Exhaust Flaps configurations

ATL0501 · 06-18-2017, 10:23 AM

I am just trying to figure out each mode that keeps the exhaust flaps open without the golf-T mod. I can't tell if Sport mode (chassis only) has both flaps open or if I'm just hearing the Active Sound inside the cabin.
Note: I have the DHP to alter the sport mode between chassis and drivetrain or both.

ECO: Both flaps always open
Comfort: 1 flap open
Sport (drivetrain/chassis): Both flaps always open
Sport (chassis only): ????
Sport +: Both flaps always open

ATL0501 · 07-19-2017, 05:17 AM

Bump

CalCarNut · 07-19-2017, 06:42 PM

from a sticky..

This question comes up all of the time, so I have asked a moderator, Dackelone, to sticky this so it can be at the top of the forum for everyone to see, although I'm sure this won't stop people from asking still.

It is completely normal for exhaust gas to come out of only one of your two exhaust tips, and for only one to look dirty most of the time.

This is because the exhaust on our cars is valved, meaning it has a "flap" inside one of the pipes, and can be controlled electronically by the car for various reasons. In most cases, the flap will be closed, and this is the default setting for both Eco Pro and Comfort mode, this is why you see one tip clean and one tip dirty. In Sport and Sport+, it is open.

Here is a summary of the function of the flap (to my best knowledge):
Flap closed on startup to help warm up the cat's faster.
Flap will open itself when the car reaches idle, and will typically open itself when the car is idling.
After driving away in either Comfort or Eco Pro, the flap will close, and remain closed unless you give the car hard throttle.
The flap will remain open in Sport and Sport+ mode.

ATL0501 · 07-19-2017, 06:49 PM

Thanks for the feedback.

Per my question above, in sport mode does flap open when only chassis is selected or both drivetrain AND chassis have to be selected?

ipilcher · 07-20-2017, 07:50 AM

Is the flap open or closed when the car is not running (or does it vary)?

I'm considering undoing the golf tee mod, so this would be useful to know.

kimoboy · 08-05-2017, 05:20 PM

Is there any power gain if the flap is open all the time.

06-18-2017, 10:23 AM	#1
ATL0501 Private First Class 16 Rep 190 Posts Drives: '21 540 Msport Join Date: Dec 2014 Location: NJ iTrader: (0)	Exhaust Flaps configurations I am just trying to figure out each mode that keeps the exhaust flaps open without the golf-T mod. I can't tell if Sport mode (chassis only) has both flaps open or if I'm just hearing the Active Sound inside the cabin. Note: I have the DHP to alter the sport mode between chassis and drivetrain or both. ECO: Both flaps always open Comfort: 1 flap open Sport (drivetrain/chassis): Both flaps always open Sport (chassis only): ???? Sport +: Both flaps always open __________________ Bernina Grey Amber Effect 21 540 Msport Carbon Black/Cognac 21 X3 x30i M sport Black Sapphire 14 328Xi M sport
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07-19-2017, 05:17 AM	#2
ATL0501 Private First Class 16 Rep 190 Posts Drives: '21 540 Msport Join Date: Dec 2014 Location: NJ iTrader: (0)	Bump __________________ Bernina Grey Amber Effect 21 540 Msport Carbon Black/Cognac 21 X3 x30i M sport Black Sapphire 14 328Xi M sport
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07-19-2017, 06:42 PM	#3
CalCarNut Brigadier General 1061 Rep 3,258 Posts Drives: 2015 F36 Jet Black Sport Line Join Date: Apr 2015 Location: Blue Skies iTrader: (0) Garage List 2012 BMW X3 [0.00] 2015 BMW 428i Gran ... [10.00] 1996 Chevrolet Impa ... [8.00]	from a sticky.. This question comes up all of the time, so I have asked a moderator, Dackelone, to sticky this so it can be at the top of the forum for everyone to see, although I'm sure this won't stop people from asking still. It is completely normal for exhaust gas to come out of only one of your two exhaust tips, and for only one to look dirty most of the time. This is because the exhaust on our cars is valved, meaning it has a "flap" inside one of the pipes, and can be controlled electronically by the car for various reasons. In most cases, the flap will be closed, and this is the default setting for both Eco Pro and Comfort mode, this is why you see one tip clean and one tip dirty. In Sport and Sport+, it is open. Here is a summary of the function of the flap (to my best knowledge): Flap closed on startup to help warm up the cat's faster. Flap will open itself when the car reaches idle, and will typically open itself when the car is idling. After driving away in either Comfort or Eco Pro, the flap will close, and remain closed unless you give the car hard throttle. The flap will remain open in Sport and Sport+ mode. __________________ 2015 BMW F36 428i JetBlack. Sport Line Edition 25% 3M Tint\|
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07-19-2017, 06:49 PM	#4
ATL0501 Private First Class 16 Rep 190 Posts Drives: '21 540 Msport Join Date: Dec 2014 Location: NJ iTrader: (0)	Thanks for the feedback. Per my question above, in sport mode does flap open when only chassis is selected or both drivetrain AND chassis have to be selected? __________________ Bernina Grey Amber Effect 21 540 Msport Carbon Black/Cognac 21 X3 x30i M sport Black Sapphire 14 328Xi M sport
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07-20-2017, 07:50 AM	#5
ipilcher Captain 450 Rep 951 Posts Drives: 2024 M3 Compensation Join Date: Nov 2013 Location: North Texas, USA iTrader: (0)	Is the flap open or closed when the car is not running (or does it vary)? I'm considering undoing the golf tee mod, so this would be useful to know.
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08-05-2017, 05:20 PM	#6
kimoboy Second Lieutenant 47 Rep 292 Posts Drives: E90 335i Join Date: Sep 2014 Location: Earth iTrader: (0)	Is there any power gain if the flap is open all the time.
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