pepper the plugs 

a common condition in racing engines when there has been to much nitrous oxide, not enough enrichment fuel, to much ignition timing, to much boost, or any other tuning error resulting in small black dots (tiny pieces of melted piston) resembling pepper on the spark plugs.

driver; "did we pepper the plugs?"
crew chief; "yea, better back off the nitrous before we hole a piston"

pepper the plugs by Nitrous Jim February 9, 2017