I just changed out my old plugs and put in my NGKs. When I pulled out the plug closest to the distributor, I noticed that the tip of the plug had been bent....there wasnt any gap. So I took a flashlight and looked down the hole and sure enough! there was a small "ding" on the top of the piston! I double checked and made sure that the spark plug was the right one. What the hell caused this??? I checked the other 3 cylinders and the pistons were fine. The engine runs perfect, but I dont know if the ding on the piston is going to give me problems down the road. Does anybody have any idea as to what caused the piston to smack the plug?

 

Detonation...

 

A little more specific? I just checked the new ones after driving it for awhile and It is still good. Hasnt hit the new one.

 

Detonation blows holes in pistons not little dings. and if it was detonation why would it bend the spark plug node ?

as for why the plug hit the piston is anyones guess maybe the gap was excessive, i really dont know

 

Yeah I doubt it was detonation. The ding is REALLY small! I know what holes look like in a piston because thats what killed my 1st gen DSM. I dont know, maybe the plug could have been a "type o" from Bosch and was too long or something???? Who knows.... Well I have had the new ones in for about a week now and I have been pulling it everytime I get on the gas to inpect it. Ive done it twice now and everything looks great!