speedstreetz

ok i know this has been posted 1000 times before but I can seem to find a straight answer so i would like to explain my exact situation and get a little feedback. I have a 2005 f-150 fx4 with 90,000mi and I live in germany so I really need to make sure im replacing the correct parts as it can get pretty expensive doing stuff here. One day on the highway last week i went to pass a semi and I was doing about 85mph my truck of course downshifted and then the CEL started flashing, I could tell something wasnt right with the throttle so of course I let off and the light quit and everything seemed to be fine. got where I was going about an hour later then when i went to head home it happend again getting on the highway. this time the CEL stayed on and I quickly pluged in my SCT and got p0306 DTC code. after getting home i left the truck running and couldnt notice any missfire just the normal tick (annoying!!!). so I swaped the 5 & 6 coils and still have the same issue. at 3/4 or more throttle and about 3000rpm the CEL flashes. When it shifts to O/D i get a bad missfire but no CEL. the spark plugs were done by me about 3000mi ago and the COP boots look fine. I also cleaned out all the valleys where the COPS go, they are dry and free of dirt.

Right now im leaning towards an injector. but have no ability to test anything here and cant wait on test equipment to come in (unless anyone has a better idea?)

SO.... If it is an injector can I upgrade all of them to 39# injectors since I plan on throwing a whipple on it this comming tax season with no issues untill then?

thank you
speed

alsatropine

iTrader: (2)

Check the necks of your coils. They have a tendency to get hairline cracks and start to short. Also OEM connectors don't like aftermarket cops if you swapped over to non oem stuff.

speedstreetz

Right now I have OEM coils, I swaped 5 and 6 and still get the 6 miss fire. I already ordered granatelli 45,000v ones before I did any troubleshooting. so I assume the coild are good since the problem didnt follow. all the connectors are good.

FANGS99

Pull the spark plug after the engine has ran for a few min....... If the plug is wet then the injector is firing.

speedstreetz

im leaning more towards the injector being stuck open, wouldnt that cause the plug to still be wet?. I also read somewhere that you can ohm the injectors, is that true?

Not trying to comeback with everything your suggesting im just trying to put the 6000 ideas ive read on other threads into one spot.

techrep

iTrader: (1)

I would swap the plugs also...you do have dielectric grease on your COP's ??

FordSilly

I would look to a bad coil or plug not an injector

speedstreetz

Took it to the dealer today and made an appt to get the injectors checked out... If they are bad, free if they are good... €200 service fee. So I decided to dig deeper. Found 4 loose spark plugs. Truck runs like new again minus the leaking manifold. What causes the plugs to come loose? I installed them and they were all really tight when I did. I thought I had avoided this issue by getting an 05 with the higher thread count!

primalurges

These don't normally loosen up it's quite the opposite. If you applied anitseize it should have only been applied the part below the threads not on the threads. Also these plugs don't have a crush washer so after they are hand tight they need a eight or sixteenth (verify) turn to tighten.

lariat05.4

It actually does happen fairly often on the 3v 5.4. A dealer installed mine and about 6 months later I found out one of my plugs had backed out. Happened to my buddy with an 06 as well. He was looking for his misfire for a few months before he figured it out. Many others in this forum have had similar issues. Some develop a tick mistaken for phasers or valve noise and also a fuel smell which is all from the backed out plug.