Exhaust Gas Recirculation Rate Control; Influence On The Engine Braking System - Mercedes-Benz OM 471 Introduction Into Service Manual

Function

Exhaust gas recirculation rate control

The exhaust gas recirculation positioner (Y621) is actuated by a
PWM signal from the engine management (MCM) control unit
(A4).
During actuation a magnetic field is generated inside the coil
through which the mechanism is then actuated to deflect the
adjusting lever (10).
The adjusting lever (10) is connected to the throttle valve (4) in the
exhaust gas recirculation pipe (3) and it gradually rotates this
depending on the control signal from the engine management
(MCM) control unit (A4) so that more or less exhaust is branched
off towards the exhaust gas recirculation cooler.
i Introduction of engine OM 471 and exhaust aftertreatment > 09/2011 >
– This printout will not be recorded by the update service. Status: 09 / 2011 –
System components

Influence on the engine braking system

The exhaust gas recirculation positioner (Y621) is actuated in
certain circumstances by the engine management (MCM) control
unit (A4) to support the engine braking system. In interplay with
the waste gate valve of the turbocharger, this should help to
achieve an increase in the cylinder's internal pressure, which in
turn means that the upstroke piston is braked more powerfully,
and therefore the braking torque is increased.
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