87 GN doesn't shift into overdrive

[GNTurbo6]

I bought an 87 GN last Thursday and I was driving around today. I was going 65 on the high way and kept the throttle very steady. The engine was at about 3000 RPMs and it just wouldn't shift. Any ideas?

Mod list:
Delphi 37 lbs Fuel Injectors
Bosch 237 Fuel Pressure Regulator
160 Degree Thermostat
Walbro Fuel Pump
Turbo Tweak Computer chip (93 octane)
3" down pipe
Dual radiator fans

 

[SuperCPA]

If your SES light is not on, it sounds like you need to replace the lock-up solenoid in your transmission. This is not an uncommon problem when they get some age. Luckily, if that is the only problem, this task can be performed easily in your driveway.

 

[Black Car]

Are you talking about overdrive or lockup of the converter?

If it is lockup, get the car up to 60 mph and use your left foot and lift up the brake peddle. If the converter lock up, then you need to adjust the switch at the top of the brake peddle. If this doesn't work then it maybe the solenoid.

Gary

 

[GNTurbo6]

Does the fact that I don't have to press brake to shift out of park mean anything?

 

[are_one]

No, that is a feature on newer cars only.

 

[10-29GN]

I thought that I was having the same problem when I bought mine. The vdo aftermarket tach was reading around 3000 rpms at highway speed. I got a scan master and checked. It was the tach that was off and not the car. Try shifting into D while cruising and see if rpms go up. If so you were in overdrive.