I have 2005 F-150 FX4 with 87,000mi 5.4L 3v

Problem: Code p0316 keeps coming on my edge no check engine light.
The truck seems to idle kinda rough at start up it clears up after warming up. Truck runs fine after warming up has plenty of power and pull fine with no signs of a miss.

What I have done: I have replace all spark plugs, swap Inj and COP with #5. Fueled with fuel injector cleaner. Replace plug one more time. Compression test was perfect. Also check for any loose wire or connection. After a few day the rough idle came back at start up.

Im all out of ideas, only thing I can think is that the fuel injector port on the intake manifold is clogged or maybe the ECM. Any suggestion? Thanks for any help.

 

I would get it to the dealer as soon as possible, and have the injector checked. Sounds as if it is leaking and is flooded on start up. If so, you are at risk of hydrolocking the engine. Ford has an extended warranty on the injectors for the 2005s.

 

Thanks bluejay for the quick reply!, I already swap injectors with cyl # 5 and no change in code still P0306 cyl # 6.

 

If you have done all of that, I would begin to suspect the one ( okay, two, lol) common denominator left - the injector or COP driver for Cyl # 6 in the PCM, or a related harness issue for same.

A capable dealer should be able to diagnose this.

Good luck.

MGD

 

I will go over the harness one more time, how do I verify if the COP driver is bad? scan tool right

 

Update the code was gone for a while is back on. Im afraid it will be a big wste of time and money take it to a dealer. any suggerstions? thanks

 

The coil is bad. You already verified lol.

 

Another thought is a bad lash adjuster that is leaking down and is slow to regain its pump. An exhaust follower off could also casue this problem and yes you will still get good compression with both of these conditions.

 

Right, so, you might wanna swap coils next to determine. I bet it's a coil tho.

 

Thanks for replies! I already swap coils between 5 and 6 no change but I think I might replace all 8 coils. I heard of one coil being bad and actually might cause other coils to act up. The truck run fine but stumbles a bit when cold goes away when warm.

 

6 and 5 are back to back in firing order. Try swapping with #1. It shouldn't matter, but I might, - before removing the cam cover anyway. Also, a bad fuel filter can pick on a particular cylinder.

 

Thanks, I replaced the fuel filter twice. Swapped injectors and compression test nothing. Dont understand y it idle a bit rough could and it goes away when warms. has plenty of power and being getting grea mpg city 13.6

 

Agreed.

 

HOw long can I run it with bad lash adjuster or exhaust follower? Can it wait after winter?

 

Any misfire is going to be rough on the cats.