I have a d15z1 and when i start it up sometimes, i can hear the engine knock and it tends to go away after it warms up. I just wanted to know if it was normal. BTW i use 93 octane gas.

 

just when its cold eh? sounds like piston slap. i'd do a leakdown test to see if everything is ok, and a compression test. why are you running 93 octane? unless you have like 12:1 compression you don't need that.

 

well the previous owner got the car use to 93 octane and i tried putting 91 and the motor started knocking pretty bad

 

is the engine modded at all do you know? if it is then maybe your getting dtonation with the 91.

 

well it does have intake, 5 zigen exhaust, and test pipe, its using mobil 1 10w-30 full synthetic oil

 

whats weird is that the guy that had the car before put a 93 octane only sticker on the gas latch.

 

the only reason to use high octane gas is if you have high compression. so unless he put high comp pistons it there or something i don't see why it needs 93 octane. i know from my expierience of putting 91 in my car, it seemed to run worse. like i said to some tests to see if anything is damaged