1988 Ford Thunderbird Thunderbird V8 hesitation

P RINDGE

MEMBER
1988 FORD THUNDERBIRD
V8
2WD
AUTOMATIC
72,000 MILES

Just off idle there is a hesitation/stumble for my fuel injected 302 V8 1988 Thunderbird. Happens at speed when the accelerated is pressed a little "to maintain speed". You can feel the engine chug as you coast to a red light also. Occurs in ODrive, drive or neutral. Replaced the IAC, cleaned the throttle body, changed cap/rotor, and advanced the timing. Still have it. Other than plugs and wires engine is stock. Anything stronger than slight accelration she runs strong and smooth. Thanks for any help. Phil

Wednesday, November 18th, 2009 AT 12:43 PM

2 Replies

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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Wednesday, November 18th, 2009 AT 4:55 PM

P RINDGE

MEMBER
9 POSTS

Thanks rasmataz.
Went though and changed each spark plug and wire one at a time and ran it after each change (16x) - no change in the condition. Haven't located any vacumm leaks (yet) or the MAP sensor. Filled the gas tank and added STP a week before the post. (Same tank still). Due to low usage of the car I have only been putting in 12 gallons each time I refuel so that it doesn't get stale. I may go ahead and change the fuel filter due to the age of it. MY gut is pushing me to the TPS but don't know how to "set up" a new one. Phil

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Tuesday, November 24th, 2009 AT 11:45 AM