THE LARGEST BMW 2-SERIES FORUM ON THE PLANET
2Addicts
2Addicts
BMW Garage BMW Meets Register Search Today's Posts Mark Forums Read
2Addicts | BMW 2-Series forum Technical Topics N55 (M235i) Engine, Transmission, Exhaust, Tuning Exhaust flap mod/Active Sound Question

Post Reply
 
Thread Tools Search this Thread
      01-03-2015, 03:02 PM   #1
kd0t
Banned
116
Rep
628
Posts

Drives: M235i
Join Date: Oct 2014
Location: SoCal

iTrader: (0)

Exhaust flap mod/Active Sound Question

Hi everyone! Hope you all had a wonderful holiday.

So I did the exhaust flap mod and I love it.. My question is: I realized that even after the "mod" the car is still louder in Sport/Sport+ modes. Is this the result of the faux engine noise piping through the speakers?
Appreciate 0
      01-03-2015, 04:36 PM   #2
bman6074
Major
69
Rep
1,254
Posts

Drives: 14 M235i and 07 Lotus Exige S
Join Date: Feb 2008
Location: Connecticut

iTrader: (0)

Is this the gold T mode like on the 135i?
__________________
Appreciate 0
      01-03-2015, 04:58 PM   #3
pikcachu
Brigadier General
pikcachu's Avatar
911
Rep
4,709
Posts

Drives: M235i (F22 Red angel)
Join Date: Jul 2011
Location: undisclosed

iTrader: (0)

Quote:
Originally Posted by bman6074
Is this the gold T mode like on the 135i?
No, the 2 it's electric so there is nothing to plug

I think you just disconnect the connector while the flap is open
Appreciate 0
      01-03-2015, 04:59 PM   #4
pikcachu
Brigadier General
pikcachu's Avatar
911
Rep
4,709
Posts

Drives: M235i (F22 Red angel)
Join Date: Jul 2011
Location: undisclosed

iTrader: (0)

Quote:
Originally Posted by kd0t
Hi everyone! Hope you all had a wonderful holiday.

So I did the exhaust flap mod and I love it.. My question is: I realized that even after the "mod" the car is still louder in Sport/Sport+ modes. Is this the result of the faux engine noise piping through the speakers?
Yes it's probably the asd through the speakers
Appreciate 0
      01-04-2015, 01:46 AM   #5
kd0t
Banned
116
Rep
628
Posts

Drives: M235i
Join Date: Oct 2014
Location: SoCal

iTrader: (0)

Hmm.. Not sure if I want to remove it then. Sounds pretty mean haha
Appreciate 0
      01-04-2015, 09:08 AM   #6
m2ruder
Brigadier General
m2ruder's Avatar
United_States
1103
Rep
3,150
Posts

Drives: '15 Alfa Romeo 4c coupe
Join Date: Aug 2012
Location: Charlotte

iTrader: (6)

So instead of starting a new thread for this question I will tack onto the OP because it is similar.

I installed the MPE and when at start up the flap is closed the exhaust is very loud. At 5am in the morning in the garage on a work day it really resonates. I was thinking about doing the mod so it is open all the time and it would be quieter at start up but not sure what the negative effects would be and why it exactly exists in the first place. Is it to help CAT warm up and/or the get the EGT's up quicker? I would have thought when you upgrade to a M performance exhaust this would be one of the items they would do away with so I figured there was a legitimate reason.

Sorry for all the wind.....thanks

Last edited by m2ruder; 01-04-2015 at 11:42 AM..
Appreciate 0
      01-04-2015, 01:40 PM   #7
kd0t
Banned
116
Rep
628
Posts

Drives: M235i
Join Date: Oct 2014
Location: SoCal

iTrader: (0)

Quote:
Originally Posted by ehagerty
So instead of starting a new thread for this question I will tack onto the OP because it is similar.

I installed the MPE and when at start up the flap is closed the exhaust is very loud. At 5am in the morning in the garage on a work day it really resonates. I was thinking about doing the mod so it is open all the time and it would be quieter at start up but not sure what the negative effects would be and why it exactly exists in the first place. Is it to help CAT warm up and/or the get the EGT's up quicker? I would have thought when you upgrade to a M performance exhaust this would be one of the items they would do away with so I figured there was a legitimate reason.

Sorry for all the wind.....thanks
I've heard it's only open on one exhaust during cold start to help warm up faster.

I'm not sure if doing the exhaust flap mod would make it quieter though.. I could be wrong but my brother said it's actually louder inside the house when I cold start my car.

What you can try to do is maybe back up to the driveway after you start it? And let it warm up there - so the sound doesn't get amplified in the garage
Appreciate 0
      01-04-2015, 03:50 PM   #8
m2ruder
Brigadier General
m2ruder's Avatar
United_States
1103
Rep
3,150
Posts

Drives: '15 Alfa Romeo 4c coupe
Join Date: Aug 2012
Location: Charlotte

iTrader: (6)

Yes you are correct...I just did the unplug and stow away mod. Right away I didn't see much in lower volume at start up. I made sure the car was full cold...have not driven since yesterday and the flap was open when I unplugged it. Most of the noise and exhaust gasses come out of the pipe nearest to the inlet side and when it is hot, it still is mainly coming out of that side....I even verified the flap is full open. So I guess at idle and possibly lower rpm's the exhaust is not really that balanced like a true single center entry dual exit. It mainly relies on the passenger side entry/exit and that is why that exit pipe gets discolored and the other side stays clean...for the most part.

I will run it for a bit like this and see what the out come is...the MPE only has about 200mi on it so it still needs to open up
Appreciate 0
      01-04-2015, 11:58 PM   #9
eboosted
Private First Class
Peru
19
Rep
144
Posts

Drives: x6 5.0i xdrive 2009
Join Date: Mar 2011
Location: the world

iTrader: (0)

Would you be able to post a pic of the MPE and location of the flap electrical connector?
Appreciate 0
      01-05-2015, 05:12 AM   #10
m2ruder
Brigadier General
m2ruder's Avatar
United_States
1103
Rep
3,150
Posts

Drives: '15 Alfa Romeo 4c coupe
Join Date: Aug 2012
Location: Charlotte

iTrader: (6)

Same place as the stock unit...mounted on top of the left side exit pipe
Attached Images
 
Appreciate 0
      01-05-2015, 08:19 AM   #11
alz0rz
What goes here?
alz0rz's Avatar
307
Rep
1,243
Posts

Drives: 2016 F80 M3
Join Date: Aug 2011
Location: Indy

iTrader: (4)

Garage List
2016 BMW M3  [0.00]
2014 BMW M235i  [0.00]
I too hate how loud the car is at start-up. It stays like this for about 30 seconds. An easy way around this is just to apply very light throttle for the first 30 seconds and that will lower the volume dramatically.
__________________
'16 F80 M3
Appreciate 0
      01-05-2015, 09:06 AM   #12
BD_F22
BD_e92
United_States
311
Rep
1,756
Posts

Drives: 2015 m235i xDrive
Join Date: Nov 2012
Location: NYC

iTrader: (9)

Keeping the flap opened will make it louder on cold start.. Just look up golf tee mod on the e9x platform. If it's too loud now don't ever get a downpipe because it will make it even louder.. On my e92 I had catless downpipes with a full catback exhaust and on cold start it was loud enough to resonate through the whole house and in public garages was loud enough to set off alarms haha
Appreciate 0
      01-07-2015, 02:07 AM   #13
Cal
Second Lieutenant
17
Rep
203
Posts

Drives: M3, 535i.
Join Date: Feb 2006
Location: CA

iTrader: (0)

The flap supposedly also opens/closes depending on the RPM to eliminate low RPM drone. With the flap always open, some have reported some drone at highway cruising in low rpms.

OP, do you notice any droning in the low rpm range (say around 2-3k rpm)?
Appreciate 0
      01-08-2015, 04:11 PM   #14
M2-BM35i
Private First Class
40
Rep
148
Posts

Drives: M235i
Join Date: Mar 2012
Location: UK

iTrader: (0)

MPE and location of the flap electrical connector?

Pardon my ignorance but I can't find the first thread...
how do I go about opening the flap permanently - I do see the pic above but not sure exactly what to do with the MPE / flap electrical connector in order to open the flap?

Thanks
Appreciate 0
      01-08-2015, 05:30 PM   #15
kd0t
Banned
116
Rep
628
Posts

Drives: M235i
Join Date: Oct 2014
Location: SoCal

iTrader: (0)

Quote:
Originally Posted by Cal
The flap supposedly also opens/closes depending on the RPM to eliminate low RPM drone. With the flap always open, some have reported some drone at highway cruising in low rpms.

OP, do you notice any droning in the low rpm range (say around 2-3k rpm)?
Hey Cal! Long time.

I wouldn't call it drone.. It's barely more noticeable but just enough to remind you that you unplugged it haha
Appreciate 0
      01-08-2015, 05:32 PM   #16
kd0t
Banned
116
Rep
628
Posts

Drives: M235i
Join Date: Oct 2014
Location: SoCal

iTrader: (0)

Quote:
Originally Posted by 1-BMW-35i
Pardon my ignorance but I can't find the first thread...
how do I go about opening the flap permanently - I do see the pic above but not sure exactly what to do with the MPE / flap electrical connector in order to open the flap?

Thanks
Drive around in sport mode for a few mins.

Turn the car off while in sport.

Check inside the driver side exhaust tip if it's open.

If it is, unplug the connection and tape up the head to the side.
Appreciate 0
      01-08-2015, 11:52 PM   #17
M2-BM35i
Private First Class
40
Rep
148
Posts

Drives: M235i
Join Date: Mar 2012
Location: UK

iTrader: (0)

Quote:
Originally Posted by kd0t View Post
Drive around in sport mode for a few mins.

Turn the car off while in sport.

Check inside the driver side exhaust tip if it's open.

If it is, unplug the connection and tape up the head to the side.

Great, thanks, I'll do this and see how she sounds (I have M Sport exhaust on as well)

Does it throw code errors on ECU?
Appreciate 0
      01-09-2015, 12:22 AM   #18
kd0t
Banned
116
Rep
628
Posts

Drives: M235i
Join Date: Oct 2014
Location: SoCal

iTrader: (0)

Quote:
Originally Posted by 1-BMW-35i
Quote:
Originally Posted by kd0t View Post
Drive around in sport mode for a few mins.

Turn the car off while in sport.

Check inside the driver side exhaust tip if it's open.

If it is, unplug the connection and tape up the head to the side.

Great, thanks, I'll do this and see how she sounds (I have M Sport exhaust on as well)

Does it throw code errors on ECU?
It's going to sound like you're in sport mode when you're not.

No errors that light up on the dash.

But I realized that even with this mod, sport mode still seems louder which is probably the fake engine noise piping through the speakers.
Appreciate 0
      01-09-2015, 12:37 AM   #19
M2-BM35i
Private First Class
40
Rep
148
Posts

Drives: M235i
Join Date: Mar 2012
Location: UK

iTrader: (0)

Quote:
Originally Posted by kd0t View Post
It's going to sound like you're in sport mode when you're not.

No errors that light up on the dash.

But I realized that even with this mod, sport mode still seems louder which is probably the fake engine noise piping through the speakers.

Great... I like loud... music to my ears...

Worried about error code though... motorplan issue... is it worth the risk?
Appreciate 0
      01-09-2015, 05:35 AM   #20
m2ruder
Brigadier General
m2ruder's Avatar
United_States
1103
Rep
3,150
Posts

Drives: '15 Alfa Romeo 4c coupe
Join Date: Aug 2012
Location: Charlotte

iTrader: (6)

All,
1st. he flap should be open before 1st start up so before you drive the car just go down and unplug the motor...no errors show.

2nd. I am switching mine back. It could be my imagination but it seems when I start to get on the gas below 2k the car resonates & vibrates a lil more Does anyone really know if the flap is an active tpe design or just off at start up and pen the rest of the time. I mean does it vary its position depending on RPM like possibly close up at lower rpms? Prolly just the way the MPE resonates but I will plug it back in this weekend and drive for a week to see if it is still there. I have not seen any advantage sound wise having it unplugged so I might go the route of the BMW engineers
Appreciate 0
      05-15-2019, 08:57 PM   #21
zeyad.habeeb
Private
zeyad.habeeb's Avatar
9
Rep
53
Posts

Drives: 435
Join Date: Oct 2018
Location: san diego

iTrader: (0)

Quote:
Originally Posted by m2ruder View Post
Same place as the stock unit...mounted on top of the left side exit pipe
I have 435i and i changed the muffler to the M muffler. But it doesn't open when i put it to sport mode ? I don't see it open even in cold start,

I test drove 440i and i see the flap will open when you put it to sport mode.
Appreciate 0
Post Reply

Bookmarks

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -5. The time now is 05:46 AM.




2addicts
Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2019, vBulletin Solutions Inc.
1Addicts.com, BIMMERPOST.com, E90Post.com, F30Post.com, M3Post.com, ZPost.com, 5Post.com, 6Post.com, 7Post.com, XBimmers.com logo and trademark are properties of BIMMERPOST