Fixed p0304

[alohamonte]

My explorer was running like crap the last couple weeks. Stumbling idle, lack of power, shifting issues.

Yesterday I got a CEL and read it to be p0304 misfire in cylinder 4 (keep a cheap scanner in the glove box).

I had the plugs, wires done last summer and the coil two years ago. So I'm thinking intake or head gasket problem. And I had images of getting a new truck swimming in my head as a I limped home.

I inspected the spark plug wire. Looked good. I pulled the plug and there was resistance on each turn getting it out. Wasn't coming out smoothly. I was worried it jumped the thread. The plug was gummed up bad with carbon and so was threads in the head. Shined a flash light into the hole there, and it was like a crescent moon shadow from the junk. I liberally applied carb cleaner to the head's spark plug port. Put the old plug back in. Started it up. Better. Took the plug back out. It was all gummed up again. I resprayed it. I started it without a plug to blow out the crud. Put a new plug in. Drove perfect this morning.

Oh well, no new truck for me.

But now I have to figure out why #4 fouled after a year and maybe 10,000 miles. Something to keep an eye on.

 

[Lonnie-S]

Did you happen to check the compression in that cylinder? Maybe it's blow-by from the crank case? I had a Mustang 3.8L V6 that did something similar on the #1 cylinder, but it didn't consume a lot of oil or smoke at all, so I did what you did, cleaned the plug and put it back in. Six weeks later, I had the same problem. That's when I checked the compression, which revealed a weak cylinder.

Cheers,