Blown headgasket...

Well heres my question. My car has been acting funny lately, i can boost fine once warmed up as long as i dont really push it hard more than once or twice.... then it seems to be going into some sort of fail safe mode... and im sure its not the ecu doing it... it seems mechanical. At first i thought it was the turbo vsv... but i blocked that off again (had it hooked back up for a while). Now i took it for a drive and the same thing... it boosts fine through 4 gears, and i could do it a few times (its boosting 12psi). But then out of no where the motor kinda changes all together where it seems to be limping, when i boost it it will build full boost but it isnt actually making any power, almost as if its hesistating or leaking off somewhere. Also when i start the car it does this until it is completely warmed up.

Im wondering if this could be a problem with my headgasket having a small crack in it that seals for a while when it is fully warmed up, but then opening back up after more pressure is put on it.

Also if this is the case how hard is it to do with the motor in the car?

And finally, i havent compression tested it yet, i dont know if i want to (dont wanna find out the results...lol) but i will do it here in a while.

well i compression tested it and it came out exactly as it did a few months ago when it ran good

11.25 kg/cm
11 kg/cm
11 kg/cm
11.25 kg/cm

this is all when its hot too...

Pull your codes. You might just have a bad sensor of some kind.

Maybe knock sensor?
Sounds like the computer might be retarding timing.

thats what im thinking.... though im pretty sure it cant be the knock sensor, as it is about a month old (100 miles on it maybe)......... I am running 92 octane instead of the 100octane as usual, and have a jdm ecu/harness with my timing set at about 10 degrees. Im thinking its sensing detonation and retarding the timing... but who knows.

If you have a JDM ecu, and are running 92 octane. I would definitly say timing. I am pretty sure it's mapped to run 93 or higher (Ours are mapped for 91).

Might want to add that in next time ( at first). Makes a difference.

lol sorry guys, i tend to forget my car is slightly unique at times... and think that everyone would know my 165 has a jdm 185 drivetrain in it (ecu and all).

But yea im pretty sure you're right, im just burning off this 92 octane in there and then we'll see how 100 octane changes things. My timing is at 14 degrees with the ecu still enabled (have yet to been able to disable timing control to time it, but most people i have talked to said just to figure 3 degrees timing in, and i should be fine)...

Who knows....