New spark plugs burnt

2012 Chev Impala LS 3.6 flex. 109000 miles. At 100,000 miles I opted to change the factory installed spark plugs. I replaced them with OEM AC Delco 41-109 iridium. (Same type of plugs removed. Gapped at .043. After 9000 miles with the new plugs I started to get random misfires (P0300). I pulled out the plugs and noticed that the spark plug tips (not the ground) were burnt off on all 6 plugs. Curious as to what caused this. My guess is that I bought defective plugs because I got them for a great price on EBay. Could the COP’s cause this? Fuel additive? (Sea Foam and B12 ChemTool have been used occasionally but I have used those chemicals before on the original plugs with no damage. There are no sounds of detonation but with the spark plug tips burnt off I’m leaning towards high combustion temperatures. No EGR on this engine. LTFT’s are less than 10. Gasoline octane used is 85-87. Hopefully the pics loaded. Picture of new plug and removed plug

Wow. :blink: All six plugs were like that?

I've done many plug changes on that engine, and never seen one eat all the tips. The only other time I've seen similar damage was on LC9 and 2.2L Ecotec engines that had blown head gaskets or excessive oil consumption. But, it's unlikely you have a blown head gasket on all six cylinders. :silly: And even the worst oil burning LFX's I've seen don't eat their plugs.

Also never seen COPs cause plug damage in this way. I've found this coil design to be pretty darn reliable.

I think you're right to be suspicious of the Ebay plugs. Try a dealer or locally sourced set, if you haven't already. No other trouble codes?

Only troubles code was random misfire. I have bought a complete new set of plugs from an auto part store. Car runs great. I believe I must have bought cheap knock off plugs that masterfully had AC Delco stamped on them. Thanks for your info.

EBay is full Counterfeit clone plugs, but usually branded as NGK. The tips would be base metal steel not irridium or platinum. The tips are the part that reaches the highest temperature so is subject to the most errosion. It isn't just spark plugs I have bought what I suspect were counterfeit Delphi suspension parts. They looked 100% genuine but only lasted 8 months.