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Did my plugs because my 11PSI Supercharged S2000 started to misfire (audible ignition breakup) at higher load but had popping which told me there is still fuel being delivered.
Pulled the plugs which were all torqued great but the gap was way off from age. Both sets are 1-step colder than OEM, so NGK 2668 we all S2000 guys&gals love.Spark Plug closest to the firewall , the only one that had an obvious early signs of overheating.
Insulator surface is pure white, but no burning gasses deposits like you'd expect in severely overheated plugs. Tip and ground looked ok even though the ground was lighter in color than others and stayed the same throughout the tip and around the base. I don’t believe excessive gap would cause overheating of the plug, would it? It had the highest gap of all other plugs.
I’m thinking injector and that cylinder running lean? Oh how I wish I had a WB on all four cylinders . Car runs great overall after plug change.
Excessive gap will cause a misfire but won't contribute to overheating. I'd be inclined to think you are running a touch lean given what you've explained. It's possible this is confined to one cylinder. What is the AFR under full load? The heat range is probably about right for the boost I'd think. I'd suggest fitting a new set of plugs and checking all of them after a dyno pull or a full power run on the street.