So I'm having problems with my car shifting into 3rd gear (maybe 4th). I have an automatic and right now my top speed is 35 mph and the rpm's skyrocket the wholetime. I went to the salvage yard and bought a used tcu. After I replaced it my car still does the same thing. Does my computer need to be reset or is the tranny just bad?

 

more than likely the tranny is going to be bad, from what i know ecu's don't go bad all that often, and since you've replaced it already, the culprit will be something to do with you transmission.

 

I had the same problem, I believe it is corrosion somewhere on the tranny and that the tranny is going out.

 

do you have fluid in it?

 

Yea, it has fluid. I took the car to a tranny shop this morning and they did say I have an internal tranny problem. They're taking apart my tranny right now to see what exactly is wrong with it.