Vanos Check valves
 

So the E60 with N54 engine (175,000 miles) has been to 3 shops, they are not able to find a diagnosis for the P0174 P0171 lean codes it throw every time it is driven. Some days it will stumble bad and almost die at the first stop sign,.....then it is fine, just a little low rpm hesitation. So far, valves have been blasted, new valve cover (old one was very clean inside) new Blow-by vent hose, new spark plugs, new MAP and Boost pressure sensors, Vanos solenoids have been cleaned and positions swapped, (they were very clean prior to removal)

With how clean the engine is, I doubt that the vanos check valves are bad, but am thinking about pulling them next. Also thinking about replacing the vanos solenoids. Another forum recommended using the Vaico brand as they are more cost effective and a better unti than the BMW oem.

Anyone use these in the past? If so, what are your thoughts.

Thanks