Ultra aggrivated! My turbos can't be bad...

[alias747]

So I've made a thread about this not to long ago:

http://www.audizine.com/forum/showthread.php?t=229530

There is a guy that is wanting to buy/trade for my car and he wanted to get it checked out before buying. I told him about the boost leak and of course he could feel it was weak when he drove it. They brought it to a shop and they are had the car for a couple hours and couldn't figure it out. I'm not sure how well those guys knew this engine though. Then they took the car to Further Performance in Minneapolis, some of the Minnesota guys should know this place. Tristan over there looked at it but didn't have a whole lot of time to work on it. They tried replacing the DV's to no avail. So after running out of time to look at anything further both shops assumed that one of the turbos was bad...

Now, I don't think that it is a bad turbo, but I'm sure that it is something that isn't going to be cheap to fix. I've had this "boost leak" for the last 4 months at least. About 2 months ago I had my DP's off to get my clutch replaced and I felt both turbos and there was no play in them. So I don't really think that would be it since the issue has been the same since then.

When I drive, I hear a loud "whooshing"/air leaking noise from the right side of the car. It does not sound ANYTHING like any of the blown turbo noises that I've heard before in videos and such. And there is absolutely no white smoke from the exhaust. It just sounds like leaking air. I have pressure tested several times and I don't hear anything. I'm at my wit's end!

Is there any possibility that a wastegate could be stuck open? Or does that not happen on these turbos? If I can get a hold of a camera I will try to get the sound I hear recorded.

[S4 John]

did you pressure test it? did you check the intercooler hoses, tbb, & f-hose?

[exorcet]

a boost gauge will let you know if your wastegates are stuck open and you're overboosting. you have a boost gauge, right? right?

do you have a darintake? that can be your loud whoosing noise. Either way, with a boost leak for 4 months there is a possibility you could have damaged turbos from overboosting or working too hard to make requested boost.

only way you can confirm the boost leak is to pressure test, plain and simple. and get a boost gauge if you don't have one - with not one, but two turbos to go bad you really need to know what they are doing.

[alias747]

I said I have pressure tested several times and I hear no leaks. I just put new clamps over all the intercooler hose connections and tightened them down like nothing else, i wouldn't be surprised if I bent the piping tightening them!

TBB is silicone and I didn't hear anything from it pressure testing. F-hose is silicone as well and it doesn't sound like the air noise is coming from the front of the engine.

[AudiSportB5S4]

the wastegates sometimes do get stuck open....

have you pressure tested the wastegate lines? those sometimes tear?

[alias747]

a boost gauge will let you know if your wastegates are stuck open and you're overboosting. you have a boost gauge, right? right?

do you have a darintake? that can be your loud whoosing noise. Either way, with a boost leak for 4 months there is a possibility you could have damaged turbos from overboosting or working too hard to make requested boost.

only way you can confirm the boost leak is to pressure test, plain and simple. and get a boost gauge if you don't have one - with not one, but two turbos to go bad you really need to know what they are doing.

Yes I have a boost gauge and yes the boost is low and builds slow compared to what it should be. Ever since I heard the boost leak I've been driving the car like a grandma, I don't drive it during the week and when I do drive it I take it on highway trips to the twin cities, it sees minimal boost.

I pressure tested and nothing is showing up, I'm wanting to believe that it's something after the throttle body leaking and that's why I can't hear it during a pressure test.

[RolledMySTi]

You need to pressure test again. Listening for leaks only works on giant leaks. You need to get a spray bottle of soapy water and spray the hoses when you pressure test. Bubbles equal leaks and it's the only sure fire way to know if you have a leak somewhere. Take at least 15 minutes doing in and spraying away. If there is a leak you will find it. And as a bonus you will have a cleaner engine.

[JDM EJ1 95]

i dont think you have a leak if you already pressure tested everything.

[alias747]

the wastegates sometimes do get stuck open....

have you pressure tested the wastegate lines? those sometimes tear?

I haven't pressure tested the wastegate lines, I guess I don't even know how to go about doing that. I would def try it.

[alias747]

You need to pressure test again. Listening for leaks only works on giant leaks. You need to get a spray bottle of soapy water and spray the hoses when you pressure test. Bubbles equal leaks and it's the only sure fire way to know if you have a leak somewhere. Take at least 15 minutes doing in and spraying away. If there is a leak you will find it. And as a bonus you will have a cleaner engine.

Exactly, it def is a big leak though, that's why if it was on the intercooler hoses or anything before the throttle body I def would have heard it. The soappy water is a good idea though that maybe ill do sometime to find all the little spots, but right now I need this big "leak" fixed.

[alias747]

i dont think you have a leak if you already pressure tested everything.

I've pretty much concluded that too, it's either something really small and dumb that I'm overlooking (faulty n249, loose t-fitting near n75) or its something really bad like a stuck wastegate or cracked gasket to the turbo or something ridiculous that will make me have to pull the engine. :sigh:

[AudiSportB5S4]

there was a thread on how to test WG lines. do that for sure. also, could be the N75 as that is a boost actuator... do you have a buddy with a local S4 to see if you can swap N75s? in the meantime pressure test the WG lines

[gointoscott]

I still think you should try logging block 115 for actual boost and requested boost to see if that will help

you busy saturday morning? I can come over and help then. I'll bring my camera too.

[alias747]

there was a thread on how to test WG lines. do that for sure. also, could be the N75 as that is a boost actuator... do you have a buddy with a local S4 to see if you can swap N75s? in the meantime pressure test the WG lines

The N75 has to be fine, it was doing the same thing when I was running my MBC standalone a month ago. I just recently put the N75 back in standalone becuase I didn't want to be forcing boost.

Ill try to find that wastegate thread, thanks for the info.

[alias747]

I still think you should try logging block 115 for actual boost and requested boost to see if that will help

you busy saturday morning? I can come over and help then. I'll bring my camera too.

I'm glad your going to be in town this weekend man, we def got to meet up and we can look at it together too and try maybe doing the wastegate lines and the DV lines. Thanks!

[AudiSportB5S4]

here ya go !

http://www.audizine.com/forum/showth...ight=wastegate

[alias747]

here ya go !

http://www.audizine.com/forum/showth...ight=wastegate

That thread and especially that PDF is AWESOME! Thank you man, I will def try those lines. Thank you, thank you, thank you!

[JDM EJ1 95]

get a vac tester from autozone. unplug the vac hose from the n75 going to the wastegate.

stick the vac tester on the hose(making sure you have a tight seal)


pump the vac tester up to say like 30. and watch to see if its dropping at all over a minute or so.

if it is.. then you have a leak.. if not.. then y ou dont lol

[AudiSportB5S4]

That thread and especially that PDF is AWESOME! Thank you man, I will def try those lines. Thank you, thank you, thank you!

no problem

thats what were here for were all brothers with the same problems lol

[AudiSportB5S4]

get a vac tester from autozone. unplug the vac hose from the n75 going to the wastegate.

can you buy those ? is that cheaper than buying a compressor for everytime you have to P test ?

[exorcet]

yeah check the y/t fittings out at the wastegate lines -- those are prone to crack.

i also agree that you should pressure test and spray with soapy water - particularly in the area you think you hear the noise. i had a leak on my brake booster hose i couldn't hear, but bubbled nicely when sprayed.

[JDM EJ1 95]

can you buy those ? is that cheaper than buying a compressor for everytime you have to P test ?

you can actually rent a vac tester from autozone.

[alias747]

yeah check the y/t fittings out at the wastegate lines -- those are prone to crack.

i also agree that you should pressure test and spray with soapy water - particularly in the area you think you hear the noise. i had a leak on my brake booster hose i couldn't hear, but bubbled nicely when sprayed.

Sorry for my ignorance but where is the brake booster and what does it look like? What does it do exactly? Thanks!

[exorcet]

Sorry for my ignorance but where is the brake booster and what does it look like? What does it do exactly? Thanks!

it is the black hard plastic line you see going into your firewall from the engine compartment on the driver side. it has 3 attachment points - manifold, under accordian hose and through firewall to brake booster.

here are some pics - common leak place is the "T" of the hose where the goop is in the last picture. that's where mine was leaking from, too.

http://forums.audiworld.com/s4/msgs/2771703.phtml


it probably wouldn't make a huge leak sound unless maybe it was unplugged from your accordian hose? but your brakes would feel like they were locking up every time you got on the brakes quickly/with force if that were the case.

[AudiSportB5S4]

it has 3 attachment points - manifold, under accordian hose

2000's do not have the connection @ the MAF only 2001s and upp .

[exorcet]

2000's do not have the connection @ the MAF only 2001s and upp .

ah I learn something new every day!

[S4 in_lowplaces]

Pressure testing only confirms leaks pre turbo. Post turbo dosent get pressurized. You prob have a leaky IC hose. GL.

[alias747]

Pressure testing only confirms leaks pre turbo. Post turbo dosent get pressurized. You prob have a leaky IC hose. GL.

I think you have that wrong... It most definitely pressurizes the intercooler hoses after the turbos. I have found leaks in my intercooler hoses that way. Heck I accidentally forgot to tighten an intercooler hose and it popped off during the pressure test! Do you mean it doesn't pressurize post throttle body?

[S4_NE]

what Ic's do you have? if stock the end tanks could be leaking? good luck

[alias747]

what Ic's do you have? if stock the end tanks could be leaking? good luck

Not stock, I got a front mount. If it was leaking I would hear it during the pressure test wouldn't I?

[S4_NE]

I would think so you should here it

[S4-Casa]

You would hear it but a trick that might help..
get a plain jane piece of paper..and move it around the ends of the hoses and the intercooler itself you will see the paper move in the opposite direction and you can always use that method to find the leak.. I found one on a front mount where the power steering line was rubbing against it.