So i tried some NGK BPR 7ES (one range colder) plugs today gapped at .028". I installed them all and went for a quick drive. Mostly WOT to get a good reading. I pulled one plug and the grounding strap almost looks a yellowish color the ceramic was still all white. I cant seem to find any good info about a yellow deposit. In fact the coloration was so different that i cant find anything that says if its a good or bad thing. I went ahead and used the stock plugs because they were a dark tan color which is perfect. But i figured that a range colder would make the plug look like it was running rich if anything at all.

Does anyone have any insight to this? Should i only use an iridium plug? I know this NGK was a copper plug. Anyone have the stock number for one range colder ngk laser iridium for our car?

 

i'm not positive but i don't think BPR7ES are one range colder - maybe you want the BPR8ES?

i think the NGK part # for the colder iridium plug is BR8EIX (anyone confirm?)

can't speak for the BPR8ES but i did put in some pre-gapped Denso IW24's (iridium, one range colder than stock) and they seem smoother than the BR8ES i was running