Arrow Injector Quantity Compensation Code; Injection Without A Pressure Booster (4) - Mercedes-Benz OM 471 Introduction Into Service Manual

Location of the injector quantity compensation code, shown on
injection nozzle for cylinder 6 (Y613)
Y613 Cylinder 6 fuel injector

Arrow Injector quantity compensation code

All fuel injectors have a 6>digit code, the so>called injector quantity
compensation code (arrow) which is applied above the high
pressure feed point.
The code describes the quantity characteristics of the respective
fuel injector. If a fuel injector is replaced this must be reported to
the engine management (MCM) control unit (A4) over Star
Diagnosis.
Function
The fuel injectors are fitted with a pressure booster (4). This gives
rise to 2 injection variants:
f

Injection without a pressure booster (4)

f Injection with a pressure booster (4)
In the case of injection without pressure booster (4) the injection
pressure is determined by the rail pressure (about 900 bar).
In the case of injection with pressure booster (4) the injection
pressure of up to 2100 bar is generated in the fuel injector.
Use of the pressure booster (4) offers the following advantages:
f The leak oil losses in the high pressure area are reduced.
f The pressure load of the high pressure pump, the rail, the
high pressure lines as well as components in the fuel
injectors are countersunk since only few components have
the highest pressure applied to them.
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Injection without a pressure booster (4)
i The following description of the function of injection without
a pressure booster (4) is described using the cylinder 1 fuel injector
(Y608) as an example and can be applied to all other fuel injectors.
Schematic diagram of injection without a pressure booster (4),
shown on cylinder 1 fuel injector (Y608)
3 High pressure feed
4 Pressure booster
6 Spring
7 Nozzle needle
8 Check valve
9 Return spring
10 Fuel return for pressure booster
11 Fuel return for nozzle needle
Y608 Cylinder 1 fuel injector
Y608 y1 Cylinder 1 pressure booster solenoid valve
Y608 y2 Cylinder 1 nozzle needle solenoid valve
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
Therefore each injection nozzle is fitted with a second solenoid
valve. Taking the example of the cylinder 1 fuel injector (Y608),
this would be the solenoid valve for the pressure booster for
cylinder 1 (Y608 y1), over that for the pressure booster (4),
depending on the operating condition of the engine, which can
be actuated by the engine management (MCM) control unit (A4),
independently of actuation of the cylinder 1 nozzle needle
solenoid valve (Y608 y2).
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