I picked this truck up in Oct 99 it's a 2000 F150 4.6L 4X4 supercab flareside with 5-speed standard transmission. I have 55,000 miles on it. About 6 months ago it was misfiring going up grades. I took it to the dealer, who couldn't really find anything wrong with it--they replaced the fuel filter. Within 2 days, I had the same problem. As you can see, i don't drive this truck a lot--13 mpg. I drive it 1-way about 20 miles to work one day a week, the change in altitude 3200 to 4000 ft. Today the Check Engine light came on, and it started blinking while going up a steep grade, then went back to solid light. I've taken it in to the dealer for service every time it was called for. Any ideas what I can do? Thanks.

 

Pull the codes for free at auto parts places like autozone. Bring the codes back here. Sounds like a misfire. Probably coil related. Watch out for dealers as they will cost about 8-10 times more than what it would only cost you to pick the parts up and take 30 minutes to do. Need the codes though.

 

Found more info on misfiring problems. Went to O'Reilleys and used their meter to read the codes. It came up with #6 missing. It seems like, for an 8-cylinder, having just one spark plug misfiring it shouldn't run that rough. The guy at the counter said the 4.6 and 5.4 have had problems with spark plugs coming loose or blowing out of the heads, because they have a repair kit for the head threads... I did buy just one coil and a complete set of spark plugs, but looking at where some of the plugs are at, I suspect it's going to be fun to try to get to them. Does it seem like I'm on the right track? Thanks for your help.

 

take the coil back and order them off e-bay you can get a whole set of 8 for about $80. Use only motor craft plugs modulars are picky. torque the plugs to 28 lbs dry no anti-sieze. Lube the boots with dielectric grease to water proof them and your truck is good as new.

 

Before spending any more money disconnect the battery for a minute or so to reset the PCM. Swap the #6 coil with the #5. Drive till it misses again and get the codes read. Make sure you get the code number(s) not the description. Your #6 misfire would be a P0306. If the code changes to a P0305 then the coil is the culprit.

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