Strange thing happened after a tune-up on my car over the weekend. Got all eight of ‘em done, I then changed the air and fuel filters and the cap/rotor. Car fired up and idled perfect as usual, so I figured all was well. Did dirt bike maintenance for the rest of the day…

Fast forward next morning. I took the car to drop my older kid off at Hockey practice and the car ran flawlessly as usual. Half way back home it started missing on one of the cylinders. Thinking a plug wire fell off; I continued home and checked ‘em all. They were all tight so I started un-plugging fuel injectors to find out which cylinder was the culprit. One by one on the left-bank of the engine, I could tell they were all fine as the engine stumbled a bit as I pulled off and re-attached the injector connectors one-by-one. Moved over to the passenger side and found that cylinder #4 didn’t change the idle a bit as I pulled off its connector. Good. I Found the cylinder at least...

Thinking the worst, and since it ran perfectly for about five miles, I figured it couldn’t be a spark plug. I thought that maybe when I changed the fuel filter some crud got in the fuel line and perhaps plugged up the fuel injector. But you gotta check the in-expensive stuff first. Perhaps it’s just a bad ignition wire.

I pulled the plug wire off #4, found one of the old plugs from the trash, grounded it on the manifold and started the car. Good amount of electricity as the spark was bright blue and snappy like it should be, so it’s not the wire. Perhaps it’s the new plug? Yanked out the brand new plug in #4, stuck the old plug in it and connected the wire, fired up the car and it ran perfectly. Found the problem. Bitchin! The brand-new plug failed. Cheap fix!

I then took a real close look at the new plug and found a teeny tiny metal filing shorting across the gap on the plug! No thicker than a hair. Not a big fat human hair, either. More like a fine hair found on a kitty cat. In all my years of wrenching I’ve *never* seen that before. Cleaned the plug, put it back in #4 and the car runs perfect.

What are the odds of a metallic filing finding its way onto the electrodes and welding itself there!

Amazing.

 

Ya know, it's like the bumper stickers say.... "..It happens".

More likely, the little shard was attached to the plug, maybe just some schmeg left over from mfg, and just worked its way loose and got stuck there after a little while of running.

Good logical troubleshooting, by the way. The man who wrote my signature would have been proud of you!