Misfire on cyl 4
 

I was on the interstate doing about 80mph. My rpm's were at 2500 and my ears were about to bleed from the exaust, so I put her in 3rd gear(auto) and bring the rpm up to about 3500. I drove this way for about 15-20 miles and my check engine soon light came on. I stopped at the side of the road, whipped out my Diablo, and read the tunes. Said there was a random misfire, and cyl's 4, 5, 6, 8 misfire. I cleared the codes, and went on my way in 4th gear. That was about a week ago. Yesterday, I was driving in town, in 3rd gear, and the same things happen, only this time it is only cyl 4. What the hell is going on with my misfires? What could be the problem, and how can I stop it? Sorry for the long post, but didn't want to leave anything out. Thanks in advance for the help.

RE: Misfire on cyl 4
 

im not too sure but my dads f150 is having the same problem with a misfire on cylinder 4...possibly the spark plug? im gonna check it out sometime over winter break

RE: Misfire on cyl 4
 

I had a similar problem with my '04. When I hovered in a certain rpm range (2600-2800 in my case) I threw cyls 3 & 5 with the random code. I believe my were caused by my UDPs (piggys). I replaced them with Steedas and only had the light come on once since then.

If you recently added the pulleys, then the computer may still be sorting things out. Anyway, I think the crank position sensor picked up a vibration and started dropping cylinders.

It could be coils or plugs, but I don't think so. Way to random. I'd think ECM or sensor.

I can't say that is your problem, but try to replicate the problem a few times and keep track of your rpms when the cel starts flashing.

Did the problem stop when you slowed down or stopped?

RE: Misfire on cyl 4
 

the light quit flashing when i stopped.

RE: Misfire on cyl 4
 

Chances of all 4 misfiring are slim. Probably just a random error.

As for xkon, yes it's probably a spark plug.