engine miss problem

[dondiesel444]

I have an engine miss I can't seem to track down. It mainly happens in 4th gear, low RPM's under any load, say going up a slight hill or accelerating in OD. The CEL has NOT come on (yet). I have checked the plug wires, and the plugs only have about 15,000 miles on them. It really feels like an ignition problem, is there anything else I can check? Also, once it did this going up a hill for an extended period of time, and I could smell the cat getting hot, meaning a cylinder is not firing and dumping fuel out the exhaust, right? Shouldn't this set the CEL?

The last time I had a problem like this, one of my plug wires melted against the manifold and caused a major misfire, but I can't remember if that set the CEL right away or if it took a while.

Any ideas, PLEASE???????

 

[Opera House]

Pull those plugs

It is the best way to tell what is happening. I just recently had a plug go bad in just 4K. It is almost a guarantee that it is an ignition problem and it may be brought on by an intake manifold gasket leak.

 

[annabanana]

Yup. Coil pack. My '96 5.0 ran like crap for a month with no CEL. It ended up being a coil pack. I've had 2 or 3 packs go out in the 150k I've had mine.

-Section525

 

[dondiesel444]

this is a quick test I do: on the coil pack (with the engine running) and pull the plug wires off, one at a time, and see how the engne repsonds. if the cylinder is firing ok, the engine will usually miss and shake pretty bad. Each cylinder reponds diferent, pulling some plugs the engine will shake only a little and some it will shake pretty good. also you can see/hear the spark jump from the coil pack to the plug wire as I pull it off. That is telling me the coil packs are good, but only at idle, I guess under a load one may be malfunctioning?? Each coil pack supplies 4 cylinders, wouldn't all four cylinder be affected, seems like my miss is only one cylinder. Sorry for all the questions. But one more, if a coil pack IS bad, will it set the CEL eventually or how else will I know the pack is indeed bad??

Thanks.

 

[DrPhibes]

Had the same problem recently, new plugs (Autolite double platinums) and new wires were the fix. Cleaned the MAF while I was in the neighborhood. MPG's went from 15 and change, up to just under 19. Plugs and wires are cheap compared to the time you might spend trying to diagnose a problem with them. I would definetly suggest the use of the OEM style of dual plated electrodes, the generic Champions I had removed had badly eroded center electrodes that had increased the gap considerably.

Tom

 

[dondiesel444]

well, the CEL came on today. I guess I'll have to find somewhere to read the code tomorrow. I'll post the code, if I can find someone to read it at a resonable price

 

[TPLYNCH]

Autozone will read for free if there is one near you.....