2000 Expedition Help

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Sep 13, 2008 | 11:49 AM

shanempickle

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2000 Expedition Help

Okay, I have a 2000 Expedition with a 5.4L. About 2 months ago the Service Engine light came on and the codes said it was missing on Cylinders 5, 6, & 7. So I replaced all the plugs (not bosch). Still missing on cylinder 6. Replaced coil on #6 and all coil boots (double work). Ran great for about 2000 mile trip. Turned a corner and hit a bump and all of a sudden it's running horrible again. Code says #6 is missing again. Tested input voltage to injector and injector resistance, both within specs.

Help..... could it be that the new coil is bad? Can anyone tell me how to test the input voltage to the coil and test the coil resistance? Any other thoughts and suggestions? No there isn't any moisture in the plug hole.

Thanks in advance.

Shane

Sep 13, 2008 | 12:50 PM

alloro

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From: 0,0,1

Swap the coil with the one next to it and see if the code moves to the next cylinder.

Sep 13, 2008 | 06:13 PM

cbradford

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From: Lost in Pa.

I have had new coils fail in a couple of months, so like alloro said swap with another and see if code changes to swaped cylinder

Sep 13, 2008 | 10:16 PM

vettman80

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From: Friend Nebraska

vettman80

just a thought did you use any dielectric grease on the new cop

Sep 13, 2008 | 10:29 PM

Ben Marshall

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From: New Mexico

Im not sure what kind of voltage you should have, but according to Haynes, to check primary resistance, take the coil off and put an ohmmeter across the two terminals on the plug end of the coil. It should be around .55 ohms. To check secondary resistance, Put one ohmmeter probe on one of the plug terminals, and the other on the secondary terminal (the spring part that goes on the spark plug) It should be around 5,500 ohms. If either of those are out of range, replace it

Sep 14, 2008 | 11:18 AM

cbradford

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From: Lost in Pa.

The insulation in the secondary could be breaking down under load to check this you would need a HIGH POT TESTER which uses high voltage to check insulation failure and not sure if they will even go to say 35,000 volts