Ever seen a plug leak?

[joe_db]

This is a weird one: I was wondering why my tune-up generated such a large increase in power. Not complaining, but I got a lot more than I expected.
Looking at the old plugs, I seemed to find what looked like an exhaust residue trail on the porcelain of #1. What the.....
I swapped it back in and gave the engine some MMO for a smoke test. Sure enough, smoke was coming out around the insulator. Not from the plug threads, up top around the insulator.
I guess it makes sense a plug could do this, but I never heard of it before.

[Dave Neptune]

The plug is cracked or broken inside, either the porcelain or the metal/porcelain seal allowing the leak. Just replace the plug.

Dave Neptune

[joe_db]

Already done