So I think this has been asked a few times and I've been doing some reading. Anyway here's my story. I was out running some errands tonight and after leaving the last store the truck started running like crap and hesitating. By the time I got home the CEL was on. I threw my code reader on and it told me cylinder 3 missfire. The truck has 114k on it, I bought it last September with 97k and as far as I know plugs, coils, whatever have not been changed. Am I on the right track by thinking that could be the problem. I was thinking I should do it anyway but was waiting till the spring. Any input would be appreciated!!!

Thanks as always guys!

2001 4.6

 

I had the same problem a while back and changed plugs, wires coil etc. Did not help. Check the wiring harness that comes from the main fuse panel. It lays across the A/C dryer and will actually rub through and short to ground. When I checked mine, you could see the burn mark from the wire that actually fed the coil pack for #3 cylinder.

Good Luck!

 

i dont remember if you have cops or coil packs.. id start with new plugs

 

Check the heater hose lines above that cylinder. They have a tendency to leak down in the 3 & 4 holes.

 

X2. Mine was not too long ago, on #4. I threw another hose clamp on each hose, just for a little extra beef at the connections, and I havent had any problems yet.

Pull the plug wire, and check for moisture. Moisture = LEAK from some source, then it is just a process of elimination as to where the leak is coming from.


-Matt

 

Well the short of the story is, spent all day in the garage today, and multiple trips to ford and napa. Changed out all 8 plugs and a couple of the coil boots to just because of cracks, and no help. Then last resort, changed out the coil pack on cylinder 3, and yes, that did it. I'm running on all 8 now! Thanks for the help guys, and everything looked normal. Plugs weren't terrible, none were carbon or oil fouled, so thats good news, and none of the coil packs or springs looked bad, except the failure of 3.