Running sluggish and not accelerating

Tiny
ASHLEYFROMNOLA
  • MEMBER
  • 2003 FORD EXPEDITION
  • V8
  • 2WD
  • AUTOMATIC
  • 121,000 MILES
I have replaced spark plugs, and brought to the shop several times. There were not any codes for a while to be pulled, but when it finally did, it showed misfire on cylinder five (which is one of the ones I replaced). We replaced the coil and plug but still runs terrible. I have no idea where to look next. My mechanic suggested it may be the catalytic converter, but he does not look into those types of issues. I do not want to spend another $100.00 just getting Ford to look at it. If you have any ideas what some possibilities could be, it would be greatly appreciated.
Wednesday, January 20th, 2010 AT 6:59 PM

1 Reply

Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Check and test the following below:

Oxygen sensor.
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.
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Wednesday, January 20th, 2010 AT 7:14 PM

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