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Thread: WOT Shift Speed vs Shift - Normal Table questions

  1. #1
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    Post WOT Shift Speed vs Shift - Normal Table questions

    Hello,

    I have two questions regarding the WOT Shift Speed vs Shift - Normal Table.
    Here are the parameters:

    2>1 | 19
    3>2 | 36
    4>3 | 59
    5>4 | 76
    6>5 | 107
    7>6 | 313
    8>7 | 313
    1>2 | 23
    2>3 | 42
    3>4 | 63
    4>5 | 81
    5>6 | 94
    6>7 | 313
    7>8 | 313

    Question 1:
    How is the transmission supposed to upshift 5>6 @94 MPH and downshift 6>5 @ 107 MPH ?
    Did the tuner make a mistake with this setting ?

    Question 2:
    With these settings, will the vehicle ever go to 7th or 8th speed at WOT ?

    Thank you!

  2. #2
    Advanced Tuner IARLLC's Avatar
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    1: Yes
    2: No

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    This modified tune is from a 2015.5 GM truck with the 6.2L (L86) engine and 8L90e transmission. 7th and 8th gear are disabled to make sure that the truck never goes above 143 MPH.

    However I still don't understand why they would program the 6>5 (112 MPH in stock tune) downshift at a higher speed than the 5>6 (99 MPH in stock tune) upshift. Can someone shed light on this?

  4. #4
    Advanced Tuner IARLLC's Avatar
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    Yep. Kinda weird. If you stay full throttle past your upshift in to 6th at 99 and keep climbing at full throttle you will get a downshift back to 5th at 112....locking you into a 5-6-5-6 cycle at full throttle I guess. The 2015.5 had a 135mph limit though....

  5. #5
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    Do you happen to know if there is a parameter that you set in VCM editor that doesn't allow the vehicle to go above a certain speed ? If so, could you please tell me where to find it ?

  6. #6
    Advanced Tuner IARLLC's Avatar
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    Under Speedo>Limiter>Limit by fuel the factory set 2015.5 L86 8L90E rigs to 135mph. But if you don't change the trans shift settings you will be stuck in the above mentioned 5>6>5>6 loop at 112 if you hold full throttle.

    If you want to increase the limiter above 135mph you need to also change Speedo>Limiter>General>Source from GMLAN to Calibration....and prepare for the driveline to come apart and abuse the bottom of your rig. If the driveline does not fly out a 2015.5 L86 Yukon Denali will push at least 135 with very mild tuning...not that I would know

  7. #7
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    Thank you for your feedback. I am actually going to limit the max speed to 110 MPH... I don't want the truck to go above that speed.
    I am also going to fix the 5>6>5>6 loop.
    Do you happen to have a factory tune for the 2016-2017 Cadillac Escalade or Yukon ? i am curious to see if the tune addressed this issue from the factory.
    Thank you!

  8. #8
    Advanced Tuner IARLLC's Avatar
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    I have loads of 15 6speeds, 15.5 8 speeds, and 17 8 speeds but, you can't actually read a 17 trans tune....After you have the TCM T87A unlocked and you plug in to read it (you have to be connected to the internet) you just get a standard GM stock trans tune from HPTuners via your internet connection.

    Maybe the repository has a 16 8 speed you can check out. I am getting curious what you will find.

  9. #9
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    Looks like the 17 8 speed has the same settings
    This is pretty strange. Do you think there is a method to the madness ?

  10. #10
    Advanced Tuner IARLLC's Avatar
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    Actually, now that I think about it...
    2017 L86 8L90E Yukon Denalis (with stock TCM calibration) were hitting a 116mph limiter (probably BCM) with no tuning. Switching the limiter source from GMLAN to Calibration allowed them to hit the factory PCM limit (135mph). I (or whoever was testing them never experienced the 5>6>5>6 loop that the 2015.5 shift tables seem to suggest.