ben53

I live in WA and its pretty cold out here.
I noticed that the smoke comes out of the exhaust pipes when I start the car in cold am until it warms up! pretty normal.
But what worries me is that the smoke was coming only from one exhaust pipe and not from the other. It is happening everyday!
Is it normal? If not, what could be the probable reason ?

Thanks!

SilberGrauE60

Yes, it could be perfectly normal. At least on the 545i, the exhaust is bi-modal, meaning it comes out of the left pipe only until the RPM rises above 3,500 or so, then a valve opens and it comes out both tips. If you look under your exhaust tips, you should be able to see an actuator on the right hand tip. If so, then you have the bi-modal exhaust. In fact, if you pay attention in the lower gears (1 or 2) you will notice an increase in power and sound passing through this RPM range.

robself705

Yes, there are exhaust flaps in most of the BMWs to reduce loud startup noise. They open when needed under load.