So I changed the plugs and wires today and was a little surprised at how the number one plug looked. I've never seen a plug come out of the car this way since I've owned with all the sets I've put on it. Here is a picture:



The other three plugs looked normal with a nice even light tan color to them. What do you guys think? It wasn't oily...kinda caked somewhat hard stuff...running rich maybe?...

-Darwin

 

The ol' haynes manual suggests carbon deposits. Has it overheated any? Mine runs a bit rich and they have some of that dry deposit, but not nearly that bad.

 

No, it doesn't overheat. It'll climb over halfway up the gauge occasionally, but always cools right back down. Like I said, the others look great, this is the only one that isn't so great...

 

could be bad rings or valve guides. take a leakdown.

 

When mine looked like that, I had just changed the oil after having fun fuel injector cleaner through the gas tank and a bit of marvel mystery oil in the oil for a few hundred miles.

 

I have run MMO thru it a few times (fuel and oil).

 

well that makes sense, its actually probably the MMO.

 

Only thing is that it's only one cylinder that has it, I'd think it's at least affect the others a little bit.

 

Now that I can't explain. If the car is behaving well, just replace the spark plugs and see if it happens again.

It could be that that one spark plug was misgapped or defective.

 

Yeah, I noticed the gap was pretty big, over .o40...that's never happened to a spark plug I've been using before.

 

sure it can, cylinder 1 has a little more ring wear probably, also since the plugs are 3 years old you coulda had a leaky injector causing the deposits

 

i'm also thinking leaky injector.