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Thread: 8L90 shift points issue

  1. #1

    8L90 shift points issue

    Been having issues with a '18 SS with the A8 transmission. I did a whole cam kit, dod delete, nw 102 throttle body and other supporting mods and I can't get this thing to shift properly. Predicted Torque Source goes to "RPM Limit" and it shuts the throttle before shifting and it completely kills the car. Spark and fuel aren't being cut only throttle closes down to around 42%. Torque tables are calibrated, driver demand as well, predicted axle command is higher than actual, predicted torque is higher than actual, messed with shift mph using the bluecat tool and nothing. Still getting that "RPM limit" under predicted torque source and throttle closure

  2. #2
    Senior Tuner Ben Charles's Avatar
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    You know the rules to fight club.. post the tune

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  3. #3
    set shift points to stock, around 6400 and its shifting fine now. weird but i guess i'll just leave it like that. tthanks
    Last edited by luisdavid11; 10-23-2020 at 10:32 PM.

  4. #4
    zero the accel threshold rpm limit table. there is also a setting to "use predicted torque" that is enabled from the factory and i believe that is what your issue is. its not shift points.

  5. #5
    that is assuming you have raised your rev limiter correctly

  6. #6
    If the above does not work try upping your VTT up by about 10% in the rigger rpm range and see if it fixes it. Tjds post should fix it though but if not try the VTT.

  7. #7
    Quote Originally Posted by tjd1991 View Post
    zero the accel threshold rpm limit table. there is also a setting to "use predicted torque" that is enabled from the factory and i believe that is what your issue is. its not shift points.

    are you talking about ECM 12067? what does zeroing that table do?

  8. #8
    Yes. That makes it not freak out so to say when ramping up the rpms real fast.

  9. #9
    yeah i had all that done. accel threshold at 0 and use predicted torque at disabled. car would still close throttle real ugly before shifts no matter what i set the shift mph to. have to command super early shifts to get an ok shift. very weird

  10. #10
    Advanced Tuner
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    What about Fuel> Cuffof,DFCO>Startup Modifiers>Cold Engine

    Make sure the last column is higher RPM that what your trying to shift at. I had this problem on my L86 6l80e. The last column is the limit from 80 seconds on or something like that.

  11. #11
    yeah all of theh rpm limiters were set stupid high to rule them out and car still closed throttle before shifts and it would say "RPM Limit" under predicted source