[Ron Jeffries]

Originally Posted by VPB74

The ASD unit is located in the trunk next to the stereo amp. You can't just unplug the ASD unit since it's tied into the stereo and other electronic systems of the car, so you have to bypass it. A bypass kit/harness consists of a specially wired plug that replaces (i.e., bypasses) the ASD unit. They are available from a few outfits such as Bimmertech.

Ah. I just coded it off. Seemed to work fine.

[RvR]

But I have the same year and model car as the OP, and putting the bypass harness in made a BIG difference. Much quieter, and no fake sound. Glad to have ASD gone.

Before I put the harness in, I wasn't sure ASD was there, but boy with the harness in, I realize there was a lot of fake sound via the speakers.

It should have been a switchable option in the iDrive to me, but BMW felt otherwise.

[CP911]

Originally Posted by RvR

But I have the same year and model car as the OP, and putting the bypass harness in made a BIG difference. Much quieter, and no fake sound. Glad to have ASD gone.

Before I put the harness in, I wasn't sure ASD was there, but boy with the harness in, I realize there was a lot of fake sound via the speakers.

It should have been a switchable option in the iDrive to me, but BMW felt otherwise.

6-speed or automatic?

[kivyee]

Originally Posted by morphomeman

When you start the car in the morning, only one exhaust pipe is open and it sounds louder. it also sounds louder because the garage acts as an amplifier and resonator. Once you get out of the garage, you lose the amplification/resonation and after a minute or two the second pipe kicks in. So voilà, your car is much quieter.
Happens every morning!

What you are describing is cold start. Yes...It's loud. Amplification due to the garage is only a part of it.

[Ron Jeffries]

My 2018 is loud on its startup idle, even outside, and quiets down as soon as I touch the gas or put it in gear. The 2018 MPE doesn't have the muffler flap.

[RvR]

Car is a 6 speed. I do not know why 8AT would be any different, though.

When I enquired at BMW Weld ED, my rep told me, "ASD is not on in Comfort mode, and in re turning it off, 'Ask your dealer.'"

She was misinformed, it's definitely ON in Comfort mode, and the dealer told me they can turn it off once, but it wouldn't stay off.

So installing the harness fixes the issue.

[moldcad]

Originally Posted by matthibodeau

The ASD system is very noticeable when you code it off..
I recently did this with bimmercode and do not regret it at all, music sounds better and you can actually hear the real engine/exhaust.

Which model and year? I'm thinking of coding ASD off in my 2015 M235i coupe, as I simply don't like how it sounds inside. I'd even say that at high speed on motorway, there is some droning.

But the drone might come from the exhaust and not the ASD, so shutting it off will not help...

Piotr

[35mmSummicron]

2018 m240 cabrio here with MPE port installed. I found when coding ASD through Esys, the difference was night and day. When I first got my F23 I thought the Exhaust was loud all around, now I hear it only from the back-where it should be.

[RoundelM3]

Originally Posted by morphomeman

When you start the car in the morning, only one exhaust pipe is open and it sounds louder. it also sounds louder because the garage acts as an amplifier and resonator. Once you get out of the garage, you lose the amplification/resonation and after a minute or two the second pipe kicks in. So voilà, your car is much quieter.
Happens every morning!

This is inaccurate. The reason the car is louder during cold start is due to the turbo wastegate being completely open during fast idle, bypassing the turbo and its muffling effect. The exhaust flap stays closed during this time and continues to stay closed until the DME detects aggressive throttle position or sport/sport+ mode. Opening the flap does not make the exhaust quieter. Once the wastegate closes and the idle returns to normal, the exhaust quiets down.