Auto trans won't shift

[The_Commodore]

I finally got my new engine running on my 91, but now the auto transmission does not want to shift on its own. I pulled the torque converter out with the old engine, but that and the input shaft on the trans did not appear to be damaged, and everything went back together fine. The check engine light is on, turns off when you change between park, reverse, and drive, but turns back on after a minute. Im afraid I may have internally damaged the torque converter, but I can shift between 1st and 2nd manually on the column shifter. Thats the only way I can get it to shift gears in drive, I cant get it to shift automatically. Is it the torque converter, or hopefully something easier and less expensive to repair?

 

[IZwack]

Maybe you forgot to reconnect a sensor on the transmission -- the transmission's RPMs must be known in order for the computer to shift.

 

[Willard]

His is a '91, no sensors. Torque converter is probably fine given that it moves. Something internal to the transmission isn't right.

 

[The_Commodore]

I got it to shift this morning, but at about 50 mph around 5000 rpm. Maybe a bad electrical connection or something? Or the computer needs replaced?

 

[BrooklynBay]

The only electrical components on the A4LD of this year are the TCC solenoid, 3-4 shift solenoid, VSS, and the neutral safety switch. Only overdrive (4th gear) is controlled electronically. The TCC solenoid engages the torque converter. 5K RPMs is way too much slippage. Did you adjust your bands, modulator, and kick down cable? You should find out what code is causing a check engine light to appear.