i really think i have two totally separated pipes (one per bank). this is what i have under my car
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and when i was below the car, and here on the pictures i see no flapper. but i did see on some earlier bmw there was a flap you are talking about. where should flapper be located if i had one so i can go and check?

well i did remove my throttle body but it was hard to see whats on the bottom because of variable intake runners... but i did see it was not clear metal.. i did put some stick inside to see if it will get dirty. there was a layer of oil in there... so not a puddle but it was oily... could that be the reason for smoke even i have removed eventual source of oil supply to intake? or there is another way for oil to get in there? and i do not know exact construction of this intake and variable runners, is it possible that oil is pulled only into one head?