Exhaust Sound

TunafishE93 · 04-29-2021, 12:19 AM

I installed catless DP and car was much louder, mainly on starting (easily) from a stop. From what i understand the normal mode for exhaust is to keep one muffler open while starting out.

This led me to put it in sport exhaust in mhd. This seemed to quite down the exhaust from stop (again just cruising).

I read alot about sport mode makes cars louder. So what exactly have i enabled and why is not as louder (compared to mhd sport exhaust disabled)?

My thought is one muffler cant muffle as well as two??

CoffeeBean · 04-29-2021, 11:12 AM

That MHD option does nothing on your car. It's for newer models with the comfort/sport switch. I had a catless DP on my 335 and yeah it was loud on cold startup whether the flap was physically disabled or not. You can try disabling cold startup in MHD, but it might have problems idling.

TunafishE93 · 05-04-2021, 09:28 PM

Thanks for the info.

anjuna · 05-12-2021, 10:33 AM

Exhaust flap opens on start up, but is then also controlled by the load and RPM of engine during operation.

Additionally, the exhaust flap has a codewort for how it is controlled.

Find my settings below.
1. Exhaust flap is always open in Neutral/park and reverse.
2. Exhaust flap is always closed otherwise (I am currently trying it out as a methanol trigger, not actually exhaust).
3. The exhaust flap is open for 30 seconds on start.
4. Codewort is set to be "active" and controlled by load / RPM

Please note that some DME use opposing logic for open/closed. For me, 0 is open, 255 (scaled to 100) is closed.

Others have said that 255 (scaled to 100) is OPEN and 0 is CLOSED.

04-29-2021, 12:19 AM	#1
TunafishE93 Major 418 Rep 1,152 Posts Drives: BMW 335i Join Date: Dec 2019 Location: NV iTrader: (0)	Exhaust Sound I installed catless DP and car was much louder, mainly on starting (easily) from a stop. From what i understand the normal mode for exhaust is to keep one muffler open while starting out. This led me to put it in sport exhaust in mhd. This seemed to quite down the exhaust from stop (again just cruising). I read alot about sport mode makes cars louder. So what exactly have i enabled and why is not as louder (compared to mhd sport exhaust disabled)? My thought is one muffler cant muffle as well as two??
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04-29-2021, 11:12 AM	#2
CoffeeBean Lieutenant 226 Rep 553 Posts Drives: 640i M-Sport GC Join Date: Aug 2012 Location: AL iTrader: (2)	That MHD option does nothing on your car. It's for newer models with the comfort/sport switch. I had a catless DP on my 335 and yeah it was loud on cold startup whether the flap was physically disabled or not. You can try disabling cold startup in MHD, but it might have problems idling.
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05-04-2021, 09:28 PM	#3
TunafishE93 Major 418 Rep 1,152 Posts Drives: BMW 335i Join Date: Dec 2019 Location: NV iTrader: (0)	Thanks for the info.
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05-12-2021, 10:33 AM	#4
anjuna First Lieutenant 307 Rep 394 Posts Drives: f25 Join Date: Feb 2017 Location: houston iTrader: (0)	Exhaust flap opens on start up, but is then also controlled by the load and RPM of engine during operation. Additionally, the exhaust flap has a codewort for how it is controlled. Find my settings below. 1. Exhaust flap is always open in Neutral/park and reverse. 2. Exhaust flap is always closed otherwise (I am currently trying it out as a methanol trigger, not actually exhaust). 3. The exhaust flap is open for 30 seconds on start. 4. Codewort is set to be "active" and controlled by load / RPM Please note that some DME use opposing logic for open/closed. For me, 0 is open, 255 (scaled to 100) is closed. Others have said that 255 (scaled to 100) is OPEN and 0 is CLOSED.
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