Hello everyone.

I bought a 95’ sc400 that seemed to be shifting a little high at times and rough at other times. I did everything in my power to find a fix to the shifting issues. I did shift solenoids, fluid flushes, and even sent for my ecu to be rebuilt and when it came back….nothing. Eventually I took it to a mechanic that recommend that I just replace the ECU. I bought a rebuilt ecu online and all my problems went away. The car shifted perfect….for all of 2 months. Then my issues slowly started coming back the way they were before. Any ideas????

 

Who rebuilt your original ECU, and who did you buy your rebuilt ECU from? Some rebuilders just replace leaky caps and clean the board up but don't bother to check for broken traces.
If it was shifting fine for a while after the rebuilt ECU was installed this tells me that the issue is not a mechanical problem in the transmission and is more than likely a computer problem.

 

Relentless motorsports out in Texas repaired it, but when it got to mine, absolutely nothing was different. When I got the rebuilt one from a repair shop out in cali, the car shifted smooth.

 

If I was in your shoes I'd crack open the ECU and take a look inside to see if anything is amiss. New leaks or incorrect/poor quality caps used. If all seems fine then I'd get to probing wires to make sure all the solenoids and sensors have proper resistance and power. If that's good then you may end up needing a transmission...