Mass air flow sensor: Difference between revisions

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==Description==
The Mass Air Flow (MAF) sensor is also known as the air volume gauge or air mass gauge.


Reference: WIS 07.07 Air Volume Gauge, Air Mass Gauge
The MAF contains a hot wire sensor and an integrated temperature sensor. For a complete description refer to: http://en.wikipedia.org/wiki/Mass_flow_sensor
==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:
This is what a MAF sensor looks like:
{|
|[[File:W220_BOSCH_mass_air_flow_MAF_sensor_F00C2G2025.jpg|thumb|none|W220 MAF sensor]]
|[[File:W220_MAF_sensor_Bosch_F00C2G2025.jpg|thumb|none|BOSCH MAF sensor (F00C2G2025)]]
|}


http://en.wikipedia.org/wiki/Mass_flow_sensor
The same sensor (BOSCH F00C2G2025) is used on both [[M112]] and [[M113]] engines. However, the inner diameter for the MAF housing on M112 is smaller (see the comparison below).


[[File:W220_Mass_Air_Flow_%28MAF%29_Sensor.JPG|300px|center]]
{|
|[[File:W220_MAF_sensor_housing_A1120940048_vs_A1130940048.jpg|thumb|none|MAF housing A1120940048 (M112) and A1130940048 (M113)]]
|[[File:W220_MAF_housing_A1120940048_vs_A1130940048.jpg|thumb|none|MAF housing M112 vs M113]]
|}


This is what a MAF looks like courtesy of German Star.
The MAF sensor will foul over time, but the [[mixture formation]] can workaround it by adapting the mixture formation. When this adaptation gets out of range, we get the typical mixture codes - such as P0170/3. The degree of "adaption" [[mixture formation|can be seen using DAS]].


[[File:W220_MAF_Sensor_Element_Courtesy_of_German_Star.JPG|300px|center]]
The sensor itself does not have MB part number and must be purchased together with the housing A1120940048 (for M112) or A1130940048 (for M113).
There are cheap 15 USD Chinese MAF sensors (e.g., sold on FENRIR parts store) that have proven to be reliable.


==Self Cleaning Function - MAF==
==Cleaning 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.
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==
To clean a MAF sensor, a special MAF sensor cleaner must be used, which leaves no deposit after drying out.
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.
A 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.
 
==Replacing MAF==
The MAF sensor is held in place in the MAF housing with two Torx security screws which have a dimple in the center of the screws and hence a special driver is needed.
 
[[File:MAF_Security_Torx_Screw_Driver.JPG|thumb|none|Torx security screw driver]]


==DIY - Replace MAF ==
The following video shows how to replace the MAF housing:
The following video shows how to replace the MAF housing:
{|
{|
|{{#ev:youtube|https://youtu.be/73rXBrisqsc|320|center|MAF Housing Relacement (By Masood)|frame}}
|{{#ev:youtube|https://youtu.be/73rXBrisqsc|320|center|MAF Housing Relacement (By Masood)|frame}}
|}
|}
 
<!-- http://www.benzworld.org/forums/w210-e-class/1328069-maf-diy-pictorial-replacing-cleaning.html -->
 
 
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.
 
[[File:MAF_Security_Torx_Screw_Driver.JPG|150px|center]]
 
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.

Revision as of 19:06, 15 July 2022

Description

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 and an integrated temperature sensor. For a complete description refer to: http://en.wikipedia.org/wiki/Mass_flow_sensor

This is what a MAF sensor looks like:

W220 MAF sensor
BOSCH MAF sensor (F00C2G2025)

The same sensor (BOSCH F00C2G2025) is used on both M112 and M113 engines. However, the inner diameter for the MAF housing on M112 is smaller (see the comparison below).

MAF housing A1120940048 (M112) and A1130940048 (M113)
MAF housing M112 vs M113

The MAF sensor will foul over time, but the mixture formation can workaround it by adapting the mixture formation. When this adaptation gets out of range, we get the typical mixture codes - such as P0170/3. The degree of "adaption" can be seen using DAS.

The sensor itself does not have MB part number and must be purchased together with the housing A1120940048 (for M112) or A1130940048 (for M113). There are cheap 15 USD Chinese MAF sensors (e.g., sold on FENRIR parts store) that have proven to be reliable.

Cleaning MAF

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.

To clean a MAF sensor, a special MAF sensor cleaner must be used, which leaves no deposit after drying out. A 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.

Replacing MAF

The MAF sensor is held in place in the MAF housing with two Torx security screws which have a dimple in the center of the screws and hence a special driver is needed.

Torx security screw driver

The following video shows how to replace the MAF housing:

Load video
YouTube
MAF Housing Relacement (By Masood)
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