MaximaSpd85

iTrader: (14)

A few days ago i hopped on the dyno. on the final run of the night the car shut off as i let out of wot. i let the car sit for almost 2 hours and it finally cranked back up but ran like crap all the way home. on friday, i pulled the plugs, which are one step colder NGKs, and cylinders 2 and 4 were smashed down on the electrode. on cylinder 4 the ceramic material was shattered and a piece missing. the ground straps were intact, no damage to the top of them from what i can see. i drained the oil, no extra metal shavings, nor anything larger than say a speck of sand. i looked down into the cylinders and cant really say that the top of the pistons are damaged or anything. i swapped all new plugs in and the car purred like a kitten and ran normal. verrrry slight tick at idle, but i cannot say for certain that it was never there, although i dont think it was. the tick is random, sometimes it does it and sometimes it doesnt.

fast forward to today, i was driving to work, and all of a sudden after turning a corner and accelerating slightly, the car went pig rich. and when i tried to give it gas it bogged, the car shut off. it will not crank up. im thinking the plugs did the same thing again. (im gonna try to pull them tomorrow). no abnormal sounds, no rough metal sounds, i didnt hear anything happen this time, nor last time. i would assume that if theres mechanical damage that i would probably hear something crazy but im not sure. or could this simply be a case of severe detonation, something to do with timing?

MaximaSpd85

iTrader: (14)

this is a pic of the "better" plug of the two. im not certain but i would think that if a piston hit a plug it would do much more damage than this? im also reading that as long as the correct reach plug is in there that the piston could not hit it anyways so idk

OC_Nooby

iTrader: (11)

I'm thinking if the piston would hit the plug it would do it right away and not over time. Have you advanced the timing? Is it always the same cylinder/s?

Stupid question. When your putting in your plugs are you dropping them in the hole or using the spark plug tool to guide them in then screw em down. If your dropping them maybe this is whats happening. Maybe not as bad but enough to get them close to what yuor showing in the picture.

maxgtr2000

iTrader: (29)

1)That physically looks impossible for the piston to hit the plug unless there was some sort of other damage to make it do so. I'm not an engine guy but just guessing you could have spun a rod bearing, it's in the oil pan, the revolution of the crank causes the piston to travel further up than normal possibly hitting the plug. Do a compression check asap.
2)It also could be the wrong plugs in there, you would have to verify the length some brands of plugs are longer.
3) It could be detonation, I don't remember everyone's setup so I hope you are retarding timing with something that can like an emanage blue or better.

choray911

iTrader: (1)

I've had this happen to me a few times. Nver figured out what was doing it. I just keep an extra plug in the glove box.

streetzlegend

iTrader: (8)

I doubt the piston touched the spark plug, if there was that much play on the rods, pin, journals, you would be hearing CLACK CLACK CLACK CLACK. Id consider it a freak thing for now and put new plugs, then continue to WOT daily and enjoy the car lol.

Perhaps it can be carbon buildup? carbon buildup can be pretty serious, I once had an engine infront of me that did not want to turn the crank, after removing the heads, there was so much carbon that the piston was pushing it up agaisnt the head not letting it move further.

MaximaSpd85

iTrader: (14)

i think its detonation honestly. i pulled the plugs again after this last instance and none of them were like that, so i jumped the gun unfortunately, sorry. it was an unrelated issue that made my car shut off the other day before work. i originally had the timing retarded a few degrees, but while i was on the dyno the pros told me to add some back in, and i think ultimately this was the result. so im gonna pull it back out to how i had it before and let it roll. thanks tho guys

Nealoc187

iTrader: (23)

definitely not pistons hitting plugs, if that were happening you'd have a lot more symptoms. my money would be on detonation though i've never heard of this happening - i'd think you'd have cracked the **** out of your ring lands and/or blown your head gasket before some weirdness like this, but who knows.

QT1 5MT AE

iTrader: (6)

Doubt its the piston. I mean, something internally has to go before that happens and it wont go back to normal by swapping plugs, you'd also definetly feel it. Have you done a compression check? Also as mentioned check the manifold gasket.