Can't figure it out!!!

[GTP Dad]

I have a 97 GTP. Lately when you are traveling on the flat the car runs great. When you go up a hill with the RPM's between 15 and 1800 the car bucks slightly. If you keep it above 2k rpm's then it runs fine or if you lift your foot and hit the gas again it quits doing it as long as the RPM's are above 2k.

There are no codes in the computer, the fuel filter is new, plugs and wires are less than 5k old. Haven't been able to check fuel pressure due to the weather and it is hard to do while driving. I have a couple of ideas: TPS, Fuel Pump or Fuel Pump Resistor.

Just trying to see what you all think it may be. Thanks in advance!!!!!

[Ripn12s]

Sounds like your torque convertor. When going up hill and at that low rpm it is having trouble deciding if it needs to be locked or not.

[BostonGuy - 001]

I agree....the fuel system (pump) operates the same regardless of going uphill or not. This sounds like a tranny problem/

[troy1]

sound like your engine is missing gets worse under a load alot of times if you TC is unlocking your tach will move 300 rpm but you should not feel it cuz it is PWM valve. do you have a 4T60E or 4T65E trans?

[99 Grand Prix GT]

I would haft to say your torque convertor (LOCK UP) is this problem , because mine did the same thing. I took my car to out local dealer ship and they deleted the Shift points out of the PCM, so that the car would relearn its shift points and it helped. It still might do it a little sometimes but not near as bad... At first the dealer ship told me that i might have a seal in the tranny that was bypassing the pressure and fluid. but we ruled out that problem becuase you could tap the brake and it would come right out of the lock up.. good luck

[GTP Dad]

Thanks for the information guys. The transmission was totally rebuilt about 3000 miles ago (4T65E) and the torque convertor was replaced at that time with a new one. Cost $2400 to rebuild. Luckily it is under warranty for 36K so I will get in touch with AAMCO since they did the work for me.

[drjimmy]

I'm having the same problem. The torque converter is the symptom but I'm not sure thats the problem. Thats the problem with drive be wire. Hard to figure out where to start looking. I also figure its the tps sensor. Just need to take the time to check it.