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2005 Ford F-150 RPM/Throttle

Tiny
GAB33
  • MEMBER
  • 2005 FORD F-150
  • V8
  • 4WD
  • AUTOMATIC
  • 150,000 MILES
Noticed that RPM jumps up and down while driving. But will not do it while stoped or idling. Once u drive off it will start again and will not stop. Also noticed when u disengauge overdrive it will not do it but when u engauge overdrive it will start up again u can feel the engine rev up and down as ur driving along.
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Monday, August 10th, 2009 AT 9:10 PM

1 Reply

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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Tuesday, August 11th, 2009 AT 2:20 AM

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