Hey guys, something strange happened!

I was running the cheaper Bosch plus, about $1.19 each, gapped at .05, and it worked at first but then something happened...

We were draining the radiator and flushing out the water jacked and everything before putting in new water. The reason was because there was soot in the coolant from when they hot tanked my intake manifold. The water passages in the intake manifold had a bunch of soot in them and turned the coolant black. I wonder if that affected the cooling ability of the coolant?

Anyway, we had a hose in the radiator washing things out and the engine running, and some water got on the spark plugs and it started missing. The next day, everything was totally dry but the engine was STILL missing.

I started unplugging wires to see which cylinder was not firing and it was #3. Fearing the worst, I quickly checked compression - it was fine on that cylinder. I tried hooking up the spark plug outside the engine and the plug was definitely sparking. However, when I screw in the plug and run the engine, that cylinder misses. So, I swapped that spark plug with cylinder 1 and then cylinder 1 would miss. So the problem moved around with the spark plug, so I knew the plug was bad.

I don't really like those plugs anyway, they came gapped at about .03 and getting them to .05 was difficult, I did not touch the center electrode, I used needle nose pliers to carefully adjust the gap, but maybe I damaged something somehow. So, I just bought a set of Motorcraft plugs, and guess what? They came gapped at .044 already, so I just kept that gap for now. I did test them all to make sure their gap was all the same and it was, all of them .044 so I put them in. Engine runs smooth again!

I wonder what was wrong with that plug? There is no visible damage, I can't see anything wrong, and the plug sparks fine when you test it outside the engine. It's a nice brown color that doesn't look like it was getting too hot or anything. Crazy...