Nissan Repair: 1992 nissan sentra xe, nissan sentra, torque converter

Question
i have a sentra xe and when i'm driving it , it won't go into overdrive until the engine gets hot, then it will pop in and out of it. what could be the problem

Answer
Mary,

The computer waits until the engine is warm before it allows the car to shift to forth gear and then allow the torque converter to lock.  You could have something as simple as the temperature sensor shorting.  This is the one the computer reads to allow the shift.  And, the fluid probably needs to be changed too.  If you are driving 37 to 40 miles an hour will also cause the transmission to hunt for a gear.  That is, shift from forth to third and back again.  If this is the case drive a little faster or slower.  Or, only for that brief driving area shift into third.