[SEPA]

2016 ss a8. Transmission does not lock up completely when cold in 5th and 6th gear only. Car is garage kept. Garage temp may be 40-45 deg depending on outside temp car does not get driven below 40deg. Lets say I am at 2000rpm in 5th gear with the engine coming up to temperature, if I go WOT the engine rpm will immediately go to about 3500rpm and while accelerating the car, it is not a complete slip, the car feels like it is accelerating from 2-3.5k rpm. Once the car engine is at running temperature, the problem goes away and the converter/trans will lock up completely fine in those gears. 1-4, 7 and 8 do not have this behavior.
Car had 2 fluid replacements for the shudder. 1st one at about 10k miles, 2nd at 11k miles. No issues until now. I've owned the car since 2018. 20k miles

Any idea on the issue?

[arpad_m]

I don't know the exact cause, but zeroing out the slip tables and increasing line pressures somewhat in the tune would probably fix it. Up to you whether you want to experiment with the trans tune, though; I understand that you may not feel 100% safe without a 100% accurate diagnosis.

[SEPA]

Originally Posted by arpad_m

I don't know the exact cause, but zeroing out the slip tables and increasing line pressures somewhat in the tune would probably fix it. Up to you whether you want to experiment with the trans tune, though; I understand that you may not feel 100% safe without a 100% accurate diagnosis.

Thanks for the response. The car is virtually stock. I was thinking maybe the individual gear clutches could be the issue. I searched this site and the WWW and could not find any reported issues similar to mine.

[ctrlz]

I am not sure what tool this is, but I think this kind of analysis is what you need: