fuel pressure AUDI A4 1998 B5 / 1.G ATW Engine Motronic Fuel Injection Syst

24-36
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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24-37
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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24-44


4 -
O-ring
Removing and installing Page 24
-46
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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24-45


Repair Manual, 1.8 Liter 4
-Cyl. 5V Turbo Engine
Mechanical, Engine Code(s): AEB, ATW, Repair Group 15; Cylinder head, removing and installing; Intake manifold, removing and installing
11 -
O-ring
Always replace
12 -
O-ring Always replace
13 -
Retaining clip For fuel pressure regulator
14 -
Retaining clip Make sure clip is correctly seated on fuel
injector and fuel rail
15 -
Intake manifold With throttle valve control module -J338-With Intake Air Temperature (IAT) sensor -
G42- Removing
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24-46

Fuel injectors, removing and installing


- Remove engine cover (arrows).
- Disconnect wiring/connectors at:
- Fuel injectors -N30-, -N31-, -N32-, -N33-
- Intake Air Temperature (IAT) sensor -G42-
- Camshaft Position (CMP) sensor 2 -G40-
- Throttle valve control module -J338-

- Remove retaining bolts for fuel supply rail and disconnect vacuum line
at fuel pressure regulator (arrows).
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24-47

- Disconnect fuel distributor with injectors from
intake plenum and set aside in rear of engine
compartment on a clean cloth.

WARNING!

Fuel system is under pressure! Before
opening system, place rags around the
connection point. Then release pressure by
carefully loosening connection.

- Disengage retaining clip and remove fuel
injector.

Note:
Fuel lines must be removed before replacing fuel
distributor.
Installation is reverse of removal, noting the
following:

Remove O-rings at all opened connections.
(Never remove plastic cap from valve head
to replace front O-ring - pry O-ring off over
plastic cap).
Lightly lubricate O-rings with clean engine
oil.
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24-48

Make sure fuel injectors are in place and
seated correctly
Check clip for unobstructed fitting.
Place fuel rail with secured fuel injectors
onto intake manifold, and apply uniform
pressure to press it in.

Tightening torque

Component

Nm
Fuel distributor at intake manifold 10
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24-50

Test requirement:

Fuel pressure OK, checking Page 24
-33
.

Test sequence

- Remove fuel distributor including fuel injectors
from intake manifold Page 24
-46
. Fuel lines
remain connected.

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

Checking Proper Seal

- Bridge terminals 1 and 65 at test box using wires
from VAG1594A adapter test kit.

- Switch ignition on.


Fuel Pump (FP) must run.

- Check proper seal of fuel injectors (visual
inspection). With Fuel Pump (FP) running, only 1
to 2 drops per minute may drip out per injector.

-
If fuel loss is greater, stop Fuel Pump (FP) from
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24-52

- After all four fuel injectors have been activated,
place measuring glasses on an even surface.


Specified value for each fuel injector: 135
10 ml

- If measured value of one or more fuel injectors
is outside of specified range, switch Fuel Pump
(FP) off (switch ignition off) and replace faulty
fuel injector Page 24
-46
.

- If measured values of all fuel injectors are
outside specified range, check fuel pressure
Page 24
-33
.

Note:
Also check spray pattern when checking injection
quantity. Spray pattern must be the same for all
injectors

- Install fuel injectors together with fuel distributor
Page 24
-47
.
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24-68

Intake system, checking for leaks
(unmetered air)


Special tools and equipment

Note:
VAS5051 with VAG5051/1
orVAG1551 with VAG1551/3AEngine leak detection spray G 001 800 A1The negative pressure in the intake system sucks in the leak detection
spray with the unmetered air. Leak detection spray decreases ignition
quality and performance of the fuel mixture. This causes a reduction in
engine speed and a sharp increase of CO content. It is absolutely necessary to follow the safety precautions listed on the
can.
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