carp104

I am completely stumped here. I just bought a 2006 F150 with the 5.4l 3 valve triton engine about 5 months ago with 85K mi on it. Now at 90K the truck out of the blue starts to idle rough and shortly after the check engine light begins flashing. Pulled into Autozone and scanned P0300, P0301, P0305. Misfires cylinders 1 & 5.

Here is what I have checked so far:

-Spark Plugs (replaced)
-Coils (swapped, problem did not follow coil)
-Fuel Injectors (swapped, problem did not follow injector)
-Cam Sensor
-MAF Sensor
-Compression Check (engine has good compression)
-VCT Solenoids (replaced, problem seem to very slightly improved but still idling rough)

The misfire really is only noticeable at idle and as soon as you press the gas it's barely noticeable at all at higher rpms. There is also NO rattling or NO ticking or clicking noises during startup or any other time. This led me to believe it was the VCT solenoid instead of something like the cam phasers but apparently I was wrong. Could it be possible there are other error codes that haven't been thrown yet? Surely there has to be a little more than just two misfires - how do you work with such a vague code or am I not fully understanding them?

I'm about ready to throw in the white flag on this and take it in to the dealership - which I fear I will be told it's major $$$$. This seems to be a common problem with these trucks however every thread I find regarding this issue on any forum just dies dead in its track with no solution.

I guess my next step is to check the "real" oil pressure and see if there's any oil flow issues?

Has anyone solved this problem?

techrep

iTrader: (1)

what brand plugs did you install and did you do them all ??

carp104

Motorcraft & just the two misfiring cylinders for now.

techrep

iTrader: (1)

I would replace them all and clear the codes..

IceFishinFool

Unplug the vct solenoids and see if that does any thing for ya. If so then replace them.

lewissa81

I agree 100%.

carp104

I stated that I replaced these in my original post

connorfx4

I also agree that replacing all the plugs is a good idea. I never understood only changing a few. If you're already in there why not do them all?

IssacCheriyathu

It wouldn't hurt to check this: https://www.f150forum.com/f4/final-r...-sound-141266/

carp104

I'm still 100% stuck with this. I went ahead and changed ALL the spark plugs myself - which was a nightmare as 4 of the 8 broke off in the head. 3 came out with the Lisle tool and one broke off the Lisle tool. I had to modify the tool pieces on a lathe and was able to get the last one out.

Anyway, the truck now has all new plugs, put die-electric gel on all coils - started truck and misfire still there.

My next step is to check oil pressure to see if the cam phasers may be the problem. This is incredibly frustrating and I'm almost out of places to look.