DAF XF105. Manual - part 93

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 200528

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Description of components

DMCI ENGINE MANAGEMENT SYSTEM

XF105 series

When the coil is deactivated by the electronic 

unit, the valve is pushed up again by the spring 

and the opening to the fuel gallery is released 

again. This stops the supply of fuel to the injector. 

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DMCI ENGINE MANAGEMENT SYSTEM

2-22

©

 200528

Description of components

XF105 series

Every pump unit is calibrated after production to 

compensate for any inaccuracies/differences in 

production. There is a 4-letter calibration code on 

the housing of the electrical connections. The 

code must be programmed into the electronic unit 

so that the unit can optimise controls for fuel 

injection. If the pump unit is replaced or moved, 

the calibration code must be programmed into the 

electronic unit again using DAVIE XD.

1621297

00000FMFM

SN 03030209

FMFM

30209

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©

 200528

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Description of components

DMCI ENGINE MANAGEMENT SYSTEM

XF105 series

2.12 INJECTOR

General

The pump unit supplies fuel to the injector. The 

injector consists essentially of two parts. The top 

part is a metal housing (1), to which the electrical 

connector (7) is attached. The coil (10) and spring 

(9) that open and close the valve (11) are also in 

the housing. The bottom part bears the closest 

resemblance to a conventional injector. The valve 

(11) and its guide are in this part, the nozzle 

holder (4). Below this are the plunger (12) and 

spring (13) and finally the nozzle (6), with the 

injector needle (14) inside. The copper washer 

(5) is under the nozzle holder.

The fuel enters the injector via the supply (A), in 

which the bar filter (8) is pressed. The return fuel 

leaves the injector via the opening (B) and flows 

into the cylinder head return duct.

7

A

8

9

10
11

12

13

14

6

5

4

3

2

1

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B

A.

Fuel supply

B.

Return opening

1.

Injector body

2.

O-ring

3.

O-ring

4.

Nozzle holder

5.

Washer

6.

Nozzle

7.

Electrical connection

8.

Bar filter

9.

Spring

10.

Coil

11.

Valve

12.

Plunger

13.

Plunger spring

14.

Injector needle

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DMCI ENGINE MANAGEMENT SYSTEM

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©

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Description of components

XF105 series

Electrical control
The injector is activated with a voltage of 

approximately 50V. This voltage is the discharge 

from a capacitor in the DMCI electronic unit. The 

current increases rapidly because of this 

relatively high voltage. As a result, the valve in the 

injector opens quickly. This is the pick-up phase. 

If the current were not limited, it would become 

too high and damage the coil in the injector. The 

increase in the current is limited by switching to 

pulsating control of approximately 24V after 

discharging the capacitor. This is the withstand 

phase. The current now remains high enough to 

hold the valve open. The length of the pick-up 

phase stays practically the same under all 

circumstances. The length of the withstand phase 

will vary depending on the calculations carried 

out by the electronic unit. When the pump unit is 

deactivated a negative induction peak is created 

by switching off the current through the injector 

coil. 

Operation
In the rest position, the valve is pushed down by 

the spring above the valve. The opening to the 

return is now closed.

U (V)

60

40

20

  0

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