BMW M3 Forum (E90 E92)

BMW Garage BMW Meets Register Search Today's Posts Mark Forums Read


Go Back   M3Post - BMW M3 Forum > E90/E92 M3 Technical Topics > Engine, Transmission, Exhaust, Drivetrain, ECU Software Modifications
 
Lux Angel Eyes
Post Reply
 
Thread Tools Search this Thread
      12-28-2008, 05:39 PM   #1
JuniorM3
Captain
 
JuniorM3's Avatar
 
Drives: BMW E92 M3 DTC Alpine White
Join Date: Dec 2008
Location: Ethiopia

Posts: 160
iTrader: (0)

Cool exhaust sound when just started

Can anyone tell me why the exhaust sound of our cars is cooler when we've just started it? (Cold start)

After 20 or some sec. it's gone.

There are no valves right?...

It's quite a big differance.
JuniorM3 is offline   Ethiopia
0
Reply With Quote
      12-28-2008, 06:11 PM   #2
pino9
Registered
 
Drives: 2009 BMW E93 M3 Convertible
Join Date: Dec 2008
Location: Brisbane QLD Australia

Posts: 3
iTrader: (0)

Exhaust sound

Because it's cold.
Once the engine and exhaust warms up, the sound changes.
pino9 is offline   Australia
0
Reply With Quote
      12-28-2008, 06:16 PM   #3
JuniorM3
Captain
 
JuniorM3's Avatar
 
Drives: BMW E92 M3 DTC Alpine White
Join Date: Dec 2008
Location: Ethiopia

Posts: 160
iTrader: (0)

Quote:
Originally Posted by pino9 View Post
Because it's cold.
Once the engine and exhaust warms up, the sound changes.
Mmmm strange. Because the sound change is sudden.
JuniorM3 is offline   Ethiopia
0
Reply With Quote
      12-28-2008, 07:34 PM   #4
VictorH
Lieutenant
 
Drives: '09 M3
Join Date: Dec 2007
Location: SC

Posts: 598
iTrader: (1)

I've noticed that too, but to me when it's cold it just sounds like a cammed up V-8 with a nice lope. When it's warm that lope is gone.
VictorH is offline  
0
Reply With Quote
      12-29-2008, 04:58 AM   #5
swamp2
Lieutenant General
 
swamp2's Avatar
 
Drives: E92 M3
Join Date: Sep 2006
Location: San Diego, CA USA

Posts: 10,135
iTrader: (1)

I've been told that it runs very rich for a short time when cold to get the cats up to temperature in order to decrease emissions quickly.
swamp2 is offline   United_States
0
Reply With Quote
      12-29-2008, 05:01 AM   #6
William Blake
Private First Class
 
Drives: 08 MINI Cooper S Clubman
Join Date: Nov 2008
Location: Europe

Posts: 105
iTrader: (0)

Initial warm-up of the engine.. after about 10-20 seconds it drops to normal idle.
William Blake is offline   Belgium
0
Reply With Quote
      01-01-2009, 03:54 PM   #7
biscuits
Dimmer than a dim thing
 
Drives: C63 AMG Coupe
Join Date: Oct 2008
Location: UK

Posts: 1,278
iTrader: (0)

Garage List
I foud out this noise is due to a "cold air pump" that runs for 10-20 seconds along with a load of fuel to warm the cats up.

Shame it doesn't sound like it all the time
biscuits is offline   United Kingdom
0
Reply With Quote
      01-01-2009, 06:55 PM   #8
Oakleyguy
Resident Engineer
 
Oakleyguy's Avatar
 
Drives: M4 (VPC) & Land Cruiser
Join Date: Oct 2008
Location: Denver, CO / Tulsa, OK

Posts: 476
iTrader: (0)

Garage List
2015 BMW M4  [5.00]
2005 Toyota UZJ100  [0.00]
+1
Oakleyguy is offline   United_States
0
Reply With Quote
      01-01-2009, 07:20 PM   #9
BimmerRob08
Major
 
BimmerRob08's Avatar
 
Drives: 2008 M3, Space Gray
Join Date: Mar 2008
Location: KIKR (ABQ), NM

Posts: 1,257
iTrader: (0)

In the manual it says that on cold start up the engine may sound "metalic" Not sure if I'd call it metalic but does sound different at start up. The cold-pump and burning rich for cat heating does make good sence on why it'll sound like that. I actually like the sound after it has warmed up a bit as it prrrs a bit better IMO.
BimmerRob08 is offline   United_States
0
Reply With Quote
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
Forum Jump


All times are GMT -5. The time now is 04:57 PM.




m3post
Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
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