[Kief]

I apologize if this has already been discussed, but it appears the M40i exhaust upon start up only opens the right/passenger-side exhaust valve and the left/driver-side remains closed--presumably until a set operating temperature is achieved, or during heavy loads when driving if still cold?

Has anyone looked to see if there is a vacuum line that can be zip-tied or unplugged (throw a code?) in order to keep both valves open at all times? I remember doing this with my previous E9x 335i cars. Our current X5 with M Performance Exhaust is open on both sides upon start up and sounds great.

[voyagergab]

May I ask what would be the value of changing this behaviour?

My E90 335i also started like this, my F10 535i didn't I guess because it had an aftermarket quad pipe exhaust.

[Kief]

Originally Posted by voyagergab

May I ask what would be the value of changing this behaviour?

My E90 335i also started like this, my F10 535i didn't I guess because it had an aftermarket quad pipe exhaust.

Strictly for sound

[BobsM3Coupe]

Originally Posted by Kief

I apologize if this has already been discussed, but it appears the M40i exhaust upon start up only opens the right/passenger-side exhaust valve and the left/driver-side remains closed--presumably until a set operating temperature is achieved, or during heavy loads when driving if still cold?

Has anyone looked to see if there is a vacuum line that can be zip-tied or unplugged (throw a code?) in order to keep both valves open at all times? I remember doing this with my previous E9x 335i cars. Our current X5 with M Performance Exhaust is open on both sides upon start up and sounds great.

It's electrically operated. It's been done this way (for BMW anyway) for years to help the cats warm up faster. On a cold start, it does make the vehicle look like it has a fake dual exhaust system.

[Kief]

Anyone play around with their M40i exhaust yet?

I don't know why, but it bothers me about both exhausts not being open during cold startups and only the passenger side exhaust emanating smoke--looks like the left side is fake or broken. Plus, the added sound is always a good thing IMHO--maybe not for the neighbors, but anything is quieter than my Jag F-Type Coupe R!

Is this how it is with the current X4 M40i folks as well??
My wife's previous X5 had the M Performance Exhaust and both pipes were open at startup.

[Tjalle]

You are on tricky ground.

I bought my M Performance exhaust, because I did not like dual one-side-only exhausts.
X4 MY 15. See pic. It is is developed and produced by Red Arch Engineering and Manufacturing in the UK. System has two modes: Sport and Track - operated by Bluetooth and a pushbutton. Sound at start-up is similar to OP - on Sport

Tricky thing is that interior sound is marginally better/ higher on Track than original. Countrary to X4 M40i, with which I have done a test drive. My conclusion was that X4 M40i has a fake interior sound - which upset the X4 M40i community.

[cthomp88]

Originally Posted by Kief

Strictly for sound

I put mine in sport, to open the flap, and then there’s a plug on the left side exhaust. I unplugged that and taped/covered it up. That has kept the flap open permanently. My BF did the same thing on his M3.

[Kief]

Originally Posted by cthomp88

I put mine in sport, to open the flap, and then there’s a plug on the left side exhaust. I unplugged that and taped/covered it up. That has kept the flap open permanently. My BF did the same thing on his M3.

Thanks.
I finally got off my lazy butt to take a look under the car, and it's as you described. After covering the plug, did you tape it up onto the heat shield to keep it from swaying or just leave it as is--hanging loose? Also, are you experiencing any drone, or is it too annoying sound-wise if you ever opted to drive in comfort mode--but who does that?!?!

With my M3, I never found the need to permanently disable the flap, b/c of the sport/sport+ button which makes it easy to open/close.

[DBU]

I am not familiar with the G03 (X3 M40i), but I can tell you how it works on the F26 (X4 M40i). Keep in mind we have different motors (B58 vs N55), but I wouldn't be surprised if BMW left this unchanged on the G03.

To check this, take a look at under the car, behind the driver's side rear wheel. You will see the exhaust pipe has a valve that close and open the exhaust flap. You should be able to press firmly on the lever and by doing so open the valve. It is spring loaded and takes a firm press to move.

If you want it to stay open (for better sound), go to the trunk of the car. On the driver's side, you probably have a hard cover that is easily removed to gain access to some electrical modules (radio?)

Now look towards the very rear of the car and you should see a small solenoid attached to the chassis with a rubber mount. It will have two vacuum lines and an electrical connection. To leave the exhaust flap open whenever the motor is running, disconnecty both vacuum hoses from the solonoid and connect the two hoses with a male/male vacuum connector, bypassing the solonoid altogether. I found that a common garden sprinkler connector also works.

Whenever the motor starts, vacuum is sent straight to the valve and it will open - and stay open.

On the X4, engaging sport modes does not automatically open the valve. It seems the valve opens when the solonoid receives a signal from the computer at some point when the motor is asked to produce max, or near max, power.

[Kief]

Originally Posted by DBU

I am not familiar with the G03 (X3 M40i), but I can tell you how it works on the F26 (X4 M40i). Keep in mind we have different motors (B58 vs N55), but I wouldn't be surprised if BMW left this unchanged on the G03.

To check this, take a look at under the car, behind the driver's side rear wheel. You will see the exhaust pipe has a valve that close and open the exhaust flap. You should be able to press firmly on the lever and by doing so open the valve. It is spring loaded and takes a firm press to move.

If you want it to stay open (for better sound), go to the trunk of the car. On the driver's side, you probably have a hard cover that is easily removed to gain access to some electrical modules (radio?)

Now look towards the very rear of the car and you should see a small solenoid attached to the chassis with a rubber mount. It will have two vacuum lines and an electrical connection. To leave the exhaust flap open whenever the motor is running, disconnecty both vacuum hoses from the solonoid and connect the two hoses with a male/male vacuum connector, bypassing the solonoid altogether. I found that a common garden sprinkler connector also works.

Whenever the motor starts, vacuum is sent straight to the valve and it will open - and stay open.

On the X4, engaging sport modes does not automatically open the valve. It seems the valve opens when the solonoid receives a signal from the computer at some point when the motor is asked to produce max, or near max, power.

Appreciate you sharing the process, but can't you just unplug the connector I pictured above and all done?

[ed4]

Originally Posted by Kief

Appreciate you sharing the process, but can't you just unplug the connector I pictured above and all done?

I believe the solenoid is normally (or rest-state) closed, so by unplugging the module, this may permanently close the valve(s).

On my F10, I have this, which I use my Homelink to control:

http://exhaustmeister.com/

I haven't messed or looked into my G01 yet, so I don't know if this will work. In fact, I have not driven my G01 yet

[Kief]

Originally Posted by ed4

I believe the solenoid is normally (or rest-state) closed, so by unplugging the module, this may permanently close the valve(s).

Right...so as cthomp88 noted below, first get the valves open, and then unplug to permanently keep open. My only concern is any possible drone...

Originally Posted by cthomp88

I put mine in sport, to open the flap, and then there’s a plug on the left side exhaust. I unplugged that and taped/covered it up. That has kept the flap open permanently. My BF did the same thing on his M3.

[No1Cares]

I was under the assumption the exhaust flap valve on that side would open up if the sport mode button is selected...?

[DBU]

Originally Posted by Casotakar

I was under the assumption the exhaust flap valve on that side would open up if the sport mode button is selected...?

Speaking for the F26, that is NOT the case.

[DBU]

Originally Posted by Kief

Right...so as cthomp88 noted below, first get the valves open, and then unplug to permanently keep open. My only concern is any possible drone...

Not sure you are talking about unplugging the vacuum or the electrical connection. But either way, the spring will force it closed again.

Keep in mind that it appears these flaps apparently operate differently on M-cars and also on older Bimmers.

[No1Cares]

Originally Posted by Kief

Thanks.
I finally got off my lazy butt to take a look under the car, and it's as you described. After covering the plug, did you tape it up onto the heat shield to keep it from swaying or just leave it as is--hanging loose? Also, are you experiencing any drone, or is it too annoying sound-wise if you ever opted to drive in comfort mode--but who does that?!?!

With my M3, I never found the need to permanently disable the flap, b/c of the sport/sport+ button which makes it easy to open/close.

Originally Posted by DBU

Speaking for the F26, that is NOT the case.

I'm only referring to the 2018 m40i. is this the case?

[DBU]

Originally Posted by Casotakar

I'm only referring to the 2018 m40i. is this the case?

Looks like you will be the first one to tell the rest of the community how this actually works on the G01. Get on your knees, snap a photo, tell us how it works, man.

[Kief]

Originally Posted by DBU

Looks like you will be the first one to tell the rest of the community how this actually works on the G01. Get on your knees, snap a photo, tell us how it works, man.

Apparently @cthomp88 has already confirmed below:

Originally Posted by cthomp88

I put mine in sport, to open the flap, and then thereÂ’s a plug on the left side exhaust. I unplugged that and taped/covered it up. That has kept the flap open permanently. My BF did the same thing on his M3.

[No1Cares]

Originally Posted by DBU

Looks like you will be the first one to tell the rest of the community how this actually works on the G01. Get on your knees, snap a photo, tell us how it works, man.

got a nice laugh from that one. you're hilarious!

Originally Posted by Kief

Apparently @cthomp88 has already confirmed below:

right. I already saw that. I guess I'm just missing the point when there is already a button made for opening that valve. nvm then!

[Kief]

Originally Posted by Casotakar

I guess I'm just missing the point when there is already a button made for opening that valve. nvm then!

However, as others have noted, putting the car into Sport doesn't necessarily open up both valves continually

[KAP8]

Originally Posted by Kief

However, as others have noted, putting the car into Sport doesn't necessarily open up both valves continually

I'm confused. My wife and I only drive the car in Sport mode. So the left flap is closed upon start up, but is open continuously once warmed up?

[Kief]

Originally Posted by KAP8

I'm confused. My wife and I only drive the car in Sport mode. So the left flap is closed upon start up, but is open continuously once warmed up?

Despite him referencing his X4 M40i, I'm thinking DBU is correct about this:

Originally Posted by DBU

On the X4, engaging sport modes does not automatically open the valve. It seems the valve opens when the solonoid receives a signal from the computer at some point when the motor is asked to produce max, or near max, power.