1999 Pontiac Grand Am Engine Missfiring????

1999 PONTIAC GRAND AM
15,000 MILES • 6 CYL • FWD • AUTOMATIC
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AUTUMNSMOMMY
  • MEMBER
  • 1 POST
Hopefully you understand my problem. While I am driving, my car will run fine. More often now though, when I am driving and go to accelerate my car feels like it is missfiring. I think you would say missfiring. It feels like the front of my car is trying to tug me up the hill. Just recently, it got worse in that I could barely make it up the steep hills on the highway. My husband put a new fuel filter in and my car does run better. It doesn't tug near as much, but it still will do it when I am trying to accelerate going up a hill. The fuel filter he replaced was on the rear of the car. I wanted to know if there was another fuel filter on the front of the car or not? I was told some cars have that. If not that then what else could it be? I do need to replace the fuel pump, I know that. If you could help, that would be great.
Nov 28, 2009 at 11:22 PM
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RASMATAZ
  • CAR REPAIR CONTRIBUTOR
  • 75,992 POSTS
Dirty fuel injectors (cleaning the injectors often fixes this).
Bad MAP (manifold absolute pressure) sensor
Bad TPS (throttle position) sensor
Bad or dirty MAF (mass airflow) sensor
Low fuel pressure (leaky fuel pressure regulator or weak fuel pump)
Vacuum leaks (intake manifold, vacuum hoses, throttle body, EGR valve)
Bad gasoline (fuel contaminated with water or too much alcohol)

Sometimes, what feels like a hesitation is actually ignition misfire rather than lean misfire. The causes of ignition misfire may include:

Dirty or worn spark plugs
Bad plug wires
Weak ignition coil
Wet plug wires
Nov 29, 2009 at 3:40 AM
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