P0308 and P0316, Rough Idle, Changed Oil
 

I'll keep it brief. My truck is a 2006 with the 5.4.

I am currently running a few tests to see how my truck performs with 5w-30 instead of the 5w-20, since it was burning 5w-20 at a rate of a few quarts per oil change.

I made the swap to 5w-30, and within a few days i got P0308 and P0316. Misfire Cylinder #8, and it occured at start up (first 1000 revolutions). Previously I had never had codes.

Other facts:
-Truck has 166,000 miles.
-May still have original plugs
-I get the rough idle at stop lights
-Truck runs much smoother with 5w-30. Diesel type ticking has quieted, idles a little smoother.

Any help or ideas would be appreciated.

change plugs

Thanks for the advice. That was the plan to replace spark plugs.

I have been doing research for the past few weeks. Did the passenger side tonight. Broke 1 plug, 3 came out fine.

Here's my advice and trick.

Loosen plugs with a quarter to half turn, spray carb cleaner and some pb blaster in the cylinder. Wait a while.

Loosen plug a few more turns. Then tighten, then loosen, then tighten, then loosen. Take your time and they should come out better.

If you change the plugs with the motor hot they usually don't break. Do 1 at a time and run the motor between each plug. It has worked very well for me. Good luck!

another vote for plugs.

Burning a few quarts between oil changes is catastrophic! I would address that issue before spending any money on other things.


That said, I would also reset the computer and do a proper relearn.

All 8 plugs changed out. Broke 2. Truck runs smooth as can be. Still monitoring the oil usage after making the change to 5w-30.
So far 800 miles into the new oil and showing no signs of usage. Will continue to monitor

Had the exact same thing happen to me.

2006 5.4 with 204xxxkm.
Swapped over to 5w30 a month ago and two weeks ago I started getting a misfire. I got code P0358 problem with cylinder h primary/secondary circuit. Swapped out the coil and no cigar so brought it to ford to get the plugs changed and it fixed the problem. Still don't fully understand why it wouldn't give me P0308 though.

Got the P0308 code again last night. Was idling a little rough and was clearly an occasional misfire. I'm thinking my next course of action is to replace #8 coil.

Any other advice?

Try switching #8 coil with another and see it the miss follows. Also may want to do a compression test.