fuel pressure AUDI A4 1998 B5 / 1.G AWM Engine Motronic Injection System Servicing User Guide

24-45

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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24-46

- 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
ro replace front O-ring - pry O-ring off over
plastic cap).
Lightly lubricate O-rings with clean engine
oil.
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24-47

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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24-49

Test requirement:

Fuel pressure OK, checking Page 24
-32
.

Test sequence

- Remove fuel distributor including fuel injectors
from intake manifold Page 24
-45
. 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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24-51

- 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
-45
.

- If the measured values of all fuel injectors are
outside the specified range, check fuel pressure
Page 24
-32
.

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
-46
.
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24-68

Intake system, checking for leaks
(unmetered air)


Special tools and equipment

Notes:
Test sequence
VAS5051 with VAG5051/1Engine 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.
- Connect VAS5051 tester Page 01
-7 and select vehicle system "01 -
Engine electronics". Engine must run at idle for this.
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