No boost and a sound like blowing over a blade of grass
 

Hi all
Not impreza related but just as relevant. I have a 2004/5 Forester STI (2.5)
A couple of months ago i was taking it to the track when all of a sudden i lost all power and just got a squeel from what i think/thought was the turbo spooling up.
I stripped it down and the turbo shaft had a small amount of play and there was oil going into the throttle body. So i rebuilt the turbo.
Fast forward to putting it all back together. The turbo is nice an tight with no play but spins nice a freely so all is ok with that, i couldnt see any cracks in either side of the turbo so it was all put back together, and as i ripped the stock turbo inlet pipe is tuck a new reinforced silicon unit in.
Thought i had it all sorted. The car started and idled fine, but as soon as i took it for a test drive all i got was the same noise that i had when a month or so previous went to the track and lost all power.
So it feels nothing has been fixed at all.
I have had the boost solenoid off and check that and its fine, the bov is fine and still working. I have done a bit of a diy pressure check on the inlet side of the turbo to check for boost leaks, i found one by the pipe from the bov back into the intake so that is now sorted.
But i have ran out of steam on it, i just cant find the issue i have been over everything twice and cant see or find an issue. I even had it down to TDR in warwick for them to have a quick look over it and they were baffled aswell. They took it out for a drive and said it drives fine and rpm build up is smooth but it feels like the engine is maybe being starved of air instead of a boost leak, i was told to check the up pipe for collapse but not sure if that could even happen, i could understand if it was a catted up pipe but i dont think it is, it has an O2 sensor in the up pipe but not temp sensor, so sure its not catted.

Anyway any help would be great as i am stumped, i think the next step would be to strip it all down again and check it again......

cheers in advance

Dave

Just a quick one check your new silicone inlet pipe that you say you put on isn't collapsing in on itself

Yeah, that looks pretty impossible to collapse, Its not one of these £250 mishimoto ones but it still reinforced and i cant crush it with my hands.
The issue i have is that it was working fine until one morning taking it to the track then all of a sudden lost all boost.
So still has same problem as when it initially broke.
cant for the life of me figure it out.

Split in the inlet pipe? Or in the boost pipe to the throttle body?

Think i am going to have to strip it all back and build it backup again, and double check everything 3,4,5 times.

I would definitely check the up pipe and its gaskets, I had similar symptoms on my v3 sti and it was a blowing up pipe. There was a high pitched wailing sound and lack of power when approaching boost

Aye cheers I think I'm going to have to check it out.
just doing think a blowing up pipe could cause this much loss of power.

It can cause a significant loss of power from what I've heard, as a proportion of the the air being measured by the MAF in the intake is being lost to atmosphere which causes the engine to run terribly and in a potentially dangerous state. Mine was running weaker than a non turbo 2 litre before I got the uppipe replaced!