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Old 04-19-2002, 05:11 PM   #1
dyswtric27
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Member#: 404
Join Date: Oct 1999
Location: socal
Vehicle:
2000 Audi S4
endless.night

Default Loosing Boost - Loud howling

Now my car has been running fine for about 2-3 weeks with the turbo kit. On the 5 hour ride from Ithaca to Baltimore the car would start to not build boost and would begin to kinda howl. I could shake the car a little by blipping the throttle and get it to not whine and build boost again. This continued for about 30 mins, increasingly getting worse, to the point where i could no longer build boost at all, just howling.

I pulled over, tightened everything up and i could again build boost with intermittant howls. Its about a week later, and i have tried everything to get rid of this. Basically I can build boost in 1st and 2nd, then when i let off the gas in 2nd the howl and the BOV shoot at the same time. When i gas in 3rd there is the whine (howl) and no boost. I can kinda shake the car a little and begin to build boost again. Once the boost gets to about 4-5 psi the howl takes over and i lose all boost.

Now to me this sounds like a leak, but is extremely loud, like you can actually hear the fan in the turbo, so im not really sure. I have found a small tear in the silicon hose that connects the throttle body and IC. It extended halfway down the hose and is cuts into the hose 1/2 way (all the way through the red on the hose). Now this could very well be the culprit, but would it create such a loud howl? Any other suggestions?

Jason
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Old 04-19-2002, 05:22 PM   #2
Jewbaru
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Location: "Teh Hebro Town"
Vehicle:
2013 Impreza WRX
WRB

Default

you're BOV is proably loose. Tighten the bolts down some more, and make sure the flange isn't warped. Check all the vacuum hoses, and clamps as well.

Also, yes the tear can cause a howl. I forgot to tighten a hose clamp (I know, I know) by the turbo, and when the car built boost, it howled REALLY loudly. Put duct tape over the hose, and see if it stops. Duct tape should hold untill you can get a new hose.
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Old 04-19-2002, 05:25 PM   #3
RallyNavvie
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Location: Minnesotan in Texas
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2008 Spec B
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How long is the hose connecting the TB and the IC that you say this cut is in? My intercooler almost rides right on the TB the hose is so short. If the cut is all the way through the hose then... duh!

You should replace that ASAP on the principle of the thing, and also to eliminate that as the source of the problem. It would make sense that the tear only comes open under boost. It would also make sense that the tear would come open when you let off the throttle because there is suddenly a lot of pressure on the TB and the IC as the butterfly closes, that's the pressure the BOV releases. Or in your case your hillbilly BOV (the cut)

On the larger scale, if that cut is letting any air in when the engine is not running at boost (vacuum) then you may very likely be sucking in unfiltered air right into the engine. Not only that but it's likely right under the hood scoop and getting lots of debris flowing past it. Get that replaced right away and don't drive through lots of dust.

~Garrett
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Old 04-19-2002, 05:27 PM   #4
dyswtric27
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endless.night

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Yeah, my IC - TB hose is extremely short. Only like 1.5-2 inches long. And the slit is at least an inch if not more of that. I will try the duct tape method and see if it helps. Thanks.

Jason
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Old 04-19-2002, 06:28 PM   #5
Graham
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2001 2.5 RS Turbo
257/FMIC/T3-T04S

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I also experienced the same problem. On boost, or near it, my BOV was separating from the intercooler and letting air out. I couldn't figure it out for about a week. A friend of mine had me rev the engine and found that the BOV was separating on let off. It make a weird sound kind of like a howl.

Oh, I forgot to tighten the BOV down and consequently the bottom screw of the BOV fell off!

Graham
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Old 04-19-2002, 09:56 PM   #6
dyswtric27
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2000 Audi S4
endless.night

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Well i may have found the problem. I duct taped the IC-TB silicon hose on as good as i could then threw the clamps over that. The bowl was gone for a good 5 mins with solid boost up to 5 psi. Then when i let off the gas in 3rd at 5 psi, the BOV went and so did that howl again. So i assume the leak busted through the tape. Now its off and on like before, but at least i can run somewhat.

I am getting a new silicon hose early next week which should clear it all up.
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