Normal, the left kicks in at higher rpm. It's a frequent newby query.

Good luck.

 

Thank you, Gary.

If you do mind, can you tell me why BMW designed that way?
Other cars like Toyota, Nissan with two pipes, they discharge equal amount of smoke. I was looking so closely every time I see one of them on the road.


Thanks.

 

I noticed that the right exhaust pipe is darker than the one on the left.
There is more smoke coming out from right side than from left side.

I called my BMW dealer and was told that the right one is the main pipe and any extra smoke will come out from left side.
Is this normal.

Please advise.

Thanks.

Your BMW dealer sounds like an idiot but yes, it's normal. The left exhaust pipe has an ECU-controlled flap that closes below ~3500 RPM to quiet the exhaust. It's not for "extra smoke".

Do a search for "exhaust flap" and you'll find a wealth of information on this topic, including how to easily disable it if you so choose.

 

Hey I tried doing an 'exhaust flap' search and didn't find anything useful at all. Just a couple 7 series posts. I am interested in increasing my muffler note a bit if I could without swapping out the pair... how do I go about disabling the flap?

 

DIY with pics are here.

 

Here but there ^ first:

http://www.e90post.com/forums/showthread.php?t=80661

 

Thank you Berfs and Gary, I am doing this mod the next time I'm hoping in my car! Wow, this is great, I always wanted a deeper note like the one i get when i'm above 3500rpm or so. Do you guys have this 'mod' if you will, on your car? How do you like it?

 

I did this mod and I LOVE it:thumbup:

 

I’ve been running that way for almost a year. The note has a little extra growl, especially at idle and low rpm. It sounds more like the way it should have been designed in the first place.

I’ve reconnected it only a of couple times for all day 700 mile highway drives, for a more quiet and laid back highway cruise. That’s the beauty of this “mod”, completely reversible in under 2 minutes.

 

I've been running that way for almost a year. The note has a little extra growl, especially at idle and low rpm. It sounds more like the way it should have been designed in the first place.

I've reconnected it only a of couple times for all day 700 mile highway drives, for a more quiet and laid back highway cruise. That's the beauty of this "mod", completely reversible in under 2 minutes.

+1, like it sometimes, don't sometimes (like extended hwy trips, btw-12 miles is extended for me).

GL