Auto Trans Shifting Problem

[jgarced]

Alright, I have a 91 240sx SE w/Auto Trans. It only shifts when it hits 6k RPM. (exactly 6k) This happens on every gear. I think I have only let it shift as far as 3rd gear, don't wanna mess up the engine. I have read all of the posts regarding transmission problems but don't see anything similar. Here is what I have tried.

OD light doesn't work so I can't check for codes.Checked it with a code reader, nothing.Changed the trans computer, still doing the same thing. (tested while on a lift, Speedo does not move. Can't recall if it worked before)Have not checked or replaced the TPS or the Speed Sensor. (Should I spend the money on them just for the hell of it?)

Any ideas? I am in Florida now and the car is still in Jersey waiting to get fixed. Already been 1 year. I want my car!!!! Somebody help a brother out

[Ni2s4s0aSnX]

Did you try adding or replacing the transmission fluid? The TPS wouldn't have anything to do with those problems so that is out of the question. And probably no the speed sensor either.

[jgarced]

The trans fluid is fine. I have read that the Throttle Position Sensor and the speed sensor can both have weird affects on the transmission shifting. The weird thing is it does shift, but only at 6k.