[M3coco]

I have the valves open all the time (with a valve controller). ASD is completely coded off with bimmercode. There is still a sound difference on the outside 100% when the button is on vs off, with valves permanently open. There is clearly more to it then just pumping in noise and valves.

[hinckley]

I do not believe ASD is ever turned completely off unless it's been coded that way. As an earlier poster stated, BMW wants us to believe that the natural exhaust sound and ASD are the same thing. They barely acknowledge ASD's existence. So if the natural exhaust note is reduced with partially or fully closed flaps, ASD's sound is reduced as well. But there's never no natural exhaust sound, so there's never no ASD exhaust sound (unless it's been coded off).

[Kevin234]

Ahhh dammit!
Instead of ASD off, I was going to say ASD kinda disabled, and I forgot...

[PVC]

Originally Posted by M3coco

I have the valves open all the time (with a valve controller). ASD is completely coded off with bimmercode. There is still a sound difference on the outside 100% when the button is on vs off, with valves permanently open. There is clearly more to it then just pumping in noise and valves.

Is it a noticeable difference? Have you tried to measure the decibels (maybe using a phone app)?

[TopJimmy]

I have noticed that even with ASD set to Off using BM3 there is still burbles in sport modes when the exhaust sound button is on. In BM3 I also have burbles set to Off and am running the OTS CSL tune.

[ChrisM4]

The sound control button changes the exhaust flap operation, quiets ASD and also changes burbles. (Reduces them greatly)

[M3coco]

Originally Posted by PVC

Is it a noticeable difference? Have you tried to measure the decibels (maybe using a phone app)?

I think so. It's much more burbley when you let off the throttle when you have the button on, vs off.

[jummo]

I'm probably the only one who doesn't find the fake sound objectionable.
If I'm just driving, I leave asd on. But if I am listening to music, I turn it off.
The stereo sounds much better with it turned of, at least to my ear.

[Mike02z]

Once ASD is coded out you will still get burbles and crackling when removing your foot from the gas. I was looking for something I read a few years ago about why. This is part of the article I found…credit to Justin Creamer, Mechanical Enginner…

“The pipe size of an exhaust exhaust must be optimized for a specific flow rate. This is usually at max RPM and max throttle for high-performance cars. But at idle, the size of the exhaust system is much too large to maintain a constant velocity of the gas for its entire length. This gives you a burbling sound as the exhaust stream has a push-pull effect: some exhaust is pushing out with flow of the engine, some is pulling back as it cools and contracts.

Crackling is the same concept, except more extreme. It happens when you lift the throttle at mid and high RPMs. You have hotter, high velocity exhaust, suddenly followed by cooler, lower velocity gas. The pressure difference between the two crackles while the they equalize. It's a sound that never fails to put a smile on my face!”

[Berzerker]

Originally Posted by Mike02z

Once ASD is coded out you will still get burbles and crackling when removing your foot from the gas. I was looking for something I read a few years ago about why. This is part of the article I found…credit to Justin Creamer, Mechanical Enginner…

“The pipe size of an exhaust exhaust must be optimized for a specific flow rate. This is usually at max RPM and max throttle for high-performance cars. But at idle, the size of the exhaust system is much too large to maintain a constant velocity of the gas for its entire length. This gives you a burbling sound as the exhaust stream has a push-pull effect: some exhaust is pushing out with flow of the engine, some is pulling back as it cools and contracts.

Crackling is the same concept, except more extreme. It happens when you lift the throttle at mid and high RPMs. You have hotter, high velocity exhaust, suddenly followed by cooler, lower velocity gas. The pressure difference between the two crackles while the they equalize. It's a sound that never fails to put a smile on my face!”

Except...you can turn them off if you press the center console button :P

[TomGorka]

When I was at the BMW training center the BMW trainer said , that only in Track mode the valves are fully open - because of some noise/volume standards etc

[Prossx]

Aren’t Euro noise standards way stricter than US? And BMW designs to that?

[Salex123]

Originally Posted by Kevin234

Good info here. Think I finally have a handle on how this thing works.
Question - I assume the "M Sound On/Off" button in the 2023 M3s is the same as "ASD On/Off" button being discussed here?

To summarize (I tried uploading a table to make it easier, but didn't work ):

ASD Button On (same as M Sound On?)
Comfort Mode: ASD On, Valves Closed
Sport Mode: ASD On, Valves Open
Sport + Mode: ASD On, Valves Open

ASD Button Off (same as M Sound Off?)
Comfort Mode: ASD Off, Valves Closed
Sport Mode: ASD Off, Valves Closed
Sport + Mode: ASD Off, Valves Closed

So basically, there is no option to have the exhaust valves open and the fake speaker sound off at the same time, and that's why we need Bimmer Code, correct?

Just to clarify is that engine in sport and comfort or what setting has to be in sport exactly?

[kgelfen360]

Originally Posted by Prossx

Aren’t Euro noise standards way stricter than US? And BMW designs to that?

But how come Porsche doesn’t mind EU sound laws?

[Scott Z]

On one of my previous M3’s there was an easy way to disconnect a wire or two (perhaps it was a small wiring harness) in the trunk to kill the fake engine noise piped through the speakers.

Is there no such option now?

I’d like the physical exhaust valves open when called for but I hate the fake interior audio.

[christianb5s4]

Originally Posted by Scott Z

On one of my previous M3’s there was an easy way to disconnect a wire or two (perhaps it was a small wiring harness) in the trunk to kill the fake engine noise piped through the speakers.

Is there no such option now?

I’d like the physical exhaust valves open when called for but I hate the fake interior audio.

At least thus far, there's no easy way to do that like pulling fuses on prior generations.

[Mapper]

Originally Posted by Berzerker

Except...you can turn them off if you press the center console button :P

Which alters timing , AF and valvetrain timing on throttle lift or shift.

[biggripper]

I can’t tell you exactly what the button is fully designed to do but I can tell you my experience with my current setup which is:
1) ASD coded off via bimmercode
2) valves full open with Dahler controller
3) MAD mid pipe

I went through several incremental stages of experimenting with this exhaust system. I started out with the Dahler controller so that I could have full control of the flaps. Then I moved to coding ASD fully off with bimmer code — which when done correctly is pretty obvious because the exhaust is significantly less prominent even when the valves are fully opened with the Dahler unit. Those changes were subtle enough that I was still unable to fully grasp what the hell the button was doing.

Once I installed my MAD mid pipe, the effects of the button were easier to observe and, therefore, much more clear. With a mid pipe, valve controller, and ASD coded off, it is now clear that the button only acts as a toggle switch for burbles.

ASD button on = lots of burbles.
ASD button off = zero burbles.

Personally I am unable to perceive any difference in volume.

[Berzerker]

Originally Posted by Mapper

Which alters timing , AF and valvetrain timing on throttle lift or shift.

I'd be inclined to ask for some documentation on where that's detailed

[FloridaM5]

Originally Posted by biggripper

I can’t tell you exactly what the button is fully designed to do but I can tell you my experience with my current setup which is:
1) ASD coded off via bimmercode
2) valves full open with Dahler controller
3) MAD mid pipe

I went through several incremental stages of experimenting with this exhaust system. I started out with the Dahler controller so that I could have full control of the flaps. Then I moved to coding ASD fully off with bimmer code — which when done correctly is pretty obvious because the exhaust is significantly less prominent even when the valves are fully opened with the Dahler unit. Those changes were subtle enough that I was still unable to fully grasp what the hell the button was doing.

Once I installed my MAD mid pipe, the effects of the button were easier to observe and, therefore, much more clear. With a mid pipe, valve controller, and ASD coded off, it is now clear that the button only acts as a toggle switch for burbles.

ASD button on = lots of burbles.
ASD button off = zero burbles.

Personally I am unable to perceive any difference in volume.

Yes, this 100%. Same here.

[G80_Bob]

Originally Posted by FloridaM5

Yes, this 100%. Same here.

I would disagree, I have MAD Downpipes, R44 exhaust and ASD codes off. The ASD switch in Sport or Sport Plus mode does add and remove burbles, but the volume of the exhaust is very different when not at WOT.

[Berzerker]

Originally Posted by G80_Bob

I would disagree, I have MAD Downpipes, R44 exhaust and ASD codes off. The ASD switch in Sport or Sport Plus mode does add and remove burbles, but the volume of the exhaust is very different when not at WOT.

Then you don't have ASD fully decoded.

The button does absolutely nothing if you do, it just controls engine timing to add/remove burbles.