happened right after 1st thru 4th pull. no odd sound or loose of power untill after i began to slow around 4-5 k rpm. good afr, comp 280 cams, buschur racing icp & fmic, hks hiflow intake and 3 " tbe.

 

The small speckles are generally a tell tale sign of detonation, so if you're saying the AFR's are good then I'm going to guess a a bad tank of gas. AFR's won't change, but car will knock itself to death. Good luck with everything, how's all of the other cylinders look? Could be a faulty injector in one cylinder or something similar that let it go lean for a little while, but the other cylinders kept the AFR's in a fairly normal range that caused you not to notice anything.

 

all other cylinders have damage, something defiantly went thru them. i think when the 4th cylinder went down and quit combusting the vacuum started to suck little bits back into the intake manifold and caused that damge. if it was detonation, way would it not just melt down like normal. what made it chunk out?

 

share some more details.... was the car tuned? stock turbo? how much boost? etc...
I wonder if the detonation was that bad, wouldn't the knock sensor put the car in limp mode and prevent such damage?

 

How many miles on that engine??

It is def detonation, but it looks like the ring land seized up and that's what caused it to blow apart. I have seen this before in evo's.

What was your knock count? during the runs??

 

yea im going to say the tune was the issue, lots of detonation on the pistons. And No they wont melt if they didnt get hot enough.

 

stock turbo tune is uncertain. i've had the car for two years and never messed with the tune, but nore did i ever add a part for it to be retuned. so no one thinks the dings are from debris from the missing piston chunk.? to me i think the piston did all the damage... no?

 

pingin like a ****.

could be bad gas, bad injector, fuel pump issue. didnt read if you had a wideband or not. i assume not as you havent messed with anything.

****ty deal, no matter what.

 

If the car wasn't tuned thats your problem. If it was tuned then I would find a new tuner

 

Do all the cylinders look like that? hard core detenation..... probably it cracked... and it only came lose on the decel.

 

make sure all your lines weren't leaking, MAF sensor etc

 

Probably bad gas/injector, time for a big build!

 

i had damage in every cylinder but i know for sure it was from debris due it its odd imprints in left in the head....
...98k btw
....i dont have a laptop hooked into the car so i don't know knock count, but it was reading knock a few days before that happened cuz mu cel started flashing. so i checked and replaced my plugs..

 

Plug might have broke off. i have seen this alot. the tip of the plug comes off and creats the dibre your looking for.

 

my distantly odd thoughts:

not enough oil causing the pistons to attempt to seize up but with you getting on it a bit it forced it, broke the piston, and eventually did all that.

its out there, but thats what im thinking