boost leak - likley cause

[avants2turbo]

my s2 avant doesnt seem to be able to hold boost, it peaks at about 3.5k rpm then very quickly tails off, any ideas what would cause this, tired turbo, leaky isv, recirc valve.

See, im not sure its a leak as such, just doesnt seem to be able to hold boost?

[avants2turbo]

woohoo, i got a mahoosive boost leak...

[4WheelDrifter]

Fix it, and test it again. There's often more than one.

[Rusty]

The Zydar Yoda speaks the truth

[avants2turbo]

sounded like it came from the inlet manifold? About the area of the 3rd injector, would you get a boost leak from the inlet manifold gasket, or an injector seal?

[4WheelDrifter]

It's possible. Spray some soapy fluid around there and check for bubbles.
The usual place for a huge leak around the inlet manifold in the throttle body hose.

[m15 vw]

thats a possibilyt keith, we didnt check the hose itself. Might be split underneath then tracking along

[Jonas_R]

You could also use some diesel starter "danish word" and spray it around the places you suspect have a leak. You do it while the car is running in idle and it will make the engine sound change.

[quattrostyle]

brake cleaner works aswell AFAIK

[Jamo]

Yeah a split injector O-ring would cause a boost leak, also check the FPR

[popdemonic]

Also do the same thing.mine got hit 1.7bar for 5secs and suddenly loss of 1Bar of boost.
The boost will sustain at 0.8bar.Let off gas and floor again boost hit 1.7 bar and do the same thing.
replaced WG,forge 007.it never fixed this issue.using the EBC to rule the N75 out.Set the boost to 1.35
bar.it never has any problems.but it seems I need 0.35 bar more of boost.

[avants2turbo]

fking boost leaks!
Boost tested the the system today, theres no leaks between the maf and tb, but theres an almighty leak sounds like its coming from the pcv area?! Injector seals arnt leaking, sprayed them with water/soap. There were oily bubbles coming from the cam cover rubber seal, firstly how would air get in there and would it cause boost leaks? How do i stop this?

[newsh]

Have you got the small hose to the PCV system disconnected and plugged at the MAF hose end when testing?

If not you might have blown a hole in one of the PCV pipes which are likely to be rotten, also you'll be pressurising the crankcase.

There's a little one way valve hidden in the pipes between the IM and PCV system, if this is broken or stuck open you will get boost escaping into the PCV pipes. If there's a hole in the PCV pipes somewhere you'll also get unmetered air being drawn in.

[avants2turbo]

Have you got the small hose to the PCV system disconnected and plugged at the MAF hose end when testing?

If not you might have blown a hole in one of the PCV pipes which are likely to be rotten, also you'll be pressurising the crankcase.

There's a little one way valve hidden in the pipes between the IM and PCV system, if this is broken or stuck open you will get boost escaping into the PCV pipes. If there's a hole in the PCV pipes somewhere you'll also get unmetered air being drawn in.

what small hose from the PCV system should i be plugging in to the MAF hose end, and where does it plug into?

PCV pipes were all off last week and cleaned, all in good health

where abouts is this one way valve ?

it does run lumpy as sin, so it would suggest that there is unmetered air getting in somewhere...