check engine AUDI A6 1998 C5 / 2.G ATQ Engine Ignition System Checking Owner's Manual

28-34

Check ignition angle retardation of the
individual cylinders

- Connect VAS5051 tester or VAG1551 scan tool
and select the control module for engine
electronics using "address word" 01 Page 01
-
9 .

Engine must run at idle for this.Rapid data transfer
HELP
Select function XX

When indicated on display:
- Press buttons -0- and -8- to select "Read Measuring Value Block" and
press -Q- button to confirm input.
Read Measuring Value Block
Q
Input displa
y group number XXX

When indicated on display:
- Press buttons -0-, -2- and -0- to select "display group number 020" and
press -Q- button to confirm input.
Read Measuring Value Block 20
1
2
3
4

When indicated on display:
- Check indication in all display fields.
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Display fields

1 2 3 4
Display group 022: Ignition -knock control in driving operation
Display xxxx/min xxx.x %
xx.x KW
xx.x KW
Indicated Engine speed
(RPM) Engine
load Ignition angle retardation cylinder 1
via knock control
Knock sensor control Ignition angle retardation cylinder 2
via knock control
Knock sensor control
Specified
value xxxx/min 12 to 100
% 0 to 12 KW
0 to 12 KW
Notes Evaluation Page 28
-40

Note:
The number values indicated in display fields 3 and 4 represent actual ignition angle retardation via knock control of cylinders
1 and 2. Ignition angle retardation occurs in KW (crankshaft degrees) toward retardation.
- Press -C- button.Read Measurin
g Value Block
Q
Input displa
y group number XXX

When indicated on display:
- Press buttons -0-, -2- and -3- to select "display group number 023" and press -Q-
button to confirm input.
Read Measuring Value Block 23
1
2
3
4

When indicated on display:
- Check indications in display field 3 and 4.
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Display fields

1 2 3 4
Display group 023: Ignition -knock control in driving operation
Display xxxx/min xxx.x %
xx.x KW
xx.x KW
Indicated Engine speed
(RPM) Engine
load Ignition angle retardation cylinder 3
via knock control
Knock sensor control Ignition angle retardation cylinder 4
via knock control
Knock sensor control
Specified
value xxxx/min 12 to 100
% 0 to 12 KW
0 to 12 KW
Notes Evaluation Page 28
-40

Note:
The number values indicated in display fields 3 and 4 represent actual ignition angle retardation via knock control of cylinders
3 and 4. Ignition angle retardation occurs in KW (crankshaft degrees) toward retardation.
- Press -C- button.Read Measurin
g Value Block
Q
Input displa
y group number XXX

When indicated on display:
- Press buttons -0-, -2- and -4- to select "display group number 024" and press -Q-
button to confirm input.
Read Measuring Value Block 24
1
2
3
4

When indicated on display:
- Check indications in display field 3 and 4.
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Display fields

1 2 3 4
Display group 024: Ignition -knock control in driving operation
Display xxxx/min xxx.x %
xx.x KW
xx.x KW
Indicated Engine speed
(RPM) Engine
load Ignition angle retardation cylinder 5
via knock control
Knock sensor control Ignition angle retardation cylinder 6
via knock control
Knock sensor control
Specified
value xxxx/min 12 to 100
% 0 to 12 KW
0 to 12 KW
Notes Evaluation Page 28
-40

Note:
The number values indicated in display fields 3 and 4 represent actual ignition angle retardation via knock control of cylinders
5 and 6. Ignition angle retardation occurs in KW (crankshaft degrees) toward retardation.
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Evaluation display groups 020/021/022/023/024 - ignition angle retardation
Indicated on display
Possible cause
Corrective action
All cylinders more than 12 KW
Knock sensor faulty- Check knock sensor Page 28
-41

Harness connector corroded
Knock sensor incorrect
tightening torque - Loosen knock sensors and tighten to 20
Nm
Engine accessories loose- Secure engine accessories
Poor fuel quality- Change fuel quality
(see operating instructions)
One cylinder deviates significantly from
the others Harness connector corroded- Check knock sensor Page 28
-41

Engine damage
Repair Manual, Engine Mechanical,
Repair Group 15 - Check compression pressure:

Engine accessories loose- Secure engine accessories
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Component location Overview of Component
Locations, page Page 24
-5

Notes:

Knock Sensor (KS) 1 -G61- and Knock Sensor
(KS) 2 -G66- themselves cannot be electrically
tested.
Use only gold-plated terminals when servicing
harness connector for knock sensors.
For the knock sensors to function properly, it is
important that tightening torque be exactly 20
Nm.
Check harness connector from knock sensor to
wiring harness for corrosion.

Check knock sensors

Note:
Coolant reservoir screws must be removed and coolant reservoir must be
placed to side in order to access harness connector for knock sensor for
bank 2. The coolant hoses can remain connected. - Disconnect the harness connector of the relevant knock sensor in
engine compartment.
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Check wires from knock sensors to Engine Control Module (ECM). - Check all three terminals at knock sensor connector for short circuit to
each other (terminal 1+2, 1+3, 2+3).

Specification: (no continuity) - the wires must not have any
connection to each other.
- If there is no connection , replace knock sensor.
- If no short circuit is detected, check knock sensor wires:
- Connect VAG1598/31 test box at wiring harness to ECM, do not
connect ECM Page 24
-17
.
- Check the following wire connections for open circuit and short circuit
to Ground (GND) and B+:

Knock Sensor (KS) 1 -G61- Harness connector
Terminal
VAG1598/31 test box
Socket
1 (signal) 106
2 (Ground -GND-) 99
3 (shielding) 108
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Component location Overview of Component
Locations, page Page 24
-5

Notes:

Camshaft Position (CMP) Sensor -G40- is
located at rear of left cylinder block (bank 2).
Camshaft Position (CMP) Sensor 2 -G163- is
located at front of right cylinder block (bank 1).

Checking activation

- Slide back rubber grommet at connector of the
respective Camshaft Position (CMP) Sensor
(connector remains connected to Camshaft
Position (CMP) Sensor).

Note:
Connector socket numbers are shown on the rear side of the connector. - Connect VAG1527B voltage tester between sockets 2 (CMP sensor
signal) and 1 (B+).
- Operate starter for a few seconds.

LED must blink briefly at every second engine rotation.
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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 significantly brighter during activation.
If LED does not blink:

Checking voltage supply

- Disconnect connector at respective Camshaft
Position (CMP) sensor.

- Switch ignition on.

- Connect multimeter for voltage measurement as follows:Harness connector
Terminal
Measure to
1 Engine Ground (GND)

Specification: about 5 V
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Checking signal wire

Checking Ground (GND) wire
If all specified values are being reached and the LED does not blink
(measured between terminal 1 and 2 with starter and connector
connected): - Connect multimeter for voltage measurement as follows:Harness connector
Terminal
Measure to
2 Engine Ground (GND)

Specification: approx. battery voltage
- Connect multimeter for voltage measurement as follows:
Harness connector
Terminal
Measure to
3 B+

Specification: approx. battery voltage
- Repair open circuit or short circuit if necessary.
- Replace respective Camshaft Position (CMP) sensor.
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