when the shift is completed. There is no way for it to tell from the transmission communication effort. Therefore it must be an algorithm based on some difference the transmission makes after a shift is completed. Exactly as you are suggesting, I think its correct. Shift timing I am pretty sure is only for adaption methods, it checks shift time and then adds pressure if the shift is slow and visca versa. I've turned my adapts off and tried all different numbers in shift time tables with no effect or change which more or less confirms it is powerless to influence. And when we break down how the transmission works internally- the only thing that really happens is pressure and volume fills a drum to bring a gear on. Solenoids to shift gears are either "ON" or "OFF" there is no PWM control over solenoids for shifting. Therefore following all of this reasoning the only shift timing control the ECU really has is shift pressure via EPC which we can clearly identify using Force motor current.

    The only other thing I Can think of besides those things I Listed alrdy (dont forget tune file or OS corruption) is if you could somehow change the slip or gear ratio qualification in the ECU. Like maybe there is a window we can't see that identifies slip or gear ratio for the transmission.

    Another thought, The RPM Drop prediction algorithm clearly seems to work backwards from gear ratio and vehicle speed- meaning if you adjusted the gear ratio wizard (,tire size) VSS to read higher or lower (like VSS = 20mph when you are really going 50mph) then the resulting RPM Drop will look much larger to the ECU because its expecting a much smaller drop between gear changes due to the wrong gearing input. You would lose anything the VSS controls but it could correct this issue. I havent given it much thought about the consequences but just giving you some ideas.

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    I?ve considered manipulating the gear ratios in the transmission general tab, to something closer ratio to mimic the minimal rpm drop on shift. I?m just not sure what the consequences of that would be. What else it might screw up. At minimum, I foresee it causing slip codes at cruise because the rpm?s different than expected

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    I?ve considered manipulating the gear ratios in the transmission general tab, to something closer ratio to mimic the minimal rpm drop on shift. I?m just not sure what the consequences of that would be. What else it might screw up. At minimum, I foresee it causing slip codes at cruise because the rpm?s different than expected

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    Have you tried reducing the shift timing I mentioned before?
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  16. #16
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    Screenshot (26).png
    Same issue. 2002 Silverado OS. P01 Ecm

  17. #17
    Some links to GM patents related to torque management. No idea if these were ever used in production vehicles.
    Control method for managing engine torque
    Shift torque management

    Also, check the XDFs posted here for things that might be related to the issue. I know you are using a different OS but there are some parameters in these XDFs that are usually not defined in HPT.
    Mother of all 7603 XDF files
    OS 12587604 P59 XDF file

  18. #18
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    Yes, I?ve tried stock, 0.200 and 0.000