Resurrecting this thread since I am experiencing some of these same problems to a certain degree and already been busy replacing things without any change, annoyingly! I do feel that the BMS PBX aggravates these problems, but not cause them if that makes sense.
The biggest issue that I am having at the moment that I am trying to solve is the pinging or knocking between 1800 and 2500 rpm, mostly at moderate throttle inputs, but have noticed it on gear changes when driving a bit more spiritedly. So very annoying! And also have that dull performance drop off from 3000 - 4500 rpm before the power comes back like crazy! Hesitation has been there from day one and very irritating, and certainly not something that I would have expected from a BMW!
Today I tested something out (did something that I have indirectly trained myself not to do), I mashed the throttle while in 4th at around 60 - 80 km/h and get that sudden hesitation. Try it again soon after and it's fine, but let the car settle and maybe try 5th gear and again, mash the throttle and there's that somewhat violent hesitation.
Engine also feels lumpy to me - off throttle and there is an overrun jerk, then gently feed power back on and there is a slight jerk, so not the refinement that I want at all. Bought some Liqui Moly injector cleaner which I am going to try out and see, but I somehow doubt that this is going to help, and I am really now getting to the end of my patience with this car!
BMW E90 330i (M) '05 (His) | (Hers) BMW E46 320i f/l (M) '03