My check engine light keeps coming on in my 2007 760Li BMW. I bought it used in 2015 with 70,000 miles and the check engine light came on shortly after I bought it. I returned it to the dealer I bought it from who then took it to a BMW shop to diagnosed the problem as a "Fuel Mixture Adaptation" problem. When I got the car back the check engine light was not on so I assumed the problem was resolved. About a month later the check engine light came back on. I took it to my local BMW dealer and they said the same thing, that the problem was a "Fuel Mixture Adaptation" problem and they could not tell me how much it might cost to repair. They wanted to try to diagnose the problem without giving me any idea of how much it might cost. That was unacceptable to me so I looked for another solution. The car runs fine and I only use premium gas from brand name gas stations. But the check engine light continues to stay on and I want the problem fixed once and for all. I then found a local mechanic who specialize in foreign cars. He changed the spark plugs and did a smoke leak test and said he could not find a problem. My vacuum vent valves seemed to be in good shape. But the fault codes keep coming up as P2187 and P2189. He doesn't know how to fix this problem. Does anyone have a suggestion of how to resolve this problem?
The fault codes you are getting are saying you have mixture adaptation to lean on both banks at a idle condition. You have checked the basics meaning no intake leaks from using a smoke machine. There are tons of connections and places to leak so make 100% sure there are no air leaks. Second is to check the crankcase pressure and make sure it is in spec this can cause a lean condition if the vacuum is to high. Does the vehicle have any long cranking issues for idle kind of rough? There are issues with this engine on high pressure fuel pumps and injectors. Third thing to check is low pressure fuel pressure make sure it has a good fuel supply around 5.5bar.
Thanks for the feedback Charlson89, I really appreciate it. Regarding your question - "Does the vehicle have any long cranking issues or idle kind of rough?" - the answer is it has no cranking issues, but it idles bought sometimes, but not all the time. In the winter when it was cold it sometimes idled rough, but recently I had the plugs changed and since then it idles smoothly. I will have my mechanic check the fuel pressure and crankcase pressure.
