little trick

[kaisersolsay]

Na same shape as the above pics Bling.

I think that the originals must have been damaged (speed hump perhaps) and replaced with non genuine units. Will this have any effect on the performance?

[BlingBling]

I would imagine nothing noticeable. The valves were/are mainly for cabin noise. quite below certain revs. Once above a certain rev then the valves open and the zorts start to sound like a tenor opera singer.

[kaisersolsay]

Hi,

See pics below

[kaisersolsay]

another pic

[nidfix]

I would imagine nothing noticeable. The valves were/are mainly for cabin noise. quite below certain revs. Once above a certain rev then the valves open and the zorts start to sound like a tenor opera singer.

The valve is closed after 1700 not open, to limit high rev noise

[tuscy]

Not sure about that statement, this is from the RS4 thread:


Non Sport mode:
exhaust flaps stay shut until 5,000k rpm in 1st, 2nd, 3rd gear.
exhaust flaps stay shut until 4,500k rpm in 4th, 5th, 6st gear.
throttle 50-60 % open till 5,500 rpm in 1st, 2nd, 3rd
throttle 100% open 0-8,250 rpm in 4th, 5th, 6th

Sport mode:
exhaust flaps open at idling 760rpm
exhaust flaps shut from 1,000k rpm until 3,700k rpm in 1st, 2nd, 3rd
exhaust flaps open ALL the time from 0-8250rpm in 4th, 5th, 6st gear.
throttle 50-60 % open till 5,500 rpm in 1st, 2nd, 3rd
throttle 100% open 0-8,250 rpm in 4th, 5th, 6th

Now I know that the S4 doesn't have a sport mode but the mapping is probably similar to the non-sport mode on the RS4. You definitely get more noise above 4K ish. Might give it a whirl when I get time.

[nidfix]

Not sure about that statement, this is from the RS4 thread:


Non Sport mode:
exhaust flaps stay shut until 5,000k rpm in 1st, 2nd, 3rd gear.
exhaust flaps stay shut until 4,500k rpm in 4th, 5th, 6st gear.
throttle 50-60 % open till 5,500 rpm in 1st, 2nd, 3rd
throttle 100% open 0-8,250 rpm in 4th, 5th, 6th

Sport mode:
exhaust flaps open at idling 760rpm
exhaust flaps shut from 1,000k rpm until 3,700k rpm in 1st, 2nd, 3rd
exhaust flaps open ALL the time from 0-8250rpm in 4th, 5th, 6st gear.
throttle 50-60 % open till 5,500 rpm in 1st, 2nd, 3rd
throttle 100% open 0-8,250 rpm in 4th, 5th, 6th

Now I know that the S4 doesn't have a sport mode but the mapping is probably similar to the non-sport mode on the RS4. You definitely get more noise above 4K ish. Might give it a whirl when I get time.

I answered based on the drawing.
In addition, I found that explanation on various magazines.

Anyway either for high revs or low revs it is better not to have it at all

[tuscy]

Yeah, I didn't think the diagram told the full story though, there's got to be a similar mapping to the RS4. The valve must open up again at higher revs otherwise it's only open between tickover and 1700rpm - which seems mad!

How much driving is done between these limits - idling, pulling away ... and that's about it!

Anyway, I agree they should be open all the time.

[ste4ie]

Somthing else to check if your valves are working, with engine off i have one valve open and one closed !!!!!, you can see by looking inside the exhaust with a light.
In unmodified form should they be open or closed with engine off

I have a manual B6 by the way,

Cheers Steve

[tuscy]

You have a stuck valve! They should both be open with the engine off - I checked mine this morning just to be sure.

[ste4ie]

Thanks for that, at least i know which one is faulty now. It does seem strange that they close above 1700rpm, as posted above, to reduce noise !!!!, what were Audi thinking of ?.

[chunky79]

I did this on my B6 S4 manual yesterday. Not really noticed much in performance but it's seems to have a little bit more of a rumble when crusing

[nidfix]

I did this on my B6 S4 manual yesterday. Not really noticed much in performance but it's seems to have a little bit more of a rumble when crusing

Depends on which version of the software you have. On the latest ones they stayed open so there is nothing to get

[wolf02]

Made this change to mine a few weeks back - B6 (03)
Took a few days to get any noticable improvement but after the ECU updated its definately better.
Pulls more from low revs, nicer sound, much more consistant, better feel to the car.
Definately recommended to all ! Took me 10 mins to do !!

One concern, is it likely to affect the emissions on the car ? should I put it back for the MOT ?? is there any likely long term damage (without getting an ECU remap). I had an FTO before this and you could make huge changes and the ECU simply adjusted accordingly.
Does the S4 have a similar "intelligent" ECU or is it a standard map that HAS to be changed every mod ??

[nidfix]

One concern, is it likely to affect the emissions on the car ? should I put it back for the MOT ?? is there any likely long term damage (without getting an ECU remap). I had an FTO before this and you could make huge changes and the ECU simply adjusted accordingly.
Does the S4 have a similar "intelligent" ECU or is it a standard map that HAS to be changed every mod ??

It will not affect the emissions of the car. It was done for the noise.
You don't need to put back for MOT. The ECU remap simply includes that change. So even if you let the pipes in, the valves stay open. In fact from what I have noticed most of the good aftermarket exhausts (like SuperSprint for example) do not include any valve...
S4 ECU has a window for adjustment like any modern ECU. The main difference with tuning ECU is that most of the window is allocated to handle bad conditions (low octane fuel for example).


Enjoy !