Expert: Don Berlan - 12/29/2009

Question
I have a problem with my '00 Z3 (M43 B19 - LG25045). Drives OK but after 6 driving cycles the EML comes on orange and Carsoft reports a P0171 error in the DME (fuel system too lean). The only other side effect is that when starting from cold, she will not idle and stalls until you blip the accelerator to about 2000rpm, then she idles fine. I get no other errors listed by Carsoft, which I would expect if it was a sensor problem. I have tried cleaning the MAS and have looked for vacuum leaks but cannot find anything obvious. Are there any common faults on the Zed that might be the cause?

Answer
The first step in a drivability concern would be to check the fuel pressure.This would cause many problems that are not code displayed.You mentioned cleaning the MAF but what of the throttle body?Another thing to remember is a codes is just a tool to help repair the fault,not give you the answer to the fault.The vehicles sensors have a"window" in which they operate,they have to exceed that window to set the light on.So although other codes for sensors doesn't appear,they still need to be checked.The O2 sensors are a common problem because they do seem to work the most and hardest.