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

28-1
Motronic ignition system Technical data, spark plugs

Engine code
AHA

Engine idle RPM

Idle RPM cannot be adjusted, is corrected by Idle Air Control (IAC) 620 - 740 RPM
(all-wheel drive)
740 - 860 RPM
(front-wheel drive)
RPM limit
Operates by shutting off fuel injectors approx. 6500 RPM
Ignition timing
Ignition timing cannot be adjusted; it is determined by the Engine Control Module (ECM)
Firing order 1-4-3-6-2-5
Spark plugs Tightening torque 30 Nm (22 ft lb)
Part No. 1) 101 000 035 HJ (NGK)
Manufacturer's code
(if applicable) BKR 6 EKUB (NGK)

Electrode gap - mm 1.6 mm

Maintenance interval Owner's Manual

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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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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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28-22

Checking

- Check DTC memory page 01
-16
.

There must be no malfunctions stored

- If DTC memory is not clear (malfunctions
recognized):

- Make necessary repairs and erase DTC
memory.

- Stop engine and start engine again.

- Road test.

- Check and erase DTC memory again.

- By briefly disconnecting fuel injector connectors
with engine running, check which cylinder is
misfiring, or not firing at all.
A misfiring cylinder can also be isolated by
examining the spark plugs (for a carbon-fouled
plug).

-
Interchange spark plug with one from cylinder
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28-25

Checking signal for power output stage

- Remove connectors from all 6 injectors (DTC
memory will have to be checked and erased
later).

- Switch ignition on.

If LED flashes: - Connect LED tester VAG1527 between engine ground and connector
terminal 3.
- Crank starter for several seconds.
LED in voltage tester must flash.
- Repeat test on 5-pin connector terminals 4 and 5.
- Replace ignition coils -N-, -N128- and -N158- with power output stage -
N122-.
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28-28

Checking voltage supply of ignition coils

Test requirement

Fuse for ignition coils OK

- Disconnect 5-pin connector from ignition coils.

- Switch ignition on.

If LED does not light up:
Electrical Wiring Diagrams, Troubleshooting & Component Locations
binder - Connect VAG1527 LED voltage tester between engine ground and
terminal 1 (B+) of connector.
LED in tester must light up.
- Check wires for open circuit per wiring diagram.
- Check fuse for ignition coils.
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