Some time ago I posted about a problem I was having with my 93 5.7L TBI that is in my jeep. Ran fine except I had a stumble/miss at idle....

Checked everything....(I thought)....put an OBD-I scanner on it...everything looked fine. The ONLY thing that gave me any indication was the timing...at idle, when I got the stumble I would see the timing jump from about 16 deg BTDC to about 22 deg....was this the cause or just the effect?

Compound this with....I could disconnect my timing connector and no miss...or I could unplug the MAP sensor (goes into fail safe/limp home mode) and no miss.....

Well....I was replacing the dist over the weekend (different reason...I tweaked the base plate during the engine install a few years ago).

While hooking things back up I noticed a blue crust on the dist terminal for the coil wire....mmmmm....look at the coil wire and see some blue crust in there....could it be oxidation caused by arching?

I pull out the ohm meter....the wire from the coil to the dist is OPEN.....totaly OPEN.....best I can figure, there was enough voltage to arch across the open......most of the time....

Replaced it.....runs like a champ. I'm willing to bet that I won't be borderline on my HC #'s on my next smog test.

Why did I not think of this? Because it was running pretty good....except for the miss.....thank god I didn't go into 'shotgun' replacement mode....that wire is one of the last things I would have replaced.....it was a new plug wire set...