# Exhaust flap - permanently open?



## Domz (Aug 22, 2016)

Hey Guys,

On my S-Line I found that whilst I have a flap and the electronic module bolted on, it doesn't seem to ever close on any drive modes?
Do you guys in the UK have the same? It is possible does the flap always open when stationary?

Cheers


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## noname (Aug 20, 2015)

its working is odd enough...it is often open, it closes in R and as soon as you drive but change its position depending from the revs


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## Matrix (Apr 11, 2016)

Does it also change position during cold start as I've noticed the engine note change after a minute or so from start up?


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## Toshiba (Jul 8, 2004)

i knew a girl with the same problem.. :twisted: (said Mr Trump)


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## Alan Sl (Nov 11, 2009)

Excuse my ignorance but what is the purpose of the exhaust flap?


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## noname (Aug 20, 2015)

Since we have a turbo, there is the need to keep the exhaust in pressure at low revs to prevent the turbo lag.
It allows to make a bigger exhaust avoiding the gases going out from the turbo too fast
With keeping it always open, I've noticed a bit delay but always a better sound.
I'm planning to activate it again..just for fun!


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## Toshiba (Jul 8, 2004)

The reason they exist is for more than one single reason. In acoustical optimisation, exhaust noises are influenced by adapting the volumes and pipe lengths of silencers so this is what gives the different sounds in the different modes.
For emission control, exhaust gas flaps are used to divert the exhaust gas flow.
By varying the exhaust gas back pressure, the efficiency can be improved in certain characteristic areas.


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## Alan Sl (Nov 11, 2009)

Toshiba said:


> The reason they exist is for more than one single reason. In acoustical optimisation, exhaust noises are influenced by adapting the volumes and pipe lengths of silencers so this is what gives the different sounds in the different modes.
> For emission control, exhaust gas flaps are used to divert the exhaust gas flow.
> By varying the exhaust gas back pressure, the efficiency can be improved in certain characteristic areas.


Can you alter the flap within the cabin and increase the exhaust noise (other that via the dynamic option). In our roadster I can hardly hear any rasping noise other than the odd blip from the exhaust or I am expecting too much? Our car is a 2.0 Quattro stronic.


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## Toshiba (Jul 8, 2004)

Its linked to the modes on ADS, but thats all.
If you use individual mode you have control the noise a little.

Noise is a personal preference, what some say is low, others will say is too loud..
TT uses a resonator to create a manufactured noise.


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## thanasis.mpougon (Sep 28, 2015)

Mine is always open(saw the coding through VCDS)If i close it I can expect less turbo lag(not by far but will it be noticable)

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## noname (Aug 20, 2015)

I presume, the bit on the vcds, doesn't work as permanent solution,but seems to keep the valve much more open than the original set anyway!
The big difference in sound and turbo lag, is noticeable only if you disconnect electrically the valve.


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## thanasis.mpougon (Sep 28, 2015)

Ok thanks manu

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## CiLA (Oct 31, 2015)

My friend upgraded my exhaust little -
Sound is grest ...


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## noname (Aug 20, 2015)

That was my idea..an hidden exhaust into the original one!! No risk for the police


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## 4433allanr (Mar 11, 2016)

Toshiba said:


> i knew a girl with the same problem.. :twisted: (said Mr Trump)


Sniff, sniff!


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## 4433allanr (Mar 11, 2016)

Never good to have your flaps permanently open!


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## CiLA (Oct 31, 2015)

you write one reason why not ...


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## noname (Aug 20, 2015)

just read an article where the valve working is explained..
from 1st to 4th gear, the valve is open from min revs to 1800 then it closes until 3500 where it opens again until the red zone
5ft and 6th gears the valve is always open.

anyway, some cars have the flap installed bit checked and other don't, but seems it doesn't affect the system at all, to have more sound, just disconnect the valve power.


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