jb2012

I am at a loss at this point, in more ways than one. I chased an intermittent misfire for weeks and found out there was a short in my main engine wiring harness, causing major major misfires, I mean this thing barely ran. I replaced the harness and it is almost back to normal, except a slight misfire at idle with code p0301. I have cleaned my MAF and throttle body, I have replaced the erg, as well as the tube, I have replaced all spark plugs, as well as coil boots. I have swapped coils and injectors around, and I still get a p0301. I know I am getting spark to the spark plug after testing it, I am getting around 13 volts to the injector, and have tested and confirmed the cylinder for compression. What in the world else could it be?

Bruski

This is a good link I found, maybe it will help.
http://repairpal.com/OBD-II-Code-P0301

jb2012

that is definitely a very informal link! however I've tried all of that already

wavector

I had a misfire that coded and it turned out to be a bad spark plug wire that was almost burned in two by the ERG tube being so close to it. The insulation on the tube was moving to the side allowing heat to direct itself on the spark plug wire. Insulating the tube along with replacing the spark plug wire solved the problem.

Hope this helps. Good luck.

techrep

iTrader: (1)

try another plug...check the gap and torque it...if that don’t work...look at the CATS. Just went through this with my son’s ...unfortunately ...we found a bent or burnt valve.

jb2012

wavector- I just replaced the main engine wiring harness I.e. the plug wires last week. lol so I am eliminating short

techrep- I'm just gonna buy a new plug and coil, just to be absolutely sure, but wouldn't the compression test eliminate the internal problem,such as a bent valve?

techrep

iTrader: (1)

Yes... I was just saying ...that's what I ran into last week... glad you did not !

jb2012

good gosh I feel bad for you man. what happened to ford engines being reliable?

techrep

iTrader: (1)

it was a 5.4 2v and it had 225,000k miles on her . so she lived a long life

Summers22

iTrader: (2)

"I have swapped coils and injectors around, still the code". Plugs are known to be bad right out of the box. I would start with just the #1 plug replacement. If it was the COP, when switching #1 to another cylinder, the code would have moved with it. I think you have narrowed it down nicely to plug #1.