I been driving my 03 Expedition 122k miles for a while and all of a sudden the CEL starts flashing and the car is misfiring. I went and scanned the codes and got


p0307 Cylinder 7 Misfire Detected
p0304 Cylinder 4 Misfire Detected
p0174 Bank 2 System Too Lean
p0171 Bank 1 System Too Lean
p0316 Misfire Detected on Startup (First 1000 Revolutions)


I erased the codes and the same ones came back. What do you guys think it is? Replace Cylinder 4 and 7 coils ?

 

I'm in the same boat, $10 bucks it's the C.O.P.s
Coils over plugs. Accel Automotive makes replacements and a set of 8 will run around $266 bucks at AutoZone, NAPA, CarQuest, or O'Reiley's auto parts in my town.

The thing is it will take two days of disassembly to get down to these guys to R&R the coils. Since your down there, install a set of good plugs.

There is no easy way around this problem...so tell me, does your Expedition run really well when it's stone cold...mine does the best in zero degree F weather. It loves it, until the engine warms up and the internal wiring within the COP's starts to expand and open up causing misfires.

If the 'confuser' says a few are bad, replace them all. A very common problem. I'm coming up on 300,000 miles and have been misfiring since last summer...and the 'check engine' lite says on and some times flashes...every time check, the engine is still there.

Have to wait for good weather before I disable my 1997 ride for a few days. I'll have my bullit proof 1930 Ford Model 'A' to make parts runs in. LOL.

skip.