u/Beneficial-Push2528

My new VR30 transmission had bucking issues from a standstill when it first got put in, so installer added about 2 quarts of fluid. No more bucking, but was still having rough shifts and flares occasionally in lower gears. It would also heat up to mid 230’s when pushed.

I jacked the car up, let it warm to about 100 degrees after shifting through gears slowly, popped the fill plug while running, and let about a quart of ATF pour out to my surprise... Put fill plug back in before fully drained because I was concerned after a whole quart came out.

Took it back on the highway and car shifted PERFECTLY, but still was getting way too hot after being pushed, hitting about 230. Attributed overheating to still being overfilled.

Did proper check procedure this time and another .5-.75 quarts came about before it slowed to a drip. Took it out on for a drive again, and the car is back to slipping VIOLENTLY when accelerating hard from a standstill, bucking extremely hard after rpm’s shoot up. On highway, acceleration is fine and shifting seems normal.

Any clues why trans has to be overfilled to function properly? Am so frustrated and stumped right now..

Could this theoretically be BCM related? Dealership refused to diag since I am VR30 swapped.

Codes appear related to different modules/systems— specifically U1000.

All fuses are good, grounds have been checked. I did notice the ECU Ident for the VR30 TCM is different than the ECU ident for the car. Could this be a factor?

Drives fine, but almost feels like high line pressure.

I am replacing struts with KYB’s and noticed they are much shorter than OEM when under no tension and only expand by about a centimeter or two once the spring is on and they are under tension. It almost seems like they are about to explode there’s so much tension compared to OEM, is this normal and will they settle once on the car?