2003 Ford F-150 engine misfire

CHANCES50

MEMBER
2003 FORD F-150
V8
4WD
AUTOMATIC
162,000 MILES

2003 Ford F150 5.4 v8 I've been having an issue with the spark plugs for some time now about every 2 months the truck starts to miss really bad, Ill put a Scanner on it and it will tell me what cllinder I replace the plug and go on. The first time this happened I replaced all the plugs with the factory motorcraft plugs then in about 2 months it started to miss again, so I checked the code and replaced the Coil and sparkplug for that clyinder since then every couple months I have to replace a plug. Im lost on what could be causing this. All the plugs are clean as they were the day I put them in, when I pull them they look to be spot on not lean, rich or oily. Thanks Chance

Tuesday, January 12th, 2010 AT 9:26 PM

2 Replies

RASMATAZ

MECHANIC
75,992 POSTS

Engine misfiring can be caused by worn or fouled spark plugs, a weak spark (weak coil, bad spark plug wire), loss of compression, vacuum leaks, anything that causes an unusually lean fuel mixture (lean misfire), an EGR valve that is stuck open, dirty fuel injectors, low fuel pressure, or even bad fuel

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Tuesday, January 12th, 2010 AT 9:33 PM

CHANCES50

MEMBER
1 POST

Thanks but its not consistant with any clyinder and I replace the plug with a new one everytime it fix's the problem for about 2 months then it another plug needin to bereplaced.

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Tuesday, January 12th, 2010 AT 9:48 PM