Boost leak help -11 WRX

[scx89]

Mods are

Catback
COBB OTS stage 1
Boost gauge
Oil Pressure gauge

I was hitting boost on a fwy on ramp and I started noticing this weird noise - similar to a failed silent fart.

I just installed the defi boost gauge about a week ago and flashed to stage 1.
(was previously stage 2 w/DP but took that off)

Where does that boost leak sound like it's coming from? I hear it on the left front driver side - so I imagine it's the T connector. I have the T connected mounted about 2.5 inches after the BPV -> T --< Sender & whatever else it connects to lol. I checked the T connector today and it looks okay to me, I took off the crappy zip ties on the tubes and replaced it with 18lb tensile str zip ties but I'm still getting the noise.

Here's a video

2011 wrx boost leak? - YouTube

2011 wrx boost leak? - YouTube

I don't think it's the TB --> intercooler because I've had it on stage 2 before and it was all good at 17 psi. I'm only on 15psi w/OTS stg 1

If you look at the video, it rises up to almost 15, makes the fart, then drops to 10 and rises again, and farts and drops.

Any input is well appreciated..

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[arrowscooby]

check the bpv gasket, or check all your hoses again.

[stanrc]

Have you messed with the TMIC at all? Check the throttle body hose, each side has a rubber piece that is known to wear. My car was making that noise and this was what mine looked like:



Just take the pieces off each end of the throttle body hose and put it all back together nice and tight.

[scx89]

awesome picture
Throttle body hose is the thick hoses that comes out of the intercooler right?
I just take it off and put it back together? o.0
Do I have to take off the intercooler to access the hoses?

[stanrc]

Yes, it is the one that connects on the driver side. You will most likely have to take the TMIC off to get to it, and unfortunately because of the position you can't really confirm if thats the problem until you take it off. But if its like me (and a few others on here) once you unbolt the TMIC, it will just slide right off because those rubber things have come lose or ripped.

If you have the stock TMIC, it should only take 30-45 minutes, and even thats being liberal with time. Take the intercooler off, you will see the throttle body hose, each end has the worm clamp and the rubber piece, just take the rubber piece out, then put it back together.

[scx89]

The throttle body rubber hose connector was loose! just like you said stanrc!
I have a couple concluding questions at the end though

For those with a similar noise here are some pics for reference
When I took off the intercooler the rubber connector was stuck on the intercooler and I can also see the side of the throttle body hose coming off


I could tell from the white gooey looking thing on the TB hose


intercooler removal was easy - take off bracket bolts with 12mm and bpv with 11 or 10 mm i forgot. There werent any gaskets on the turbo->IC or IC->BPV so nothing to worry about there. Then you just yank it toward passenger side and it should come right out.


The End
I saw some oil where the BPV opening to the IC opening and also inside the TB hose






should i be concerned or is that normal just to grease stuff up?

[stanrc]

Glad that was the fix and great pictures. As for the oil, that is the usual blow by from these engines. That shouldn't be anything to worry about.

[matigas_TT]

Hmmmm same problem im having...

[xluben]

These are good pictures and a very common problem. Even at stock boost this can occur, but any increase in boost makes it much more likely. A bit of oil in these components is normal. I wouldn't worry about it, but maybe check it once in a while because that does look like a somewhat decent amount.

EVERY 08+ WRX should remove those rubber end caps from BOTH ends of the throttle body hose. You should also add a zip to to the vacuum line that goes from the top of the BPV to the back of the intake manifold. The nipple on the intake manifold does not have a barb and can easily slide off.

[CO11WRX]

Originally Posted by xluben

These are good pictures and a very common problem. Even at stock boost this can occur, but any increase in boost makes it much more likely. A bit of oil in these components is normal. I wouldn't worry about it, but maybe check it once in a while because that does look like a somewhat decent amount.

EVERY 08+ WRX should remove those rubber end caps from BOTH ends of the throttle body hose. You should also add a zip to to the vacuum line that goes from the top of the BPV to the back of the intake manifold. The nipple on the intake manifold does not have a barb and can easily slide off.

I wonder when Subaru will finally make a production change to rectify this issue. It seems there are three common problems people have when increasing boost (they can even occur on stock cars as you noted)
1. Bypass Valve leaking
2. Plastic end tanks separating on the stock TMIC
3. This problem (throttle body/IC hose popping off)

Fortunately the TB/IC thing seems to be an easy fix. I will most likely follow your advice and remove those POS end caps. I will probably invest in some t-bolt clamps as well.

[scx89]

Originally Posted by xluben

These are good pictures and a very common problem. Even at stock boost this can occur, but any increase in boost makes it much more likely. A bit of oil in these components is normal. I wouldn't worry about it, but maybe check it once in a while because that does look like a somewhat decent amount.

EVERY 08+ WRX should remove those rubber end caps from BOTH ends of the throttle body hose. You should also add a zip to to the vacuum line that goes from the top of the BPV to the back of the intake manifold. The nipple on the intake manifold does not have a barb and can easily slide off.

What exactly is the oil from? I've read that it's blow by and it's a result from the ringlands seals not being perfect and oil slipping past them. Shouldn't it be no oil at all? I need to find a good read on this

[xluben]

Originally Posted by CO11WRX

I wonder when Subaru will finally make a production change to rectify this issue. It seems there are three common problems people have when increasing boost (they can even occur on stock cars as you noted)
1. Bypass Valve leaking
2. Plastic end tanks separating on the stock TMIC
3. This problem (throttle body/IC hose popping off)

Fortunately the TB/IC thing seems to be an easy fix. I will most likely follow your advice and remove those POS end caps. I will probably invest in some t-bolt clamps as well.

That's a good plan.

Those are all common.

Also the hose that goes from the top of the BPV to the back of the intake manifold can pop off the intake manifold. Needs a zip tie to hold it on. if this pops off it causes a pretty bad boost leak. I don't see this one as much on stock cars. Usually higher boost (20+ psi).

Originally Posted by scx89

What exactly is the oil from? I've read that it's blow by and it's a result from the ringlands seals not being perfect and oil slipping past them. Shouldn't it be no oil at all? I need to find a good read on this

It's blow by. Some cars have more than others.

[Tripintaz]

90% of these complaints are due to the Throttle Body to Intercooler hose. The OEM one is crap and breaks open over stock boost levels. I think Subaru did it on purpose.

[GT3782]

Have you thought about installing an oil ketch can?

[scx89]

Originally Posted by GT3782

Have you thought about installing an oil ketch can?

Yeah, i was wondering whether to get a catch can or air oil seperator. They look like a pain to find a place to mount them