BMW Mini exhaust flap - what is it?

[DJT]

Stop-start last night around M25 I was following a Mini Works Clubman. The silcener had two exits. The one on the right had a butterfly valve that was opening and closing. What is this? Some kind of emissions control? Thanks.

[Exige77]

Noisy pipe and a quiet pipe.

Ecu decides when to open flap on noisy pipe.

Some systems can be operated manually also.

[Trustmeimadoctor]

its only controlled by a bluetooth remote on the genuine pro exhaust not like the vacuum one on most bmw's

Yes it makes it noisy as pipe is straight from cat no back box on that side

[Fuzzarr]

I saw a similar thing happening on a new Fiesta ST the other day.

[DJT]

Ah, thanks. Thought that kind of thing was only done to muscle cars after market and would not be noise compliant. The Mini one was opening sometimes when moving quite slowly so perhaps the speed the throttle was jabbed tricked the ECU into thinking it was going to be soon needing large throttle input.

Edited by DJT on Thursday 4th April 17:44