butterfly valve in exhaust

B

BLZ

Member
 Blackpool, Lancashire
Does anyone know what the butterfly valve does in the exhaust? It seems to be open but will close if you use your finger but it springs back to open. I have read about active exhaust valves. The question is should the valve be open or closed when the car engine is cold?
 
It should remain closed at all times and only opens up when revving (eg over 5000rpm) or under heavy acceleration

Designed for those that want a quieter exhaust notes when doing day to day driving and noise when out having a quick blast.

I suspect the spring has broken, hence why its always in the open position
 
It's for emissions control (noise).

Closed at cold start then opens. Closes as revs rise until specific revs and throttle position where it opens again.
 
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