I pulled my plugs to take a look at them and found this.



They were all tight. The coil pack boot wasn't burnt or discolored any more than the other three. Any ideas?

 

very common on some plugs, it is just leakage coming out of the one plug, I've seen many engines where all four plugs looked like that. Doesn't mean anything and no harm done, it's not related to any engine issue.

 

I'd say it looks to me like a failure of the internal insulator seal. One possible cause is overtorquing while installing. Another may be simply a defective plug.Below is a link to a cutaway view of an NGK plug eluding to the internal seals.

http://www.rpmoutlet.com/ngkinfo.htm

 

Thanks

 

hmmmm.. that's cool

 

All of my plugs have always looked like that...at least, after a track day or two. Never had any problems.

 

I showed 4 of those with discoloration to my tuner and he said he sees them all day long.

I have run the iridium plugs and seen this on 11 of 12 plugs.