Mercedes-Benz OM 904 LA, Руководство по эксплуатации

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Electronic engine control unit
The engine has a fully electronic management
system which, along with the engine and its
associated sensors, consists of the following
components:
R
engine control unit (MR)
R
drive control unit (FR) and/or other vehicle-
specific control units, e.g. adaptation mod-
ule (ADM)
R
exhaust gas aftertreatment control unit
(only for engines with BlueTec
®
exhaust
gas aftertreatment)
The control units are interconnected by a
CAN line (Controller Area Network line),
which facilitates the exchange of all neces-
sary data.
In addition to the engine and the BlueTec
®
exhaust gas aftertreatment, the electronic
engine control unit also monitors itself.
Depending on the malfunctions/failures that
occur, a safety and emergency mode
(
Y
page 8) may be automatically selected.
For vehicle engines, the electronic engine
control unit only allows the engine to be star-
ted when the transmission is in neutral.
Engine management control unit (MR)
(engine-mounted)
The engine management control unit (MR) is
on the left side of the engine.
Example: OM 926 LA engine management control
unit (MR)
The engine control unit (MR) processes val-
ues from the drive control unit (FR) and the
adaptation module (ADM). These are, for
example, the signal from the position sensor
(accelerator pedal), the engine brake or
engine start/stop, etc.
These values are analysed together with data
from the engine sensors. They are compared
with the charts or characteristic curves
stored in the engine management (MR) con-
trol unit.
Data from the sensors derives from informa-
tion such as:
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charge-air pressure and charge-air temper-
ature
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coolant temperature
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fuel temperature
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oil pressure
Start of injection, injection duration and injec-
tion quantity are calculated on this basis and
the unit pumps are controlled via the solenoid
valve accordingly.
If BlueTec
®
exhaust gas aftertreatment is
available, the associated sensors are also
analysed and the AdBlue
®
/DEF dosage is
controlled.
i
To obtain a replacement engine manage-
ment (MR) control unit, you will require all
the data on the control unit type plate.
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General information
At a glance