display AUDI A8 1998 D2 / 1.G AHA Engine Motronic Ignition System Workshop Manual

28-8

Knock sensor and knock sensor control,
checking


Required special tools and test equipment

VAG1551/1552 Scan Tool (ST) with
VAG1551/3 adapter cable
VAG1598/22 test box
Multimeter US1119 (Fluke 83 or equivalent)
VW1594 connector test kit
Wiring diagrams

Checking

- Connect VAG1551/1552 Scan Tool (ST) and
press buttons -0- and -1- to insert "Engine
Electronics" address word 01 (with engine
running at idle) page 01
-8 .
Rapid data transfer
HELP
Select function XX

Indicated on display
- Press buttons -0- and -8- to select "Read Measuring Value Block"
function 08, and press -Q- button to confirm input.
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Read Measurin
g Value Block
HELP
Input display group number XXX

Indicated on display
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28-9

- Press buttons corresponding to following display
group numbers and press -Q- button to confirm
input.


022: Display group 22, for cylinders 1 and
2

023: Display group 23, for cylinders 3 and
4

024: Display group 24, for cylinders 5 and
6
Read Measuring Value Block 22 1 2 3 4

Indicated on display (1-4 display groups)
Note:
The test must be carried out during a road test because the knock sensor
system is only active with engine speed greater than 2600 RPM and
engine load greater than 3 ms.
WARNING!
A second technician is required to operate the VAG1551 scan tool
during the road test. Safety precautions page 24
-9 .
- Road test and compare display with specified values for knock sensor
system in display field 1-4.
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28-10


Display fields

1 2 3 4
Display group 22 1): Knock control
Display xxx RPM xx.xx ms
xx.x
xx.x
Display Engine speed
(in 40 RPM
steps) Engine load Ignition angle correction 1 Ignition angle correction 2
Work range 0 - 6800 RPM 0.00 - 12.75
ms 0.0 - 12.0
(crankshaft)
0.0 - 12.0
(crankshaft)
Specified
Value ... RPM (test
drive) ... ms (test
drive) 0.0 - 10.0
(crankshaft)
0.0 - 10.0
(crankshaft)

--- --- If displayed values are NOT OK page 28
-11
, Evaluating display
groups 22, 23, 24
1) Display also valid for display groups 23 (cyls. 3 and
4) and 24 (cyls. 5 and
6) .
If displayed values are OK:

-
Press button.

- Press buttons -0- and -6- to select "End Output"
function 06, and press -Q- button to confirm
input.
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28-11
Evaluation of display groups 22, 23 and 24 Display groups: 22, 23 and 24
Possible malfunction
cause
Corrective action
Display fields: 3, 4


All cylinders retarded more than
10 (crankshaft)
Knock sensor faulty- Continuation page 28
-12

Connector corroded
Knock sensor
incorrectly torqued - Loosen knock sensor and tighten to 20 Nm (15 ft lb)
Components loose on
engine - Tighten components
Poor fuel quality- Change fuel
Value for one cylinder different
from the others Connector corroded- Continuation page 28
-12

Engine damage- Check compression Repair Manual, 2.8 Liter V6 5V
Engine Mechanical, Repair Group 15

Components loose on
engine - Tighten components
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28-16

Misfire recognition, checking


Required special tools and test equipment

VAG1551 or VAG1552 Scan Tool (ST) with
VAG1551/3 adapter cable

Checking

- Connect VAG1551/1552 Scan Tool (ST) and
press buttons -0- and -1- to insert "Engine
Electronics" address word 01 (with engine
running at idle) page 01
-8 .
Rapid data transfer
HELP
Select function XX

Indicated on display
- Press buttons -0- and -8- to select "Read Measuring Value Block"
function 08, and press -Q- button to confirm input.
Read Measuring Value Block
HELP
Input displa
y group number XXX

Indicated on display
- Press buttons -0-, -1- and -4- to input display group number 14 (014),
and press -Q- button to confirm input.
Read Measuring Value Block 14 1 2 3 4

Indicated on display (1-4 display groups)
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28-17

- Compare displayed values with specified values
for misfire recognition (display fields 3-4):

Display groups

1 2 3 4
Display group 14: Misfire recognition
Display xxx RPM xx.xx ms xxx activated
deact
Indicates Engine speed
(in 40 RPM
steps) Engine load Misfire harmful to emissions (total) Misfire recognition status
Range 0 - 6800 RPM 0.00 - 12.75
ms --- ---
Specified
value 620 - 740 RPM
(all-wheel drive) 1.0 - 2.5 ms 30 activated
740 - 860 RPM
(front-wheel
drive)

--- --- If displayed values are NOT OK page 28
-18
, display groups 15,
16
If displayed values are OK:
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28-18
If displayed values are NOT OK:

- Press -C- button.

- Press buttons -0-, -1- and -5- to input display
group number 15 (015), and press -Q- button to
confirm input. Read Measuring Value Block 15 1 2 3 4

Indicated on display (1-4 display groups) - Compare displayed values with specified values for misfire recognition
(display fields 1-4):

Display groups

1 2 3 4
Display group 15: Misfire recognition
Display xxx xxx xxx activated
deact
Indicates Misfire harmful to
emissions, Cyl. 1 Misfire harmful to
emissions, Cyl. 2 Misfire harmful to
emissions, Cyl. 3 Misfire recognition
status
Range 500 500 500 ---
Specified
value 0 - 5 0 - 5 0 - 5 activated

If displayed values are NOT OK page 28
-20
, Evaluation of display groups 15 and 16
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28-19
If displayed values are OK:

- Press -C- button.

- Press buttons -0-, -1- and -6- to input display
group number 16 (016), and press -Q- button to
confirm input. Read Measuring Value Block 16 1 2 3 4

Indicated on display (1-4 display groups) - Compare displayed values with specified values for misfire recognition
(display fields 1 and 4):

Display groups

1 2 3 4
Display group 16: Misfire recognition
Display xxx xxx xxx activated
deact
Indicates Misfire harmful to
emissions, Cyl. 4 Misfire harmful to
emissions, Cyl. 5 Misfire harmful to
emissions, Cyl. 6 Misfire recognition
status
Range 500 500 500 ---
Specified
value 0 - 5 0 - 5 0 - 5 activated

If displayed values are NOT OK page 28
-20
, Evaluation of display groups 15 and 16
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28-20
Evaluation of display groups 15 and 16 Display groups: 15
and 16


Display fields: 2 and
3
Possible malfunction cause
Corrective action
greater than 5

Ignition coil faulty
Spark plug connector faulty
Spark plug faulty
Power output stage for
ignition coil faulty - Check ignition coils -N-, -N128- and -N158- with power output
stage -N122 page 28
-21



Fuel injector faulty
Not enough fuel- Check fuel injectors page 24
-102
- Check fuel in tank
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