[nt25940]

During the cold weather I noticed there was no vapor coming out of the passenger side tail pipe. On the driver's side the vapor was completely visible. I then placed my hand on the passenger side tail pipe and it was completely cold, where as the driver's side tail pipe was hot. Anybody here of this?

[ToddRGuy]

Originally Posted by nt25940

During the cold weather I noticed there was no vapor coming out of the passenger side tail pipe. On the driver's side the vapor was completely visible. I then placed my hand on the passenger side tail pipe and it was completely cold, where as the driver's side tail pipe was hot. Anybody here of this?

A keen observation! Yes, this is completely normal. The BMW exhaust system has valves that control this. On startup, especially in cold weather, one flap remains closed to assist in more rapid warming of the engine. I don’t know the exact timing, but at some point it will transition back to duel exhaust.

[tsbrown]

Originally Posted by ToddRGuy

A keen observation! Yes, this is completely normal. The BMW exhaust system has valves that control this. On startup, especially in cold weather, one flap remains closed to assist in more rapid warming of the engine. I don’t know the exact timing, but at some point it will transition back to duel exhaust.

That valve should open in Sport mode and stay closed in Comfort and Eco Pro mode, or whatever the equivalents are in the G60. If open when the engine is running (in Sport mode), it then closes when the engine is turned off.

[SkykingUSA]

Lately at night when I'm following some newer BMW vehicles, my headlights shine right into the exhaust tips and I can see a little butterfly valve open and close on the driver's side exhaust. It usually changes as they slow to a traffic light, then again when they move off from a stop after the light turns green. Interesting.

[ToddRGuy]

Originally Posted by tsbrown

That valve should open in Sport mode and stay closed in Comfort and Eco Pro mode, or whatever the equivalents are in the G60. If open when the engine is running (in Sport mode), it then closes when the engine is turned off.

Those are the same modes on the G60. I knew they closed in those two modes, during normal operation, but what I wasn’t sure of is how the selected mode impacted its decision during a cold start. It’s all onboard computer logic but it would be interesting to know.

[tsbrown]

Originally Posted by ToddRGuy

Those are the same modes on the G60. I knew they closed in those two modes, during normal operation, but what I wasn’t sure of is how the selected mode impacted its decision during a cold start. It’s all onboard computer logic but it would be interesting to know.

My statement above is based on my observations with my G30, including swapping the exhaust and trying to get more sound out of it. My cold start always has the valve closed, most noticeable in actual cold weather like we’re having now. The valve stays closed in comfort mode to align the quieter exhaust sound with comfort settings and opens in sport mode to allow the louder/sportier sound. I eventually went back to the stock exhaust and had to refit the spring that connects to solenoid to the flap and had to make sure it was opening/closing properly. Someone who’s investigated the actual coding may say it’s more nuanced but that’s what I’ve observed.