[Hellraiserharris]

Does anybody know how to make the exhaust flap stay open all the time on the new 435i. It's probably the same as the 135&335. I tried unplugging it when it was cold first thing in the morning. I tried it when the car was hot after driving about 30 miles. When I feel the exhaust it's always closed. Wtf. Is mine not working. How do I make it or when is it suppose to open?

[Bernard335]

It supposed to open after 1 minute on Cold Starts, you can actually hear it opening

[SomeRandomer123]

Yeah you'll have it open within ~30-60 sec of cold start and it's quite audible when it operates. Spirited throttle application or just booting it will also open it.

Isn't there a "U" clip that can be pulled out and the flap fastened back if you want to keep it open?

[crono06]

Does setting the car in Sport mode open up the flap as well? I swear whenever I put it to Sport, the exhaust is more audible. Just as reference, I have Sport mode set to chassis only (regular/Comfort setting throttle/drivetrain).

[raleedy]

If keeping it open were a good idea, wouldn't it have been designed that way?

[DrivenByE30]

If you're going to keep it open all the time, you're gonna raise hell Harris !

They designed it that way, probably a good idea to keep leave it as is...

I am not sure why you want to mess wit it.

[Halsifer]

Originally Posted by crono06

Does setting the car in Sport mode open up the flap as well? I swear whenever I put it to Sport, the exhaust is more audible. Just as reference, I have Sport mode set to chassis only (regular/Comfort setting throttle/drivetrain).

When I asked BMW for specifics of when the exhaust will be open, they said during cold starts, the left exhaust pipe will be closed for approximately 1 - 2 minutes. I was told they designed this for both noise-control reasons and vehicle warm-up. You will then here it open up and it will remain open.

However, while driving in Comfort or Eco Pro, it will adapt to driving habits. If you are not accelerating harshly, it will keep it closed most of the time to give off less sound. If you floor it though, it will open up. It will continue to open in close based on how much you are trying to accelerate.

When in Sport/Sport+ mode, the exhaust flap will remain completely open and the exhaust will start having more noise (the gurgling sound) whenever the engine RPM is decreasing. To hear what I'm talking about, roll down your windows and manually downshift to kick up your engine RPM to around 2500 - 3000 RPM and let the engine speed decrease. I usually hear it gurgle most if the RPM decreases near that range that.

Sport will also make the shifting 'grunt' noise more often in Sport mode. When accelerating hard, with the throttle past half way, manually shift around 4500 RPM and you will hear the noise I'm talking about. They didn't specify this but I believe the shifting noise is only with the Sport Auto.

Hope this helps..

[DVC]

Originally Posted by DrivenByE30

They designed it that way, probably a good idea to keep leave it as is...

I am not sure why you want to mess wit it.

The theory is that it only closes to keep the exhaust noise down so that the car sounds more "civil" in most situations.
But I have also wondered if there were any other reasons why forcing the flap to remain open all the time might be counter-productive...

[Bahn360Photo]

search golf t mod, there is a good thread with pics that i used

[Hellraiserharris]

Originally Posted by DrivenByE30

If you're going to keep it open all the time, you're gonna raise hell Harris !

They designed it that way, probably a good idea to keep leave it as is...

I am not sure why you want to mess wit it.

I did it on my 09 335. It just sounds better than me. Also it doesn't look like a fake dual exhaust when it humid or cold outside. My 13 535 didn't have the flap. Guess it's just the smaller cars.

[Hellraiserharris]

I was told to unplug it while it was open. I will try in sport mode to see if that works.

[RoundelM3]

Originally Posted by Hellraiserharris

I did it on my 09 335. It just sounds better than me. Also it doesn't look like a fake dual exhaust when it humid or cold outside. My 13 535 didn't have the flap. Guess it's just the smaller cars.

Completely different exhaust setup on the older models...the flap was vacuum operated, and there were two distinct exhaust pipes all the way from the turbo to the tips. N55 has one large pipe and one muffler with a pipe exiting from each side and making a 90 degree bend to point straight back; the flap is electronically operated on the stock and MPE mufflers.

As a previous poster stated, the purpose is essentially "noise control" and only restricts the exhaust on cold starts or when cruising in Eco Pro or Comfort modes. I considered unplugging it on my MPE, but decided to just leave it as is, as it sounds fine once it's warmed up. Probably wouldn't hurt to unplug, though.

[reprod]

I also have a 435 and I had the same issue as OP. The exhaust is just too muted in Comfort. Even in Sport mode if you only have DHP programmed for "Chassis Only" the 2nd exhaust will essentially never open unless driven aggressively (not a regular thing for city drivers). In addition, with the 435, the 2nd exhaust does not open after a set time.

OP, I followed these steps to get my 2nd exhaust to stay open permanently.

• Set DHP settings back to Chassis and Drivetrain for Sport mode
• Place the car in Sport Mode
• Rev the engine in Park to about 4000-5000 RPM
• Verify the left exhaust to be open
• With the car on and left exhaust open, unclip the actuator on the left exhuast pipe
• Secure the wire/clip and cover the actuator port to avoid and water/salt damage

I do not have any pictures right now, but get under there and take a look. Let us know if you still have any questions.

[BEAR-AvHistory]

You can't unplug it in the trunk like the E92?

[reprod]

Originally Posted by BEAR-AvHistory

You can't unplug it in the trunk like the E92?

No, you actually have to get under the car now.

[Coolhydro]

I been driving with the flap open since 4 months. It sounds a lot better than stock.
I just unplugged the wire/plug and used some adhesive tape. Its under the left exhaust.

[DVC]

Originally Posted by roundel335

Completely different exhaust setup on the older models...the flap was vacuum operated, and there were two distinct exhaust pipes all the way from the turbo to the tips. N55 has one large pipe and one muffler with a pipe exiting from each side and making a 90 degree bend to point straight back; the flap is electronically operated on the stock and MPE mufflers.

As a previous poster stated, the purpose is essentially "noise control" and only restricts the exhaust on cold starts or when cruising in Eco Pro or Comfort modes. I considered unplugging it on my MPE, but decided to just leave it as is, as it sounds fine once it's warmed up. Probably wouldn't hurt to unplug, though.

Is the flap always open anyway in Sport drivetrain settings (after cold start-up)? If so, I may just skip it...

Originally Posted by Coolhydro

I been driving with the flap open since 4 months. It sounds a lot better than stock.
I just unplugged the wire/plug and used some adhesive tape. Its under the left exhaust.

Are you driving around in Comfort mode? Or do you feel like it is also making a difference in Sport mode? (If so, is it only in certain situations, like at low RPMs?)

[Coolhydro]

It makes more noise in all modes. In sport you can hear it burble a bit louder.

[Hellraiserharris]

Originally Posted by reprod

I also have a 435 and I had the same issue as OP. The exhaust is just too muted in Comfort. Even in Sport mode if you only have DHP programmed for "Chassis Only" the 2nd exhaust will essentially never open unless driven aggressively (not a regular thing for city drivers). In addition, with the 435, the 2nd exhaust does not open after a set time.

OP, I followed these steps to get my 2nd exhaust to stay open permanently.

• Set DHP settings back to Chassis and Drivetrain for Sport mode
• Place the car in Sport Mode
• Rev the engine in Park to about 4000-5000 RPM
• Verify the left exhaust to be open
• With the car on and left exhaust open, unclip the actuator on the left exhuast pipe
• Secure the wire/clip and cover the actuator port to avoid and water/salt damage

I do not have any pictures right now, but get under there and take a look. Let us know if you still have any questions.

I will give this a shot this afternoon. When I get off of work. Thanks

[reprod]

Originally Posted by Hellraiserharris

I will give this a shot this afternoon. When I get off of work. Thanks

Great, let us know if it all works out.

[Hellraiserharris]

Originally Posted by reprod

I also have a 435 and I had the same issue as OP. The exhaust is just too muted in Comfort. Even in Sport mode if you only have DHP programmed for "Chassis Only" the 2nd exhaust will essentially never open unless driven aggressively (not a regular thing for city drivers). In addition, with the 435, the 2nd exhaust does not open after a set time.

OP, I followed these steps to get my 2nd exhaust to stay open permanently.

• Set DHP settings back to Chassis and Drivetrain for Sport mode
• Place the car in Sport Mode
• Rev the engine in Park to about 4000-5000 RPM
• Verify the left exhaust to be open
• With the car on and left exhaust open, unclip the actuator on the left exhuast pipe
• Secure the wire/clip and cover the actuator port to avoid and water/salt damage

I do not have any pictures right now, but get under there and take a look. Let us know if you still have any questions.

This worked. Thanks.

[mcli]

I have the borla s-type catback installed, and it doesn't have the flap at all. No issues, just louder during normal use. The guys at the dealership love that about the vehicle when I bring it in for service.

Interesting note on the borla exhaust: it has a mount point for the exhaust flap control even though it's inactive. Kinda nice of them to include.