1999 Ford F-150 please help

Tiny
BWONDER68
  • 1999 FORD F-150
  • 164,000 MILES

I have a Ford f150 5.4 liter and the check engine light came on. It runs horrible and idles rough. Diagnostic done and it said it was possible that it was a ma's fire on cylinder 3, or insufficient air flow. Replaced injector and coil pack. Replaced o2 sensors. What could be wrong?

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Thursday, October 17th, 2013 AT 6:11 PM

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Tiny
ASEMASTER6371
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Start with a compression tes. Did you change the plugs?

Roy

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Thursday, October 17th, 2013 AT 6:14 PM
Tiny
BWONDER68
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Didn't change plugs but compression test was done and compression is good

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Thursday, October 17th, 2013 AT 6:17 PM
Tiny
ASEMASTER6371
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I would replace the plugs before replacing any coils or injectors.

What was the compression?

Roy

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Thursday, October 17th, 2013 AT 6:22 PM
Tiny
BWONDER68
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I don't remember the number but it was fine. Why change the plugs first?

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Thursday, October 17th, 2013 AT 7:07 PM
Tiny
MADMIKE1735
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What were the codes retrieved? A cyl 3 misfire would set a p0303. Insufficient air flow is a whole different issue. If u already replaced the coil, and verified compression is good, then try swapping the spark plug to another cylinder, clear the code, and see if the misfire moves to that cylinder. Process of elimination.

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Saturday, October 19th, 2013 AT 9:21 PM

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