1999 AUDI A6 ignition

24-1


Motronic fuel injection
system, servicing

Safety precautions

If special testing equipment is required during
road test, note the following:

WARNING!

Test equipment must always be secured to
the rear seat and operated from there by a
second person.
If test and measuring equipment is operated
from the passenger seat, the person seated
there could be injured in the event of an
accident involving deployment of the
passenger-side airbag.
To reduce the risk of personal injury and/or
damage to the fuel injection and ignition system,
always observe the following:
Only disconnect and reconnect wires for
injection and ignition system, including test
leads, when ignition is turned off.
If engine is to be cranked at starting RPM
without starting (e.g. for compression testing),
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disconnect connector from ignition coils and
from fuel injectors.
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24-2

It is possible that the control module will
recognize a malfunction and store a DTC during
some tests. After completing all tests and
repairs, DTC memory should therefore be
checked and erased if necessary. Readiness
code must be generated after DTC memory is
erased Page 01
-73
.

Always switch ignition off before cleaning
engine.
The battery should only be disconnected and
reconnected when the ignition is turned off,
since otherwise the Engine Control Module
(ECM) can be damaged.

WARNING!

Fuel system is under pressure! Before
opening system, place rags around the
connection point. Then release pressure by
carefully loosening connection.
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24-12


Repair Manual, 1.8 Liter 4
-Cyl. 5V Turbo Engine
Mechanical, Engine Code(s): AEB, ATW, Repair Group 21, Charge air system with turbocharger, checking

Repair Manual, 1.8 Liter 4
-Cyl. 5V Turbo Engine
Mechanical, Engine Code(s): AEB, ATW, Repair Group 26; Secondary Air Injection (AIR) system, checking
22 -
Fuel injectors -N30- through -N33- Checking Page 24
-38
Removing and installing Page 24
-46
23 -
Ignition coils -N-, -N128-, -N158-, -N163-
Checking Page 28
-4
24 -
Wastegate bypass regulator valve -N75-
Checking:
25 -
Mass Air Flow (MAF) sensor -G70-
Checking Page 24
-60
26 -
Secondary Air Injection (AIR) pump
motor-V101-
Checking:
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24-20

Special tools and equipment

Procedure
VAG1598/31
- Switch ignition off.
- Remove Engine Control Module (ECM) Page 24
-23
.

- Connect VAG1598/31 test box to connector of wiring harness. Ground
(GND) clip at test box (not visible in illustration) must be connected to
Ground (GND). Relevant test procedures note whether Engine Control
Module (ECM) should also be connected to the test box.
- Perform test as described in relevant repair sequence.
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24-23

Engine Control Module (ECM), replacing


Special tools and equipment

or
Removing
VAS5051 with VAG5051/1VAG1551 with VAG1551/3A
- Connect VAS5051 tester or VAG1551 scan tool and select control
module for engine electronics using "address word" 01 Page 01
-10
.
Ignition must remain switched on.
4B0906018Q
1.8 L R4/5VT
G 0008
Codin
g 07551
WSC 12345

VAG1551 Scan Tool (ST) display indicates control module identification,
e.g.
- Always allow display of control module identification first and print it out
Page 01
-13
.
- Compare coding with coding versions Page 01
-64
.
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24-24

- Switch ignition off.

- Pull off rubber seal of plenum chamber cover in direction of arrow.
- Remove cover -1- toward front.

- Remove Heater Core E-box cover (arrows).
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24-35


- 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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