TheOtherEric

I was poking around the engine compartment last night with the engine running, and as it got dark outside, I noticed the little blue flicker of a spark right where the rubber boot of the king lead meets the distributor cap. That can't be normal, can it?! I didn't see this on the lower distributor cap.

My worry is that there may be a problem in the distributor causing the king lead to short to ground on the distributor cap, causing me to run on 6 plugs instead of 12. Anyone ever see anything like this?

I should point out that I replaced the distributor caps and rotors about 2000 miles ago and didn't really notice much change in engine smoothness.

mike cap

Eric,

You could have a bad cable end or maybe the lead just isn't seated all the way into the distributor "socket". Did you try pulling it out and re-seating it? If the cable isn't seated into the socket properly it could track (arc) all over.

Ron

Maybe you plug wires need replacing. Why don't you start your engine and with it running spray from a spay bottle a fine mist over the plug wires. If you see any arcing the wires probably need to be replaced.

TheOtherEric

I'll have to try reseating it. At 40,000 miles I may need a new set of wires anyway. $440...ugh.

So apparently this arcing is not abnormal for old wires. Would I be correct in assuming that I'm losing lots of engine power?

Derrick B.

Hmmm, doesn't the 30k mi service include new wires?

Could the distributor cap merely be cracked?

Ron

I've seen a couple of older Porshes like 12 or 14 years old that did that arching, but they had way more miles than yours. I am not a professional mechanic so my experience is limited.

Those cars also were not running smoothly as a result of the ignition wires arching. And yes you definately will be losing power if they are arching badly.

mike cap

Eric,

Engine heat and time degrade the insulation on the wires and the high voltage (what is it 40,000 volts?) loves to go to ground. So the arcing is not unusual on old wires, but 40,000 miles isn't really old. I asked my shop at my fall service (27k) about a precautionary change of wires and they said that the quality of the OEM plug wires was very good. They said to expect 70k plus for a reasonable service life.

Even with two plugs per cylinder, I think you would feel a mis-fire caused by a bad plug wire. Does the engine pull strong under acceleration and heavy load?

Its probably just a poorly seated wire from when the caps and rotors were changed.