fuel AUDI A4 1995 B5 / 1.G AWM Engine Motronic Injection System Servicing User Guide

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- Open shut-off valve of pressure gauge. The lever points in the direction
of flow.
- Start engine and let run at idle.
- Measure fuel pressure.

Specification: about 3.5 bar positive pressure

- Disconnect vacuum hose at fuel pressure regulator.

Fuel pressure must rise to about 4.0 bar positive pressure.
- Switch ignition off.
- Check for proper seal and residual pressure by observing pressure
drop on pressure gauge.
After 10 minutes, there must be at least 2.5 bar positive pressure
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If residual pressure sinks below 2.5 bar positive
pressure:

- Start engine and let run at idle.

If pressure does not drop now:
If pressure drops again:
If pressure does not drop now: - Wait until pressure has dropped, and then switch off ignition.
Simultaneously close shut-off valve of VAG1318 pressure gauge (lever
perpendicular to direction of flow -arrow-).
- Observe pressure drop on pressure gauge.
- Test check-valve on Fuel Pump (FP).
- Open shut-off valve of pressure gauge. The lever points in the direction
of flow.
- Start engine and let run at idle.
- Wait until pressure has dropped, and then switch off ignition.
Simultaneously clamp return line (with blue marking) completely
closed.
- Replace fuel pressure regulator
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If pressure drops again:

- Check wire connections, O-rings at fuel
distributor and fuel injectors for proper seal.

- Check whether pressure gauge is properly
sealed.

Note:
Before disconnecting pressure gauge, release
pressure by opening shut-off valve. Hold a
container in front of connection for this.
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Fuel injectors, checking

Special Tools and Equipment

VAG1526A
VAG1527B
VAG1594A
VAG1598/31
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Checking internal resistance

- Remove engine cover (arrows).
- Disconnect connector at the fuel injector to be tested.

If specified value is not obtained:
If specified value is obtained: - Connect multimeter at valve for resistance measurement.

Specification: 12 to 13 (at room temperature)
- Replace fuel injector.
- Check voltage supply
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Checking voltage supply

Test requirements:

Fuse for fuel injectors OK

Electrical Wiring Diagrams, Troubleshooting &
Component Locations

Fuel Pump (FP) relay OK; checking Page 24
-52
.

- Disconnect harness connector at the fuel
injector to be tested.

If LED does not light up: - Connect VAG1527B voltage tester as follows:Harness connector
Terminal
Measure to
1 Engine Ground (GND)
- Switch ignition on.

LED must light up.
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- Repair open circuit if necessary.
If LED lights up:

- Activation of fuel injectors, checking

Checking activation

Test requirement:

Internal resistance of valve OK

- Slide back rubber grommet of fuel injector
connector, but leave connector connected.

Note:
Voltage testers do not go out completely during low current pick-up
between activations by the ECM, but rather continue to glow a little and
then get slightly brighter during activation. - Connect VAG1527B voltage tester between sockets 2 (signal) and 1
(B+).
- Operate starter briefly (engine can also start).

LED must blink.
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If LED does not blink:

- Connect VAG1598/31 test box at wiring harness
to Engine Control Module (ECM), do not connect
ECM Page 24
-19
.

If wire connection is OK: - Check the following wire connections for open circuit and short circuit
to Ground (GND) and B+: Cylinder
Fuel injector harness connector
Terminal
VAG1598/31 test box
Socket
1 2 96
2 2 89
3 2 97
4 2 88
- Repair open circuit or short circuit if necessary.
- Replace Engine Control Module (ECM) Page 24
-22
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Fuel rail with fuel injectors, disassembling
and assembling

1 -
Fuel injector insert-3 Nm
use fluid securing material D 000 600 A2 to
insert.
2 -
O-ring Removing and installing Page 24
-45
Always replaceCoat with clean engine oil
3 -
Fuel injector Cylinder 1 Fuel Injector -N30-Cylinder 2 fuel injector -N31-Cylinder 3 fuel injector -N32-Cylinder 4 fuel injector -N33-Removing and installing Page 24
-45
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4 -
O-ring
Removing and installing Page 24
-45
Always replaceCoat with clean engine oil
5 -
Fuel distributor
6 -
Fuel supply line Tighten to 25 Nm
7 -
Fuel return line
8 -
Harness connector for injectors4x
9 -
Socket head bolt- 10 Nm
10 -
Fuel pressure regulator
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