Recirculating wastegate/dumpvalve

[Fifeaudi]

Hi guys,

Recently change the air filters for the itg's

Out today for a blast and while lifting off the accelerator im hearing the dump valves or waste gates, really loud and never heard this before, anyone else hearing this, is it normal?

Air pressure is high today, is this a contributing factor?

Any comments are appreciated?

[Ungjaevel]

Are you talking about the old "pssss", like busses or trucks? That's a BOV (Blow off valve) in VTA mote (Vent to Atmosphere).
When it's in VTA, you would hear the psss... in recirculating mode... no.
Mines are certainly not in VTA mode, and there is no reason why any car would ever have it.. unless it's in a movie and it's "cool". (And it was cool 10 years ago..).

Wastegates drives the turbos, and have nothing to do with the psss sounds...

[Fifeaudi]

I know what they are, i just didnt think i should be hearing them on an rs6.

And they have never been cool in my opinion

Had it in at audi for paint on thurday aswell and now its doing this

Strange,

It doesnt sound like its recirculating into the system it does sound like its blowing off

[Ungjaevel]

You shouldn't be hearing it on RS6.

Sound from both or only 1 side? I'd look for any hose(s) off their nipples/connectors after the BOV.

[Fifeaudi]

Ive had the bonnet up and cant see anything loose, it sounds like it just the drivers side, but hard to tell, ive had the car since june and thats the first of me hearing it though

Head scratching time

Performance does seem to be ok though

[luffenham1]

Don't worry about it. Mine did the same when I fitted the filters. You could really hear it in second gear lift off as you start to build the speed.

I like the noise, well did before I sold the car

[Ungjaevel]

You could really hear it in second gear lift off as you start to build the speed.

Sounds to me like the spooling sound?

Spool (15 secs into it): http://www.youtube.com/watch?v=iLq65KBIw2o
BOV: http://www.youtube.com/watch?v=HblCEQXQ8Q4

Spooling sound is no problem, and you would expect a higher flowrate (and sound) after the filter change... what's why you did it, right!

Does the sound occurr when throttling or at gear change with high boost?

[Fifeaudi]

Yes can hear it spooling but the blowing off was the confusing bit.

I knew my b5 s4 had recirculating dump valves so was expecting same on my rs6

So just wasnt sure when i heard it

[Fifeaudi]

Spooling obviously when accelerating but blow off when come off throttle, not so much at gear change though,

[classba]

Hi guys,

Recently change the air filters for the itg's

Out today for a blast and while lifting off the accelerator im hearing the dump valves or waste gates, really loud and never heard this before, anyone else hearing this, is it normal?

Air pressure is high today, is this a contributing factor?

Any comments are appreciated?

I heard mine after cleaning the MRC filters only with the window down.

[Ungjaevel]

Spooling obviously when accelerating but blow off when come off throttle, not so much at gear change though,

Then I don't think it's the BOV. (The BOV prevents backflow of boost pressure into the compressor wheel (at wrong direction) when throttle is closed (gear change).)

If when coming off throttle, the throttle is actually still open and will close gradually. I don't know where any sudden loss of air pressure would come from here.
When/if you find out where it's coming from... I'd be interested. You always learn something new.

[Fifeaudi]

Sure, will keep you updated, it is the dump valve blow off valve its same noise,

But im coming right off the throttle, im guessing it fly by wire throttle any way so once you foot right off, the throttle will be shut

[Ungjaevel]

Will be interesting to hear the answer.

im guessing it fly by wire throttle any way so once you foot right off, the throttle will be shut

I'm quite sure it is, however even though the pedal isn't linked mechanically to the throttle, once you go off the pedal, the throttle is still open, so much as to feed the engine the air and the fuel needed according to rpm, while it's decreasing. (Not sure on the terms in english here: retardation or motor break?). So the boost that was spooled up will still be used, and therefore it should not go back and be discharged through the BOV.
In gear change; rpm quickly reduced from 6500 to 3000, air mass is reduced, and the boost will find the easiest way out; back - exiting through the BOV.

Getting late... have a good one.