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1997 - 2003 Ford F150 General discussion on the Ford 1997 - 2003 F150 truck.

Cyl 5 misfire

 
Old 03-12-2019, 07:07 PM
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Default Cyl 5 misfire

Hi all, looking for some advice-
1999 F150 5.4 auto w/ 2wheel drive 145k mileage
Replaced plugs at 80k, all new COPs, 5k oil changes
Trucks running fine and get the call form my oldest that there's a "shudder" and the CEL's on. Get it home and I throw the reader on it, both banks running rich and cyl 5 misfire.
I flipped the cyl 6 COP and injector, no change. For giggles, replaced all of the injectors (had a bunch from another build), and the cyl 5 COP and spark plug. No change. Replaced the COP, injector and plug again, no change. I'm thinking it may be electrical at this point (COP or injector plug), but I was hoping (praying) someone may be able to pull something else out from experience as I really don't want to go thru cutting and pasting plugs.

Appreciate anything you guys and gals can come up with!

Frank

I
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Old 03-12-2019, 08:59 PM
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Has the cylinder got good compression?
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Old 03-12-2019, 10:18 PM
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JCR-
I didn't want to go there yet... You saw the Praying part, right?
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Old 03-12-2019, 10:48 PM
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Get a noid light and check signal to the harnesses for the injector and the coil.... otherwise, JCR has it.
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Old 03-12-2019, 11:06 PM
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Thanks guys-
Noid light ordered, compression test tomorrow-
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Old 03-13-2019, 12:03 PM
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I hope yours is electrical. The original motor in my ''03 with 160K on it had a misfire on #5 that persisted even after milling and inspecting the heads, and replacing the head gaskets. It turned out to be a hairline crack in the cylinder. Fortunately for me, the remanned motor was on the dealer's dime. Not trying to jinx you, just reporting.
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