A common thread I know but having had an intermittant increased emissions warning I asked the BMW assistance technician to hook up his diagnostics equipment. He found that the mass air flow meter was leading to the (calculated?) air mix being to great. Mass air flow meter now replaced and car running a lot more smoother and seems to have gained more grunt.

BUT now I have an engine whine at 1700 to 2500 rpm. Is it the turbo gone funny or has the dealer done something else stupid

 

Maybe they installed new turbo system on your car that will debut soon on 335i

 

There is still just the one turbo on it not the 2 yet.