I have a 2005 ctsv with an 8l90 swapped in using a tcm 2650 with 3.73 rear gears. For the most part the car has been doing great and has been issue free, but i do have a reoccurring issue I can't solve.
I can be cruising the car normally and will give it 30-70% throttle and it will kick down a few gears like it should. If i have to let off the throttle soon after the downshift finishes sometimes the car will fall into a neutral condition and free rev. This can sometimes be predictable or sometimes it isn't and when i go to accelerate it will rev up and act like it is slipping a clutch into gear and then grab. It will really slip and know its not good for this style of transmission. I am on the fence on whether this is a mechanical issue or an issue with the tcm 2650 and the swap part.
In the log the condition occurs at 2 minutes 10 seconds in, you can see where i give it throttle and rpm increases but speed does not. Its also says trans slip rpm is 2400 and its showing the tcm is a little confused on what gear it needs to jump to.
If anyone has dealt with this i could really use some advice before i swap completely over to gen 5 setup