I have just run my first DE track day with the 15% pulley upgrade and the engine ran well with my Unichip set for the B map and running 104 octane race fuel. When I pulled the plugs ( stock BMW plugs) they had a rust color to them. On higher mag the four outside electrodes had a fine beading of a dark hard substance. Is this bad or good? Should I be running colder plugs with the SC pulley? Does any one know a good source of info about spark plugs?

Mike

 

The rust color is fuel additives - nothing to worry about. The fine beading sounds more concerning though. A picture would go a long way to helping diagnosis. Be sure to do a 'plug run' before you pull the plugs.

Plug run:
Warm the car up properly and then go out for some good high rpm blasts. It'll take off any fluffy black cabon that can build quickly from short trips/long idling.

Did you notice any popping (not exhaust burbble) while you were driving? If the "beading of a dark hard substance" turns out to be silver in color and very round it could be aluminum. ...Which would imply detonation or similar.