Hello everyone, new and really enjoying reading over the vast amounts of technical knowledge. Very specific question though. I work in an auto parts store that ends in zone (name with-held for legal reasons, I think?) and I went to back out of my parking spot when i left for the day and lo and behold! Misfire! I looked down to see my check engine light on (nooooooo) and wound up pulling the truck around the front of the store to check the codes.

P0316. P0316!!! NOOOOOOOO!!!! Why have the otherwise loving and powerful car lords of the sky cursed me?! Me! Whose only crime was to love his truck entirely too much! Spark plugs (Ford motorcraft, of course), wires, new fluids, all the filters! (Even the in-cab air filter) I even use distilled water in my radiator! All this was done when I bought the truck back in november.

The infamous crankshaft position sensor! I'm curious to know if anyone reading this has replaced it and whether or not you had to pull the A/C compressor? I know I have to pull the belt (and will replace it whilst i'm under there) but I can't find anything on the internet that can tell me whether or not i'm going to have to do this.

It's a 4.6L V8 motor.

Any help, tech guides, even sympathy is much appreciated!

 

A crank sensor wont cause a P0316. P0316 is misfire in the first 1000 revolutions and is usually accompanied by another misfire code. You need to do a power balance test to find which cylinder is misfiring if there are no other codes.

 

I once experienced a rough idle while in gear, A/C running at the same time. CEL wasn't yet lit up but I knew it was only a matter of time. Some 50-70 miles of a round trip later still no CEL until just before I was shutting down.

Scanner initially showed only P0316 but there was a pending code P0301, #1 cylinder misfire. Restarted and shut engine down, this time P0301 showed up as a definite DTC.

This is all a long way of saying I agree that P0316 will almost always be accompanied by another P03XX code, pending or actual.

 

My apologies for lack of information. It's also accompanied by a P0302 (Cylinder 2 misfire). If it's not the crankshaft position sensor, what else could be causing the misfire? It hasn't happened since

 

If it hasn't happened again not sure what the question is, can't really advise what fix to apply to "nothing".

Personally I'd check all COP wiring harness connectors making sure they're fully engaged and "locked" into the COP body. There is a locking tab that has been known to break which allows for a sometimes temporary misfire condition. P0316 could suggest this is in effect, only at start up and self-corrects once engine is at idle RPM.

Other than that I'm at a loss for an explanation but then again I don't always go looking for problems (other than PM) that don't recur or happen on a regular basis.

 

Did you replace the coil boots when you did the plugs? If not then you prob have carbon tracks in that boot from the old plugs misfiring and the spark has found a new path to ground. Replace that plug and coil boot and you should be good. Don't drive it with misfires or you will be replacing the cat converter too.