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Old Jul 7, 2012 | 02:40 PM
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code p0308

I have a 2000 expedition with 223,000 miles. While towing a pair of jet-skis to the lake my check engine light began flashing and the truck began to run rough. After stopping, the check engine light came on and I pulled the code. It was p0308, cylinder #8 misfire. When the truck cooled, i replaced the #8 coil. The truck ran fine until towing the jet-skis home. The light began flashing again and misfiring. I checked the #8 plug and it was fuel fouled. I replaced all the spark plugs and checked the truck, still mis-firing and rough idle. Any ideas? burnt valve? What else should I check?
Any help would be appreciated.
 
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Old Jul 9, 2012 | 04:10 PM
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enriched&beyound
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From: NE Iowa JD Country
Originally Posted by felixbot
I have a 2000 expedition with 223,000 miles. While towing a pair of jet-skis to the lake my check engine light began flashing and the truck began to run rough. After stopping, the check engine light came on and I pulled the code. It was p0308, cylinder #8 misfire. When the truck cooled, i replaced the #8 coil. The truck ran fine until towing the jet-skis home. The light began flashing again and misfiring. I checked the #8 plug and it was fuel fouled. I replaced all the spark plugs and checked the truck, still mis-firing and rough idle. Any ideas? burnt valve? What else should I check?
Any help would be appreciated.
really doubt that there is anything too serious wrong.

has the codes been run/scanned again?

odds are the you have another COP (coil on plug) go bad, just on a different cylinder.

did you torque the new spark plugs to 28ft/lbs...did you use dielectric compound/grease on the COP boot?

did you change the fuel filter? air filter?

another recommendation is to clean the AIC and check for vacuum leaks....one known spot to check is the PCV line , elbow on the rear of the throttlebody housing. shucks could hurt to change the PCV valve too.
 
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Old Jul 11, 2012 | 05:18 AM
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Superb advice up there ^^^, couldn't have said it better myself!

I'd add check the COP connector from the wire harness too. I had one become intermittent after a plug change, the small locking tabs had broken off. An NAPA EC259 fixed this problem but other suppliers also sell pigtailed COP connectors too.
 
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