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Thread: 8L90 TCC Apply Ramp Question

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    Tuning Addict WS6FirebirdTA00's Avatar
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    8L90 TCC Apply Ramp Question

    I am trying to solve an annoyance.

    When I am at high load and the TCC is unlocked then starts to ramp up pressure to lock it, it hits too hard. I would like to "ride it out" a little more before it locks.

    If I am at low load, it does it quite nicely. The RPM hold fairly flat and then once locked it will start to pick back up in RPM. Mainly in the 1200-1500 RPM range. Slip RPM here is about 200 and it is flat from 200 to 400, which is why I think it is related to the engine RPM and not slip.

    The high load areas have the annoying flare and quick jump back to low RPM. It just seems the ramp can't compensate for the quick flare, then over compensates. Seems to happen between 1500 and 2200 RPM - if my quick on the throttle response gets the RPM up that high.

    Looking at the TCC apply ramp table and the RPM this happens at, I was going to lower the apply ramp pressure at 2000 RPM. I think the 1500 RPM feels OK, so trying not to touch that too much. The left axis is showing "ramp rate" which has me questioning if that is truly a ramp rate or just the current RPM and picks up the pressure based on the slip RPM.

    My main reason for posting - am I understanding that table right? Stock file attached if needed.

    While on the topic, I also notice areas the TCC unlocks when all the speeds vs gears indicate it should be locked. It seems to be on downshifts and I can't pinpoint the conditions to catch it on a log. What else would cause the TCC to unlock? Is it simply due to the downshift?
    Attached Files Attached Files
    Sulski Performance Tuning
    2000 WS6 M6 - LS6 (long block, refreshed top end), 10.8:1 CR, 90 mm ported FAST, Exo-Skel, 227/232 cam, QTP HVMC, EWP, GMMG, 9" w/4.11s
    2018 Sierra SLT 5.3L A8 - Airaid intake tube, GM Borla catback, L86 Intake/Ported TB