1988 Pontiac Firebird Hesitation

TOMVULLO

MEMBER
1988 PONTIAC FIREBIRD
V8
2WD
AUTOMATIC
49,000 MILES

I have a 1988 Firebird with 49K original miles. I only use it to drive around locally to warm it up. It drives fine for about the first 15 minutes, but then after it is warmed up I feel hesitation upon accelateration, an occasional backfire, and it recently stalled while waiting for a stop sign. I have no problems when I warm it up in park (auto transmission), even when I rev the 5.0 L V8 engine. I changed the fuel filter about two months ago and the wires and plugs checked out o.K. The car has the original catalytic convertor. Again, I only experience these problems after I drive it a while and it has warmed up. Any suggestions as to what is causing it? The cat converter?

Thanks in advance for your answers.

Tom

1 Reply

RASMATAZ

MECHANIC
75,992 POSTS

Check and test below could be one of the following that's causing it.

Oxygen sensor
Catalytic converter
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
Cap and Rotor