With the total lack of input the controller does take remedial action. In some cases there is also a MAP sensor for back-up in others the fuel computation is made from the throttle switch.

With the defective part in the system poor reading are accepted although a correction program does repair them for the basic conditions to a limit. The 4-6000 rpm run usually catches a bad MAF as its not a normal condition and it is a condition where the value being monitored (air flow) is at the max.

Your car has probably the most compensation of any modern car. It can add up to 32% fuel to the normal mapped calculation. I worked on a 2003 Lexus this last week where the customer had spent $13k for a turbo kit with trans mods and the car consistantly pegged the fuel trims at idle (looked like a diesel). I verified the capabilities on the Lexus tech site and long term fuel trim was only 20%.

My 2000 BMW 540 only has available 25% fuel trim. Many others only have 15%. The 32% used in the late MBs will almost correct anything.

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Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician