Car: 2004 Pontiac Grand Prix GTP
Engine: 3.8L Supercharged
Mileage: 94,300 miles
Usually after driving the car for a long period of time (approx 20 miles or more), Ill begin to hear a grinding coming from the front of the car. The grinding/ groaning can be felt in the gas pedal aswell. Depending how hard I hit the gas the frequency increases. Im not sure if this is associated with the grinding, but i noticed that when I turn sharply and go easy on the gas and progressively add pressure the car will cut out until i cut straighten the wheel. Then all the power I requested is applied all at once.
What the locals think:
CV Shafts- Sears told me the first time i went to get them checked that my CV shaft boot was a little loose, suggested changing it. Then I went back two weeks later and they denied saying that and said my cv shafts were fine. (talk about confusing)
Wheel Bearings- Someone I know said my wheel bearing could be slipping or my traction control could be on its way out, so i replaced both front bearings.
Tune up- Someone suggested it could be mis-firing, with it coming up on 100,000 miles, i did a tune up. (plugs, wires, coil packs)
Transmission- Someone said the transmission could be going bad. So i did a flush and inspected the fluid, no shavings or any sign of extreme wear. (car shifts great too.)
Clogged Catalytic converter- the cat was clogged, two new 02 sensors and a new cat didn’t even help with the issue im describing, but it does have more power now (:
Throttle Body- Someone said it could be a dirty throttle body…so i had that cleaned also.
and finally, some electric temperature sensor- someone said it wasn’t getting the right fuel mixture, so i replaced the $30.00 sensor to remedy that.
Fuel pressure was also tested to ensure the fuel pump was doing its job, everything checked out great.*
My attempts have only costed me tons of money and no answers. Can someone please help me!?