Subaru Twin Turbo question.

spacies_nz, Apr 3, 12:28am
A mate gave me his Legacy TT Wagon to use as a work car. I runs fine but I think it is not boosting correctly. I don't know much about these, but it sounds like all the air from the turbos is blowing straight out the exhaust (loud hissing sound) and struggles in the high revs.

Any help appreciated :)

s.patete, Apr 3, 12:34am
Constantly hissing or just under boost! Sounds like its just the turbos spooling up.How high in the revs does it struggle!

spacies_nz, Apr 3, 12:36am
It hisses only under boost. The revs struggle from about 4500. I mean it should be faster than what it is. It idles and runs fine, just not under boost.

s.patete, Apr 3, 12:52am
Is there noticeable boost up to that point!When the 2nd turbo kicks in does that change anything! It should be around those revs I would have thought, maybe thats shagged, first turbo prob done all it can then 2nd kicks in to provide boost for the rest of the rev range but if its stuffed you will loose the boost.

spacies_nz, Apr 3, 1:03am
nah no change at high revs. it kinda flattens off if anything.I mean it still goes faster but no like I would expect.

meow_mix, Apr 3, 3:35am
Twinturbo Legacy engines come standard with two factory blow off valves, a main one on the intercooler and a second one located near the secondary turbo.It sounds like one of them, probably the second blow off valve, is leaking under boost.

The engines are quite complicated, it could be a solinoid or doo-hicky has failed somewhere in the engine's complex turbo plumbing.

spacies_nz, Apr 3, 4:50am
Cheers. I actually just went for another drive. Its pretty sluggish from 2500rpm. I guess it need to see an expert.

pollymay, Apr 3, 4:54am
Sell it to a yo boi and get a car that won't break cause you looked at it

spacies_nz, Apr 3, 5:05am
Yeah but its just a work car as I don't want to trash mine. So I would rather sort it out if I can.

1fordluva, Apr 3, 6:01am
What year!

spacies_nz, Apr 3, 6:41am
1993 mate

1fordluva, Apr 3, 7:12am
Check the vacuum hoses around thediaphrams that actuate the waste gates for a start,any air leaking or perished lines will not close or release the waste gate to build pressure.
Or the wastegate is stuck open.

spacies_nz, Apr 3, 9:46am
Thanks. I will take a look in the morning. It is making the sound the moment the turbos start spooling, so yeah, it sounds like a vacuum hose off or something is stuck open alright :)

hijacka, Apr 3, 12:22pm
Come on fordy!
Its a 93 so its 0BD1! check the bloody fault codes first you idiot!lol
Unscrew the panel under the steering column and there will either be a white or black plug(male and female) coming off the main loom on the left hand side from memory. Plug them in to each other and count the engine check light flashes.
I wouldn't be surprised if 1 or both of the turbos is stuffed , those come out with vf13 and vf14 turbos and are common for failure given the simple design and age.

pnh4, Apr 3, 12:36pm
weld the exhaust flanges up

1fordluva, Sep 25, 12:04pm
Yeah quite true hyjacka.
I had the gt 4 door do this,was just a hose off.
But many years ago so it would pay to check the codes also.
One the reasons i went away from tt,s lol.