Contour Enthusiasts Group Archives Forums General Troubleshooting blowing spark plugs like crazy

This is the weirdest thing, but 3 times now, and the last time the plugs were installed by the dealer, (who accused me of breaking them as I was installing them, like THAT could happen) my Zetec ATX runs fine until I turn the a/c on, then it starts stumbling, missing and bucking. When I pull the plugs there is always 1 or 2 that are broken. The insulator is cracked all the way from the top to the bottom. And there are carbon blow-out marks along the crack, where obviously the electrical spark is leaving the plug. The first two times the dealer said I did it as I was installing them incorrectly, but the last time I said "OK, YOU install the plugs after you put it on the diagnostic scope". So they did, and it ran fine, for 5 days. Yesterday I hit the a/c switch, and it immediately started missing slightly, but the time I got it the 20 miles I drive home, it would barely run. And finally, fianally, I got a CEL. But I know exactly what is wrong, I know the plugs will be cracked. The dealer said it was not possible for that to happen, obviously he's wrong, but what does ? I have NEVER in my life heard of this happening. It looks like there's been 20 million volts run through the plugs, the crack is big, and very black. And yet the car checked out fine on the diagnostic tool. What the ??????????

I've been working on all sorts of cars and I haven't seen or heard of that either. It sounds like a real bad short. It might be difficult but check the ignition wiring and the A/C wiring for crossed wires. Check the fuse/relay box under the hood for blown/burnt/melted fuses/relays. Sorry for all the ///. Try to follow the symptom to the problem. Start at the plugs and work you way through to the A/C. Pay close attention to power supply wires. Make sure to follow as many of the wires as possible. Let us know what the problem was. Hope this helps.

One more idea, Ken. Your coil pack should have a ground wire connected to one corner. Loosen that bolt & tighten it up again, then track the wire to the other end to be sure that it is not rubbing other wires & such.

This has be baffled ... wish I could look at the car & get my hands dirty on it.

Measure what voltages the ingition coil is putting out. Maybe get a computer and obd 2 scanner and scan for u'r own info.

This gives me another idea. Remove the coil pack & check its resistance is within specs. Check your plug wires for proper resistance within specs also.

I'm gettin' out the Haynes Manual & poppin' the hood on my daughters ZX-2!! Dammit, this is gonna get resolved!

I talked to a guy that used to engineer for Champion (one of my older brothers contacts). He said that the bursting insulator is not an unknown phenomenon. He told me that a damaged boot on the plug wires can cause this to happen because the arcing causes the plug to heat up way beyond normal limits & POOF the electrode expands bursting the insulator.

Solution:
Replace plug wires AND plugs at the SAME TIME. Set plug gaps to less than factory spec, specifically he suggests 0.046 to 0.050 (err on the lower side of the range). He said the narrower gap will cause things to run a little cooler, thus helping to prevent the excessive heat buildup.

Based on the information I relayed to him, he also suggests double checking the resistance in the coil pack. If its outa spec the voltages can DOUBLE in order to compensate & that will also cause a quick build up of heat in the internal workings of a plug. (sounds like this ties in to the arcing thing in the first paragraph)

Ken, we're gonna kick this in the butt dude!!

You guys are awesome, you and Kermit, thank you.

I talked to the service manager this morning. I was just amazed at what he said. He called me and said, and I quote; "well Ken we found another one of those blown out plugs, so we're going to replace it". Well DUH !!! I could have SWORN I was JUST at the dealership (I was) and talked to the servc mgr personally and said "now look Pete, this is the fourth set of plugs. I've paid for diagnosis time after time only to have your guy say a plug was bad and he replaced it, for $160. I NEED for you to find out WHY it's blowing plugs, instead of just replacing them and saying I broke them putting them in". After he called me I couldn't speak for a couple seconds, I was so stunned. But I managed to get out; "Pete, I KNOW there's a bad plug, can you find out why" ? He said he would look into it,,,,, good grief, see what I have to put up with ? And this is the BEST Ford dealer around, sad aint it ?

great. Now we've got the "experts" in on it. I wonder if they come up with anything different that what Mike (Champion engineer) said. I certainly hope its that absurdly simple.

Yep.... at least I'm not feeling all alone on this problem!

After my car sat for the entire Labor day weekend I drove it only to discover that the #4 cylinder is COMPLETELY dead. There is no spark coming from the coil pack at cylinder #4's post. I plan to buy a coil pack, wires AND maybe new plugs this afternoon. We'll see!!!!

I was also wrong when I said that my alternator was putting out 18.25V. I checked it today and it is putting out 14.5V which is within range.

This is SO stupid!

I asked the guy at AutoZone (this guy actually is fairly knowledgeable!) and he said that he has never heard of a plug breaking thatt easily.

The "expert" explanations does make sense though.

DB