Checking modulating piston movement sender -G149 and metering adjuster -N146 — AUDI

AHU
Special tools and workshop equipment required

V.A.G 1526 A
V.A.G 1594 A
V.A.G 1598/18
VAS 5051 with VAS 5051/1 and VAS 5051/2

or

V.A.G 1551 with V.A.G 1551/1

The quantity adjuster is an electromagnetic rotary actuator which is activated by the control unit by means of a specific duty cycle. The eccentric shaft of the quantity adjuster moves the modulating piston on the high-pressure piston and thus determines the injection quantity.

The modulating piston movement sender is responsible for feedback of the position of the modulating piston to the engine control unit, i.e. it determines the injection quantity.

Test sequence

Reading measured value block 1
⇒
840 rpm
5.6 mg/S
1.480 V
87.3 5C
Read measured value block, Display group 001, engine idling
=> Page 01-72.
Check display in zone 4 (coolant temperature).
Specification: At least 85°C

Do not continue with test until coolant temperature has been attained.
If necessary, switch off ancillary loads (air conditioner, heated rear window, lights etc.).

Reading measured value block 1
⇒
840 rpm
5.6 mg/S
1.480 V
87.3 5C
Indicated on display:

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

If reading does not match specification:

Replace injection pump => Page 23-13.

Checking internal resistance

Switch off ignition.
Unplug connector at injection pump =>Exploded view of fitting locations, Page 23-4, item 5.

Connect up multimeter for resistance measurement as follows.

Contact · Testing of · Specification
1 + 3 · -G149 · 4.9 ... 7.5 ω
2 + 3 · -G149 · 4.9 ... 7.5 ω
4 + 7 · -N146 · 0.4 ... 1.1 ω

If readings do not match specifications, replace injection pump
=> Page 23-13.

Checking power supply

Switch off ignition.
Unplug connector at injection pump =>Exploded view of fitting locations, Page 23-4.
Switch on ignition.

Connect up multimeter for voltage measurement as follows.

Contact · Testing of · Specification
1 + earth · -G149 · approx. 2.5 V
2 + earth · -G149 · approx. 2.5 V
7 + earth · -N146 · approx. battery voltage

If readings do not match specifications:

Checking wiring

With ignition switched off, connect test box V.A.G 1598/18 to engine control unit connector => Page 23-40.

Check for open circuit and short to earth/positive in the following wiring.

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

Check all wires for mutual short circuit.
If necessary, eliminate open circuit in wiring/short circuit.