#3 cylinder misfire

[jwrezz]

I felt a little mis, then the MIL came on and I plugged in the AutoXray. Trouble Code P303, misfire in cylinder 3 which I believe (according to the distributer/coil paks) is pass side, back cyl. I haven't had a chance to pull the wire or plug, and it seems like the problem is very intermitent (I cleared the codes and the MIL took a full day to come back on). The problem is most evident on cold starts (high idle) and when driving at partial throttle (very little). When I get on it, the mis seems to disappear. Any ideas?

 

[jimmiecakes]

I'd start with retorquing the lower manifold and see if you need to go any further....

 

[mrboyle]

I'd look for a bad plug wire. The #3 cylinder is the closest cylinder to the firewall on the passenger side of the engine.

 

[nosaj122081]

Yeah, first I'd look at the plug and wire... On my Mustang I accidently cracked the ceramic with the edge of the socket, couldn't even see the crack, and it would occasionally cause it to run bad (although it isn't as obvious as losing a cylinder in a V6, you could still feel it occasionally). Check your gaps too.

What kind of plugs are they? I absolutely HATE Delco plugs with a passion. I had a brand new set in one of my Talons and it would bog severely on occasion. I pulled the plugs, and they were in perfect condition, gaps and all... Swapped in NGK's, ran perfect. Threw Delcos against the wall. Same with my Explorer. Had an occasional miss, swapped plugs to find those hideous Delco POS's. Gaps were fine, plugs looked new. Put in Bosch's, miss goes away.

 

[jwrezz]

Well, I pulled the wire and grounded it, plenty of spark. Pulled the plug (Bosch P+4) and there it was! The center electrode ceramic was cracked 3 ways. I think the 4 prongs actually helped me, they held the pieces in place. I hope I don't have any ceramic bouncing around in my cylinder. Brought it back to pep boys (only like 8K since I put 'em in) and they took the old one and gave me a new one. Cleared the codes, rescanned, no problems. Now we'll see if this plug goes bad. then I'll know it's the engine, and not the plugs! I hope not. thanx for the help!

 

[wdwacht]

Uh oh, this just happened to me and the check engine light was blinking! Sure enough, code 303. WAHHHHHHHHHHH!

 

[jwrezz]

Alabama cylinder head is your friend.

 

[wdwacht]

Uh oh, this just happened to me and the check engine light was blinking! Sure enough, code 303. WAHHHHHHHHHHH!

It was the damn Ford Motorcraft sparkplug that was only about three months old! It looked like it was fouled and burned. I reset the CEL with my little computer and so far <knock knock> no more problems. YAHOO! I would have been totally bummed if it had been the manifold gasket.

 

[jwrezz]

It'll happen again. You'll reset the CEL, and cross fingers, it'll happen again. I did the same thing. Pray it's just the gasket, and not the cracked head. Mine cracked right between the valves by the spark plug. New heads (better casting from what I'm told), and some engine upgrades and now all is right w/ the world. Shoulda just put a 5.0 in there tho.