sensor AUDI TT 1998 8N / 1.G ATW Engine Motronic Fuel Injection Syst

24-16


Charge air pressure sensor -G31- (arrow) bolted into charge air cooler at
top Fig. 7 Installation location, charge air pressure sensor -G31-
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24-17


Air cleaner, disassembling and
assembling

1 -
Lower part of air cleaner housing
2 -
Sleeve
3 -
Rubber grommet
4 -
Air duct
to metering unit
5 -
Seal
6 -
Mass Air Flow (MAF) sensor -G70- Checking Page 24
-60
7 -
Air duct
8 -
6 Nm
9 -
Upper part of air cleaner housing
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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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24-60


Mass Air Flow (MAF) sensor -G70-,
checking

Special tools and equipment

VAG1526A
VAG1594A
VAG1598/31
VAS5051 with VAG5051/1
- or
VAG1551 with VAG1551/3A
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24-63
Evaluation display group 002 Display field:
3
Possible cause
Corrective action
less than 1.0
ms
Smaller values are only possible when driving in
deceleration mode
larger than 4.0
ms Engine under load due to power accessories.- Reduce load (A/C system/power
steering/generator)

Poor idle (does not run on all cylinders)- Check spark plugs.
- Check fuel injectors Page 24
-38
.


Throttle valve control module - J338- faulty- Check throttle valve control module
Page 24
-120

Display field:
4
Possible cause
Corrective action
smaller than
2.0 g/s
large false air mass between intake manifold and Mass Air
Flow (MAF) sensor
Voltage supply of Mass Air Flow (MAF) sensor or wire
connections to Engine Control Module (ECM) - Check intake system for leaks (false
air) Page 24
-68
.
- Check voltage supply and wire
connections Page 24
-64

larger than 4.5
g/s
Engine under load due to power accessories.- Reduce load (A/C system/power
steering/generator)

Voltage supply of Mass Air Flow (MAF) sensor or wire
connections to Engine Control Module (ECM) - Check voltage supply and wire
connections Page 24
-64

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24-64

Voltage supply for Mass Air Flow (MAF)
sensor, checking

Test requirements:

Fuse for Mass Air Flow (MAF) sensor OK

Electrical Wiring Diagrams, Troubleshooting &
Component Locations

Fuel Pump (FP) relay OK; checking Page 24
-53
.

Note:
Voltage is supplied to Mass Air Flow (MAF)
sensor from Fuel Pump (FP) relay.

- Disconnect connector from Mass Air Flow (MAF)
sensor.

- Connect multimeter for voltage measurement as follows.Harness connector
Terminal
Measure to
2 Engine Ground (GND)
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24-67

Check wire connections for Mass Air Flow
(MAF) sensor

Note:
Signal wire is also checked during wire test.

- 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 following wire connections for open circuit and short circuit to
Ground (GND) and B+: Harness connector
Terminal
VAG1598/31 test box
Socket
3 27
4 53
5 29
- Repair open circuit or short circuit if necessary.
- Also check all wires for short circuit to each other.
- Replace Mass Air Flow (MAF) sensor -G70-.
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