Lean fuel condition could be caused by one of the following below: 1. Vacuum leaks
2. EGR and PCV valve.
3. Low fuel pressure.
4. Dirty fuel injectors.
5. Mass Air Flow Sensor.
6. Oxygen Sensor.
November, 27, 2010 AT 1:04 AM
No vacuum leaks, fuel pressure good, my scanner does not support european so can not get anything on mass air flow and bmw does not use egr they us A.I.R
November, 27, 2010 AT 4:17 AM
To find the root cause may require having BMW specific scanning equipment. What method did you employ to assure there are no vacuum leaks? What was the fuel pressure? Has the engine had cam timing checked? More history and a more detailed story of what has been done and how the car showed up at your shop might shed some light and would go a long way in our being able to help, otherwise we are in the dark here.
November, 27, 2010 AT 4:31 AM
Also, what coils are in the engine? The 2003 cars had lots of coil issues, pull one and describe it to me please, what color is it, is it Bosch or Bremi?