I am sure many of you have seen this thread on bimmerfest:

Looks like i Finally discovered BMW V8 secret!!! - Bimmerfest - BMW Forums

I am having my valve covers done and I am trying to decide whether to try replacing the CPS's on my 06 550i. As far as I can tell these sensors are actually on the valve covers so it won't cost me that much to do it. I don't have any codes but my car definitely has the symptoms described in the thread.

Has anybody with 550i or 545i try doing this?

I have started doing engine flush with the liqui-moly product prior to draining the oil and seems to make a noticeable some difference and I am starting to think there might be some truth to it.

On a different note, my car has almost 90k, should I replace my coolant expansion tank?

Thank you guys in advance.

 

I read that thread and am not convinced of the results/conclusions. Seems that maybe cleaning solenoids do the most good. You might trying swapping sensors from intake to exhaust and see if you notice any difference.

 

I wanted to give you guys an update.

I finally had my the engine maintance completed including VNOS solenoid cleaning and gasket/oring replaced, replaced all 4 camshaft sensors and all 8 coils.

Good news is that engine hesitation at low speeds is gone and torque curve is now almost even across RPMs. Given its not possible to know exactly which fix made the difference.