Exhaust Gas Recirculation, Function; Networking Of The Electrical Components - Mercedes-Benz OM 471 Introduction Into Service Manual

Functions
GF14.20>W>3000H
ENGINES 471.9 in MODEL 963, 964
General information
The exhaust recycling (AGR) primarily serves to reduce the amount
of nitrogen oxides to comply with the emission limits even before
aftertreatment of the exhaust.
The suctioned in or supercharged fresh air is mixed with exhaust
so that the concentration of oxygen in the combustion mixture
reduces.
If the concentration of oxygen reduces the combustion
temperature drops which leads to reduced output of nitrogen
oxides (NOx).
System components
1 Exhaust gas recirculation cooler
2 Turbocharger
3 Exhaust manifold center part
4 Control lever
5 Throttle valve
6 EGR line (cold)
7 Charge air pipe (mixer housing)
8 Charge air housing
9 EGR line (hot)
10 Exhaust pipe
Y621 Exhaust gas recirculation positioner
A Intake air from air filter
B Charge air to charge air cooler (hot)
C Charge air to charge air cooler (cold)

Networking of the electrical components

A4 Engine management (MCM) control unit
B608 Charge air pressure and temperature sensor in charge air
pipe
B617 Charge temperature sensor in charge air housing
B621 Exhaust gas recirculation (AGR) differential pressure sensor
Y621 Exhaust gas recirculation positioner
66

Exhaust gas recirculation, function

– This printout will not be recorded by the update service. Status: 09 / 2011 –
The ratio of the recycled quantity of exhaust and suctioned in or
supercharged fresh air must be exactly regulated at all points in
time since the EGR (EGR) is active over the whole range of
rotational speeds. For a combustion mixture with an excessively
high proportion of exhaust deteriorates the combustion and the
emission of soot particles, carbon monoxide (CO) and
hydrocarbon (HC) increases. On the other hand the emission of
nitrogen oxides (NOx) increases if the ratio of fresh or
supercharged air is too high.
2.8.11
W14.20>1028>76
W14.20>1027>81