System Components; Exhaust Gas Recirculation (Egr); Ic Control Unit (Icuc) (A1); Fan Control - Mercedes-Benz OM 471 Introduction Into Service Manual

System components

Engine management for the Amplified Pressure Common Rail
System (APCRS)
The main task of the engine management (MCM) control unit (A4)
is to regulate injection of the Amplified Pressure Common Rail
System (APCRS).
All required data such as the output, diverse performance maps or
data which serves to protect the engine is stored in the engine
management (MCM) control unit (A4).
In order to regulate the injection which takes place through
appropriate actuation of the fuel injectors for cylinder 1 to 6
(Y608 to Y613) and the quantity control valve (Y642), the engine
management (MCM) control unit (A4) reads in signals from
virtually all sensors connected to it. This means: all information
except that from the engine oil fill level sensor (B605) is used in
the computations.
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Diesel particulate filter (DPF) > only for code (M5Z) Engine version
Euro VI
During the regeneration phase of the diesel particulate filter
(DPF) the engine management (MCM) control unit (A4) actuates
the fuel shutoff valve (Y629) and (in intervals) the fuel metering
valve (Y628).
The fuel shutoff valve (Y629) and the fuel metering valve (Y628)
are located together with the fuel pressure sensor (inlet) (B625)
and the fuel pressure sensor (outlet) (B626), in one metering
device. This ensures that diesel fuel is metered over a line to the
injection nozzle in the nozzle unit for DPF regeneration which is
located on the exhaust pipe upstream of the diesel particulate
filter (DPF).
The injection nozzle injects specific fuel amounts into the hot
exhaust flow. During the resulting reaction in the exhaust
aftertreatment unit, a great deal of heat is generated, in which
the soot deposited in the diesel particulate filter (DPF) is burnt to
form ash.
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Engine brake
According to a request from the drive control (CPC) control unit
(A3), the engine management (MCM) control unit (A4) actuates
the engine brake solenoid valve, stage 1 (Y624), the engine brake
solenoid valve, stage 2 (Y625) or both solenoid valves together.
Actuation of solenoid valves causes the engine oil to be fed to the
respective rocker arms with hydroelement. This means that the
respective brake rocker arms operate via the respective rocker arm
with hydroelement on an exhaust valve, whereby the engine
brake is active.
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– This printout will not be recorded by the update service. Status: 09 / 2011 –

Exhaust gas recirculation (EGR)

The fact that exhaust gas recirculation is active over the whole
rotational speed range means that the ratio between recycled
exhaust gas masses and suctioned in or supercharged fresh air
mass must be matched exactly and thus exactly regulated.
This relationship, the so>called exhaust gas recirculation rate, is
regulated by the engine management (MCM) control unit (A4)
through appropriate actuation of the exhaust gas recirculation
positioner (Y621).
The EGR rate value here is determined by the information from
the charge air pressure and temperature sensor in the charge air
pipe (B608), by the exhaust gas recirculation (EGR) differential
pressure sensor (B621) and by the charge air temperature sensor
in the charge air housing (B617), taking the data stored in a
corresponding characteristics map into account.
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IC control unit (ICUC) (A1)

To display this in the instrument cluster control unit (ICUC) (A1)
the engine management (MCM) control unit (A4) records the
engine oil level, the engine oil temperature, the engine oil
pressure, the coolant temperature and the engine rpm.
It also uses values from the following sensors:
Engine oil fill level sensor (B605)
f
f Oil pressure sensor (B604)
f Intake coolant temperature sensor (B607) or exhaust (B606)
f Crankshaft position sensor (B600)

Fan control

For fan regulation purposes the engine management (MCM)
control unit (A4) uses information from the coolant inlet
temperature sensor (B607) and the coolant outlet temperature
sensor (B606).
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Tasks covering a number of systems
These tasks include engine or system diagnosis, since almost all
electrical or electronic components which are attached to the
engine management (MCM) control unit (A4) can be diagnosed.