2004 Exp 4.6 misfire codes.

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May 3, 2013 | 11:57 AM

VRC9170

Thread Starter

Mountain Pass

Joined: Apr 2008

Posts: 246

Likes: 9

From: Surrey

2004 Exp 4.6 misfire codes.

In the middle of the Rocky Mountains the “Service engine soon” dash light started to flash and the engine had a miss. We had it scanned about two hours later and it was cylinder number 6 misfire, so put a new spark plug in it. It ran good for a mile then came back on again. Two hours later I bought my own code reader and it read the same code – P0306 – meaning a misfire on the 6th cylinder. I had a new plug in it so decided to swap the coil (one on each plug) for the one in Cylinder five and reread the codes. Sure enough the code read P0305 for the 5th cylinder. I bought a new coil for $70.
We got home yesterday and the car ran perfectly. So today what do I do? I mess with what is working well and replace the other 7 plugs. That means pulling each coil off, replacing the plugs and re-installing the coils. Now I have misfire codes on cylinder 7 and 8. Something to tackle tomorrow I guess. I found the left side has oil on the plugs where the wires connect. I wonder if that can cause the codes? maybe more of the coils are intermittent and failing. Might be an oil leak from the rocker cover gasket. 195,000 KM about 117,000 miles on the truck.
Bob Bates

May 3, 2013 | 04:08 PM

aquanaut20

Cargo Master

Joined: Aug 2003

Posts: 3,263

Likes: 92

From: BC Canada

Check all the lances on the COPS, they may be contaminated and arching.... Philip

May 4, 2013 | 02:46 PM