1995 Pontiac Grand Am car bucks, stall sometimes

Tiny
TOMFITZY
  • MEMBER
  • 1995 PONTIAC GRAND AM
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 150,000 MILES
Hi, my car bucks, especially at high speeds, now it stalls when I stop, but only once in a while. I replaced plugs, boots, fuel filter. I looked at the coil housing, saw no cracks, there are 2 large coils in there, can they be removed(very tight) Could they be the problem? It is not the transmission, because if I am parked, I rev the engine slightly, it is missing or something, it is very rough, like stepping on the gas, letting go, stepping on it, letting go- so on so on
Sunday, April 19th, 2009 AT 5:26 PM

3 Replies

Tiny
RASMATAZ
  • MECHANIC
  • 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
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Sunday, April 19th, 2009 AT 5:29 PM
Tiny
TOMFITZY
  • MEMBER
  • 7 POSTS
Is there a way to test the coils? Do they come out of the housing or do I have to get a whole new housing? Also, I've been putting feul injector cleaner I it, this has been going on for 6 months. Now, It is getting worse.
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Sunday, April 19th, 2009 AT 5:35 PM
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Disregard the coil/s at this time and check what I've suggested then report back.

Checking the coil/s is the same way for cylindrical type by measuring the resistances in the primary and secondary windings.
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Sunday, April 19th, 2009 AT 5:48 PM

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