307,000 miles
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Joined: Sep 2011
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From: Clitherall, MN.
307,000 miles
Howdy folks, my 98 F150, 5.4, good ole truck that it is, has an issue. For the last year or so I have had a P0301 pop up now and then. So I would pull the plug, clean it up, set the gap again. Put it back together and everything is fine for a while. Plug color is a light tan, swapped coils a few times which didn't seem to make a difference. The last time I pulled the plug the gap was at about 40. Seems something closed the gap after it was installed. The last time I did all this it lasted about 10 seconds then the miss came back. Pulled the plug again and it was like the plug was dropped and the gap was completely closed. So I bend it back out and reinstall. Runs fine for a while and misses again. I'm wondering if something could have fallen in the plug whole or if maybe carbon build up on op of the piston could cause this. I have since parked the truck and am driving a different one now. Not much fun working on it in MN this time of the year. Just wondering if you guys have any experience with this or any insight as to what might be going on. Thanks. Hope everyone had a Merry Christmas and will have a Happy New Year.
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Joined: Sep 2006
Posts: 7,907
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Use a bore scope and take a look.
Harbor Freight has them fairly cheap now.
If the truck is worth it, the investment is warranted.
The misfires just made carbon worse and may have a large carbon chip moving around in the cylinder.
The pistons have deep crowns per the cylinder head used to control the static compression ratio.
These engines in good shape and kept up should never accumulate that much carbon in the cylinders unless that cylinder has broken rings.
Good luck.
Harbor Freight has them fairly cheap now.
If the truck is worth it, the investment is warranted.
The misfires just made carbon worse and may have a large carbon chip moving around in the cylinder.
The pistons have deep crowns per the cylinder head used to control the static compression ratio.
These engines in good shape and kept up should never accumulate that much carbon in the cylinders unless that cylinder has broken rings.
Good luck.
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