my 540i is running rough,shifting rough,exhaust white smoke,and smells like fuel mixture is too rich
rough running bmw 540i on 1997 BMW 540i
PCV valve on back of intake manifold. common fault. diagnostic codes won't show for this fault and unless techi knows these cars he won't know what the problem is,
You really need to get it diagnosed by a BMW specialty shop to see what causing the problems. They should be able to pull out diagnostic trouble codes from the affected modules and be able to estimate the parts and repair cost for you.