Ever seen a magnetic spark plug?

A buddy of mine bought himself a 'new to him' Chevrolet truck(( I think he said it's a '98 or '99)) with the V8. The second day he drove it put on the Check Engine Light, so he put a scanner on it and it showed a misfire on number 7.

Since he just bought it, he decided a tune up was in order. When he changed the plugs he said he went to set the plug that he pulled out of number 7 down, and it stood up on the electrode. Basically it was so magnetized that it had enough pull to stand up where it would have typically fallen down. He told me about it, and then showed me over the weekend. In the week since he had changed it some of the magnetism had died off, but there was no doubt that it was still magnetized enough to stick to something with one of the flats on the hex.

My buddy and I both though it strange that the misfire code was thrown on the cylinder with the magnetic qualities. At the same time neither of us can figure out how what is basically an electrode with current flowing straight through it, could become magnetized when it usually takes multiple coils to cause that to happen.

So, my question here is, has anyone ever seen this happen, and does anyone have any idea how it could have happened?

That's real common on the Essex Tri-directional, caused by the interaction of the neutron flux limiter and the gamma ray inverter when the commambulator is in phase modulation mode. Never heard of it on a Chevy, though.

You're jumping to conclusions a bit. There's no reason to believe there is any connection between the misfire and the magnetism. And the plug may have been magnetized before it was installed in the engine.

The current through a spark plug is very small. Not enough to magnetize the plug. But it's conceivable that eddy currents are induced in the cylinder head which could magnetize the plug over time. What would induce such currents I can't say.

I was gonna say the exact same thing

I agree with NarkB and the source of the eddy current could be a discontinuity in the head; as in a crack.

Good job, Fred - I couldn't remember all that information from the ETD Diagnostic Manual.

I could see on the newer engines with a coil mounted directly on top of the plug where is would magnitise over time.

We didn't really reach any real conclusions on the cause, just found it strange that the misfiring plug was the one that was magnetized.

As far as the plug being magnetized beforehand, that's a good question. Personally I've never seen one that had been magnetized, and I've installed a lot of them in my life. Too, I could understand it being magnetized beforehand, but if that had been the case, why did it begin to loose magnetism once he took it out?

In the end I'm guessing it's one of those things that's simply going to have to remain a mystery.

You can tap or hit on the end of a pipe or steel rod with a hammer and magnetize the pipe or rod... It doesn't always necessarily take a current of electricity to magnetize something.

Being that the spark plug lost some of the residual magnetism after you removed it from the engine tells me that the head must of magnetized it. Did a new plug correct your problem?

(quoted from post at 03:28:05 03/17/15) You're jumping to conclusions a bit. There's no reason to believe there is any connection between the misfire and the magnetism. And the plug may have been magnetized before it was installed in the engine..

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You can find out by switching the plug with another and re testing. I have fixed others bad tuneup issues by replacing defective champions

Sounds as Fred studied that chapter very well. Give him an A+. LOL

He's probably got one of those gadgets that you put on your fuel line to align the molecules too.