Help With Misfire

[Celeborn]

Hey guys,

Earlier today while driving my 1997 Mountaineer, it randomly started misfiring pretty badly, had trouble making it up steeper inclines, and would surge at idle. I checked to make sure it wasn't a fouled plug, or a burnt plug wire, as I just replaced both.

It isn't throwing a check-engine light, which doesn't make it as simple to track down.

My next thought was that it could be a coil pack going bad, but the issue seems to calm down if I let it cool down for a bit, but once it gets hot again, the misfire comes back just as bad. Not sure if that's a coil pack symptom or not.

It was driving beautifully all morning, till about 3:30pm.

I'm looking for tips on where to go from here. Any help is really appreciated.

You can see my maintenance log here, in case it may be of any help; http://www.explorerforum.com/forums/showpost.php?p=3491322&postcount=2

 

[Celeborn]

Some more info, not sure if it helps.

When it begins to misfire, if you place it in park and listen to the motor, only when it misfires, it makes a ticking sound.

I've read online that it can be anything, from coils, to injectors, to o2 sensors, so I really need some advice on where to go from here, before I start replacing things that may not even need replacing.

I am mechanically inclined to an extent, pretty much all of my previous cars were carbureted, computer-less vehicles.

 

[codyboy]

good evening. i am a novice diyer, so giving my opinion. an all of a sudden random misfire screams timing problem to me; ckp sensors are know to malfunction when hot. and a surging at idle points to major vacc leak enough to cause misfire. i suggest to get scan data with actron at autozone, beware..dont let them make you be a parts changer. also, utube videos from rosedale tech(scandann) have helped me aquire basic diy troubleshooting. (fuel trims, vacc leak diagnostics, coil pack testing, etc.)hope this helps.

 

[Celeborn]

I found the source of the problem, I was sold improper spark plug wires back in December. The boots are not long enough, and the neck of the boot over time, from rubbing on the heat shield, is causing it to arc on the manifold.

Going to install new wires tomorrow, and see if the issue persists.

 

[Flash]

That ticking sound was the spark arcing to the manifold.

I was going to suggest you check the col pack for arcing. Seems heat had nothing to do with it.