Mass air flow sensor
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Reference: WIS 07.07 Air Volume Gauge, Air Mass Gauge
Description - MAF
The Mass Air Flow (MAF) Sensor is also known as the Air Volume Gauge or Air Mass Gauge.
The MAF contains a hot wire sensor. For a complete description refer to:
http://en.wikipedia.org/wiki/Mass_flow_sensor
_Sensor.JPG)
This is what a MAF looks like courtesy of German Star.
Self Cleaning Function - MAF
One BenzWorld Member stated that the Bosch MAFs have a cleaning cycle. During this cycle, the current is briefly increased to the hot wire sensor and this increases the temperature to something like 1000F. This is akin to a self cleaning oven.
Issues - MAF
A commercial cleaner will remove oil and such deposits, but in the case of the Bosch MAF units, the deposit is probably more like a hard scale caused by deposits baking on.
DIY - Replace MAF
The following video shows how to replace the MAF housing:
The M-B designers knew that the MAF will foul over time and included programming that allows it to adapt to a changing reading. When this adaptation gets out of range, we get the typical mixture codes - such as P0170/3. Dealers apparently have the ability to check the degree of "adaption" whereas all we can read with our OBD II meters, is the codes.
DIY - MAF
It is possible to re-use your MAF housing and just buy the Bosch insert eg for $139 from Germanstar.net. That is the cheapest in the current market.
However the MAF is held in place with Torx Security Screws which have a dimple in the center of the screws and a special driver is needed.
See article on cleaning by BenzWorld Member Check Codes.
http://www.benzworld.org/forums/w210-e-class/1328069-maf-diy-pictorial-replacing-cleaning.html
There are heaps of other article on cleaning and replacing the MAF.
To Be Completed.