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Discussion Starter · #1 ·
I ran the test in the instrument cluster and got 109 after three pulls in third gear. My left bank isn't reading the air that is coming in. I called a Mercedes approved dealer (they are 2 hrs closer than BMW) and explained my symptoms. He said if the Check Engine Light isn't on then the ECU isn't reading the air flow on that bank and the ECU is probably bad. He said that the O2 sensros should also chime in and trigger an SES light even if the MAFS didn't. Both MAFS are new and so are the O2 sensors. This guy has me nervous. I have the car scheduled with United BMW in Gwinette, GA on Thursday. I was just wondering what to expect. If I have to have a new ECU so be it. I don't want to be blind sided by such a $bill.
 

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I can speak for th ECU but my BMW garage have quoted me 800 euros for two new MAFS with labor.
 

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I ran the test in the instrument cluster and got 109 after three pulls in third gear. My left bank isn't reading the air that is coming in. I called a Mercedes approved dealer (they are 2 hrs closer than BMW) and explained my symptoms. He said if the Check Engine Light isn't on then the ECU isn't reading the air flow on that bank and the ECU is probably bad. He said that the O2 sensros should also chime in and trigger an SES light even if the MAFS didn't. Both MAFS are new and so are the O2 sensors. This guy has me nervous. I have the car scheduled with United BMW in Gwinette, GA on Thursday. I was just wondering what to expect. If I have to have a new ECU so be it. I don't want to be blind sided by such a $bill.
Forget what the MB dealer told you over the phone- that is a red herring.

We need the status of the car: what maintenance and work has been done. SOunds like there are NEW MAFs, correct? How long ago? Brand? Air Filter? HOw old, brand?

What else? Miles?

ECUs do not generally go bad... very rare

A
 

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Discussion Starter · #4 ·
2000 BMW M5 with 73k miles. All of the following have been added within 150 miles; New BOSCH spark plugs,2 new Mann air filters, BMW OEM BOSCH MAFS still worked fine, but also tried the BOSCH VW replacement, and new BOSCH O2 sensors. I ran the liter/kilometer test on the insturment panel and get 109's for three pulls in third gear. When I pull the spark plugs out they are very black and sooty after 100 miles of driving. If I unplug the left side MAFS the car stumbles, but when I unplug the right MAFS nothing happens. I took some starter fluid (ether spray) and looked for a vacuum leak. Nothing was found. No SES light is on. I tried to pull codes and still nothing came up. The SES light does work because it comes on when the key is in the ignition II position. I once thought that the condition was related to engine temp, but now have diagnosed otherwise. It is always present, even before and after the secondary air pump turns off. The engine temp seems to warm up to normal at almost 12:00 on the engine temp dial. Decrease in engine performance is only noticed under 2000 rpm's and exaggerated in 5th and 6th gears. I don't mind going to the dealer, but the nearest one is 2 hrs away one way. I simply don't have time to drive 4 hrs in a day, then repeat when fixed. Any suggestions would be greatly appreciated.:dunno:

Thanks
Jeff
 
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