JCT1990

I have an 06 with the 5.4L.. about 2 months ago I had a misfire in cylinder 8.. Replaced the coil, no more misfire. About 3 weeks later I get a misfire again in the same cylinder... Replaced the plug (that was fun).. no more misfire.. Today on my way into work I get another misfire this time in cylinder 4. Haven't had a chance to look at it yet but I'm just curious if this is a common thing or if I'm just having bad luck lol.

JCT1990

Alright... so first I go to check the coil, I remove the coil from cylinder 4 and replace it with cylinder 2... hook everything back up.. now I have 2 misfirers, cylinder 4 and cylinder 8.. I'm guessing the plug/injector is bad in cylinder 4?... But I dont get why im suddenly getting a misfire in 8 now. Any input is helpful at this point..

techrep

iTrader: (1)

How many mile's on your truck ?? Sounds like you need a complete tune-up...but you can try replacing #4 plug and COP...sound's like its time to do them all. don't forget to clear code's after replacing.

JCT1990

Its got 81k.. I kinda figured its time to change out the plugs, but I should do all the coil packs as well?

techrep

iTrader: (1)

when it's that time for me ...I plan to...81K you should be good for another 15K...COP's are known to fail with this motor...it's hit or miss.

JCT1990

Alright thanks, not what I planned on doing for new years eve but I need my truck lol.

redblaze71

Could be injector problems. I had an 05 that had all the injectors replaced by 25000 miles and Ford extended the warranty up to 120000. They would periodically stick open causing the problem. Eventually, they would all stay open. Had to drive it 65 miles once with two open, fuel mileage sucked. At about 32000, the cats had to be replaced because of all the raw fuel that built up in them. That was my worst experience with a Ford.

redblaze71

Oh and to add to the last post. About the plug replacement. I talked to a Ford mechanic when I traded off the '05. He told me then that the three valve 5.4 will have problems at plug change time. You are better changing them early than waiting til past 100k. The valve design leads to carbon build up around the plug at later miles and can potentially ruin the head while removing. Obviously this would be an expensive fix.

transmaster

Be sure to check the ECM. There is a problem with the ECM leaving coil pack powered up too long or all of the time burning them up even to the point of melting them.

JCT1990

Yeah when I took the plug out of cylinder 4, which was starting to seize up like you just said... I decided to just change them all. But I still haven't been able to fix the problem, so I dropped the truck off to a Ford mechanic today so we'll see what happens.