Problem with brand new 4R70W.
Transmission is in a 95 Supercoupe. it has an Art Carr converter and the transmission was built and installed by Darrin.
On the drive home from Indiana the owner noticed that it shifted funky and converter lockup was goofy. It's been almost a year since the tranny was built and installed but the car has extremely few miles on it. Basically the guy drove it home to Chicago from Indiana and parked it. The customer can't really specify what the problems were anymore because it was almost a year ago, but he called Darrin and at the time he said the funky shifting was due to it needing the proper transmission tune.
Problems were dismissed and the car came to Ohio for engine work. I drove the car from Chicago to Ohio and noticed along the way the converter lock up was irratic and the car seemed to surge under WOT. Didn't worry about it too much because I figured it just needed a good chip and it would be fine.
When I got it here to Ohio we put it on the dyno to get a baseline pull before engine work began. On the dyno the converter was locking and unlocking irratically producing a very distorted graph. The motor was also running like crap so again, we didn't worry about it.
Now with a good motor in the car and a LOT of tuning and experimenting with various settings (from stock to SCT standard files to my own files, to other files by known tuners) and the thing is getting worse. In order to dyno tune the car we had to command the converter open because it won't stay locked up under load.
In fact, it will randomly unlock under cruise as well. I've datalogged the motor running along at 2000rpm and the converter will unlock for maybe .5 sec causing a little rpm spike and then it goes back to normal. Sometimes it will flare after a shift, sometimes it will do a little "shuffle" between gears where it locks /unlocks /locks again.
After the final tuning session for the motor, now it has started shuddering as you come to a complete stop, and will often shuddter as you begin to accelerate again from being stopped. Something is really wrong, but I dont' know enough about these trannies to even start guessing. The fluid is full just as Darrin filled it when he installed it.