99 Pontiac Grand Prix GT mechanical problems?

Question

Car dies when accelerating and then revs up. From a dead stop I push the gas and the car jerks forward the rpms drop then it jumps up and goes. Took it to the mechanic he charged me $550 bucks changed the crankshaft sensor and ingintion module and that didn't fix it. It seems to only have this problem when it warm. It usually only jerks and drives rough at low speeds (45mph or less). Any ideas would be great

This is a 3.8 V6, I replace the plugs and wires a few weeks ago so I know that isn't the problem

Answer 1

i had the same problem in my 99 grand prix gt 3.8 it was the mass air flow sensor.the part is very pricey but you should check it and make sure there is no dust or bug guts in it.you could clean it out but be very careful even a speck of dust can cause your car to "buck" when driving.follow your air filter back towards your engine its a flat black box with security screws. one minute to take out.even the engine light being on used to drive me nuts until i fixed it!!!! it only used to do it after the car warmred up and then the rpms would jump around.i thought it was the transmision at first.

Answer 2

Is this a 3.1 or a 3.4L motor? I assume the mechanic scanned the PCM and didn't find any codes?? Anyways, I would have a close look at all the spark plug wire ends on both ends and the condition of the ceramic portion of the spark plugs which had a tendency to corrode and/or carbon track which would give a misfire at times. You could also have a coil that is shorting out when it gets hot. When the motor is accelerated, it needs a hotter spark to jump the gaps so if the coil has a short to ground near the end of its path, you only get a portion of the available spark. The best thing to do is to check things when it is acting up.

Answer 3

I replaced several blower motor resistors on my GTP see if there is power on the blower motor wire and ground the other wire the fan should take off. If not it is the blower not the resistor. I am one of the founding menbers of club GP we're a great bunch and full of good ideas. Ground the motor that simulates the resistor being in there and if the blower does not run you found a worn out blower motor. If there is no power on the hot side of the blower there is another problem. Let us know.

Answer 4

Try replacing the fuel pressure regulator. There is a TSB regarding it, and go to the dealer to purchase a new one, as there is an updated version available.

Answer 5

egr valve. eguast/gas regulator valve. Had to have mine replaced in a 2002 Grand Am SE. I also had to have a new catalytic converter because I waited too long to fix it.