Description of engine OM 607
54
Drive
b
Introduction of the New A-Class, Model Series 176
Exhaust gas recirculation (EGR)
The EGR reduces the nitrogen oxide (NO
x
) level in
the exhaust.
The oxygen (O
2
) concentration in the combustion
chamber is reduced here. The combustion temper-
ature is lowered due to reduction in the combustion
speed and through the higher heat capacity of the
recirculated exhaust in comparison to the intake
air.
The EGR is active from idle speed up to the upper
partial-load range. The EGR rate is determined rela-
tive to the engine load and engine rpm. The intake
and air temperature, exhaust temperature and
exhaust back pressure are also considered.
To do so, the CDI control unit in combination with
the drivetrain control unit reads in signals from the
following components:
• B2/5 Hot film MAF sensor
• Intake air temperature sensor
• Charge air pressure and temperature sensor
• Temperature sensor upstream of turbocharger
• Accelerator pedal sensor
• Exhaust back pressure sensor
• Crankshaft position sensor
• Exhaust flap controller actuator motor
• High-pressure exhaust gas recirculation
actuator
• Low-pressure exhaust gas recirculation actuator
P14.20-2334-00
Exhaust gas recirculation system, schematic
1 Charge air cooler
2 Exhaust gas recirculation cooler
3 Diesel particulate filter with oxidation catalytic
converter
4 Turbocharger
A Intake air (fresh air)
B Exhaust (low pressure)
C Exhaust (high pressure)
B2/5
Hot film MAF sensor
M16/6 Throttle valve actuator
M16/57 Exhaust flap controller
Y27/7
Low-pressure exhaust gas recirculation
actuator
Y27/8
High-pressure exhaust gas recirculation
actuator
– This printout will not be recorded by the update service. Status: 06 / 2012 –
