CEL on my 2002 5.4l F150

[KBScobravert]

Checked it and it is a P0304 and it is running like poop. Changed out the #4 coil pack to no avail. Checked the plug and it is in there still. When I pulled the coil pack the boot came off in the head and it looks all gummed up. Still, changed it out and it didn't change the way it is running or the CEL.

I hate to think injector or worse.

Ideas from the Ford techs here?

[RJDCobra]

Did you change the #4 spark plug to? Take it there was no coolant from the heaters hose dripping in #4 hole. Outside of that if it's firing correctly from the coil driver inside the PCM. It's probably injector or base engine problem.

[orphan Shelby]

Sounds like if boot stuck in head then plugs havent been changed for awhile. Swap plug to other cyl and see if it moves. Is there an orange ring on outer plug porcelain? Get rid of it then. and using dialectic grease will help w future plug replacement. Also look for ANY moisture in hole and boot.

Im confident you know what your doing,but make sure you not thinking cyl 4 in same spot as a GM. Guy brought truck by awhile back changing plug and coil in what was actually cyl 6. But thatz another reason why I tell em to change all the plugs. Theyve been the same distance.

[DFWtechie]

I had this on mine and it was the injector. they are not to bad to replace and are that pricey either.

[greenbullitt]

I've had broken valve springs on these too

[KBScobravert]

I am dropping it off in the morning. I sure hope to hell it isn't a valve spring. Truck only has 124,000 miles. It has always ran fine until my wife drove it home from work during the ice storm. Now I did start it yesterday and for a minute I would swear it had cleared up.


I know it sounds lazy of me to not want to pull the rail and put an injector in it. I just would rather work on the cobra at this point.

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[orphan Shelby]

Have you checked plug beyond looking at it while in the hole? How old are they

[KBScobravert]

Have you checked plug beyond looking at it while in the hole? How old are they

Plug is practically new. Maybe 3k miles. I didn't pull it when I did the coil but I did put the socket on it and it was still there and tight.

[orphan Shelby]

Would physically look at it and move it to other cyl and the boot in case it was damaged while removing from head. I have cracked porcelain on a new plug putting in the rear cyl using wrong extension and wobble. Luckily codes take you to correct cyl to check. Shoot some brake clean and blow out hole. Inj are also super easy to swap,even the hardest number four. Almost temptex to run out there and do it. Hate to see ya waste a day over couple dollar plug.

[Skidonenko]

Did you use a motorcraft coil? The gummed up end on the boot was the plug side? should have pulled plug to clean and inspect for cracks no matter how new.

[Skidonenko]

Would physically look at it and move it to other cyl and the boot in case it was damaged while removing from head. I have cracked porcelain on a new plug putting in the rear cyl using wrong extension and wobble.

Ding, after feeling the crack a few times the deep plug sockets were worth every penny.

[KBScobravert]

I swap the injector from number 1 number 4. Pulled the spark plug and cleaned out the spark plug hole with a rag on an extension. There is still a miss but I don't know if I moved it from number four to number one now.

I will run up to Autozone haven't read the code sometime after lunch.

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[orphan Shelby]

number 4 is on the passenger side and farthest cyl to the rear. its buried pretty far. Easiest way to it is by removing pcm. You may be changing number 3 unknowingly.

[KBScobravert]

number 4 is on the passenger side and farthest cyl to the rear. its buried pretty far. Easiest way to it is by removing pcm. You may be changing number 3 unknowingly.

Nope. Number 4 has been the one I am working on. Positive.

[KBScobravert]

Well, swapped the injectors from 1 to 4, etc and the missfire code is still on cylinder 4.

Going to drop it off tomorrow and put my mind to other things. I am sure if it is a broken valve spring, they will find a way to put it to me.