Testing modulating piston movement sender -G149 and quantity adjuster -N146 — AUDI

AHU
The quantity adjuster is an electro-magnetic swivelling positioner which is controlled by the control unit via a directed duty cycle (on-off ratio). The eccentric shaft on the quantity adjuster moves the modulating piston on the high pressure piston and thereby regulates the quantity of fuel injected.

The modulating piston movement sender informs the control unit of the position of the modulating piston, thereby indicating the quantity of fuel injected.

Special tools, testers and auxiliary items

Hand multimeter V.A.G 1526 or V.A.G 1526 A
Fault reader V.A.G 1551 (or vehicle system tester V.A.G 1552) with cable V.A.G 1551/1
Adapter set V.A.G 1594 A
Test box V.A.G 1598/18

Testing operation

Connect fault reader V.A.G 1551 and select engine electronics control unit => Page
01-2
.
Read measured value block, Display Group 001, engine at idling speed => Page
01-71
.

Read measured value block 1
"
840 rpm
5.6 mg/H
1.480 V
87.3 5C
Indicated on display:

Check display in display zone 4 (coolant temperature).
Specification: at least 85°C

Do not proceed with the test until the coolant temperature has reached the specified level.
Switch off any electrical consumers that may be on (air conditioner, rear window heater, lights etc.).

Read measured value block 1
"
840 rpm
5.6 mg/H
1.480 V
87.3 5C
Indicated on display:

Check display in display zone 3 (voltage supplied from modulating piston movement).
Specification: 1.250 ... 1.700 V

If the specification is not attained:

Fit a new injection pump => Page
23-19
.

Testing internal resistance

Switch off ignition.
Unplug connector for injection pump
=>Fitting locations overview, Page
23-3
, Item
4
.

Set hand-held multimeter V.A.G 1526 to resistance measuring range and connect it to the following contacts on the injection pump connector using test leads from V.A.G 1594 A:

Contact · To be tested · Specification
1 + 2 · -G149 · 4,9 ... 7,5 ω
2 + 3 · -G149 · 4.9 ... 7.5 ω
5 + 6 · -N146 · 0.4 ... 1.1 ω

If the specifications are not obtained, fit a new injection pump
=> Page
23-19
.

Testing voltage supply

Switch off ignition.
Disconnect connector on injection pump
=>Fitting locations overview, Page
23-3
.
Set hand-held multimeter V.A.G 1526 to voltage measuring range (20 V direct current).
Switch on ignition.

Connect hand-held multimeter to the following contacts on the wiring harness connector using test leads from V.A.G 1594 A:

Contact · To be tested · Specification
1 + earth · -G149 · approx. 2.5 V
3 + earth · -G149 · approx. 2.5 V
5 + earth · -N146 · approx. battery voltage

If the specifications are not obtained:

Check the wiring.

Testing wiring

With the ignition switched off, connect test box V.A.G 1598/18 to connector for engine control unit => Page
23-45
.

Test for open circuit and short to positive or earth in the following wiring connections:

Wiring harness / connector / Contact · Test box / V.A.G 1598/18 / Socket
1 · 29
2 · 7
3 · 52
5 · 23, 45, 68
6 · 4, 5, 49

Test all wires for short circuit to each other.
Rectify any open/short circuit as necessary.