AUDI A8 1998 D2 / 1.G AHA Engine Multiport Fuel Injection And Ignition System Owner's Manual

24-16

Idle speed, checking


Notes:

Idle speed, ignition timing and CO-content
cannot be adjusted.
Idle speed is maintained by the Throttle valve
control module.
CO-content is maintained and adjusted by
Oxygen Sensor (O2S) control. Malfunctions in
O2S control are recognized by On Board
Diagnostic (OBD) and stored in DTC memory.

Required special tools and test equipment
VAG1551 or VAG1552 Scan Tool (ST) with
VAG1551/3 adapter cable
Pa
ge 21 of 166 Motronic Multi
port Fuel In
jection
(MFI
) and i
gnition s
ystem
11/23/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU03.24.1

24-17

Test conditions

Fuses for engine electronics OK
No malfunctions stored in DTC memory
page 01
-16


Engine Coolant Temperature (ECT) at least
80 C (176 F)

All electrical consumers switched off
(radiator coolant fan must not run during
test)
A/C switched off
Exhaust system free of leaks
Automatic transmission selector lever in "P"
or "N" position
Throttle valve in Closed Throttle Position
(CTP); for Accelerator Pedal (AP) cable
adjustment Repair Manual, Fuel Supply
System, Repair Group 20
Pa
ge 22 of 166 Motronic Multi
port Fuel In
jection
(MFI
) and i
gnition s
ystem
11/23/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU03.24.1

24-18

Checking

- Connect VAG1551 or VAG1552 scan tool 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 -4- to select "Basic Setting" function 04, and
press -Q- button to confirm input.
System in Basic Settin
g
HELP
Input displa
y group number XXX

Indicated on display
- Press buttons -0-, -0- and -1- to input display group number 1 (001),
and press -Q- button to confirm input.
System in Basic Setting 1 1 2 3 4

Indicated on display (1-4 = display fields)
Note:
After selecting function 04, the ECM initiates the following:
EVAP canister purge regulator valve is closedA/C compressor is switched of
f
- Briefly raise engine speed (acceleration burst) and let engine run at idle
for another 2 minutes.
Pa
ge 23 of 166 Motronic Multi
port Fuel In
jection
(MFI
) and i
gnition s
ystem
11/23/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU03.24.1

24-19

- Compare display with specified values (display
fields 1-4):

Display fields

1 2 3 4
Display group 1: Engine idle speed
Display xxxx RPM
xx.x C
xx.x% xx.x %
Indicates Idle speed
(in 40 RPM steps) Engine Coolant
Temperature (ECT) Oxygen Sensor
(O2S) control, Bank
1 Oxygen Sensor
(O2S) control, Bank
2
Range 0 - 6800 RPM
-48.0 - 143.2 C
(-54 - 289 F)
-25.0 to +25.0 % -25.0 to +25.0 %
Specified
value 620 - 740 RPM
(all-wheel drive) 80.0 - 105.0 C
(176 - 221 F) -10.0 to +10.0 %
value must change by
at least 2 % -10.0 to +10.0 %
value must change by
at least 2 %
740 - 860 RPM
(front-wheel drive)

If not as specified Evaluation of
display group 1 page 24
-21

--- If not as specified:
- Check HO2S and O2S control before TWC
page 24
-22

Pa
ge 24 of 166 Motronic Multi
port Fuel In
jection
(MFI
) and i
gnition s
ystem
11/23/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU03.24.1

24-20
If displayed values are OK (as specified):

-
Press button.
- Press buttons -0- and -6- to insert "End Output"
address word 06, and press -Q- button to
confirm input.

- Check readiness code page 01
-70
. If
Diagnostic Trouble Code (DTC) memory has
been erased, or ECM was disconnected,
generate new readiness code page 01
-73
.

Note:
The increased idle speed for vehicles with front-
wheel drive is achieved if there is voltage (from
terminal 15er) supplied to terminal 10 of the
Engine Control Module (ECM).
Pa
ge 25 of 166 Motronic Multi
port Fuel In
jection
(MFI
) and i
gnition s
ystem
11/23/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU03.24.1

24-21
Evaluation of display group 1 Display
Group: 1


Display
field: 1
Possible malfunction cause
Corrective action
less than
620
(all-wheel
drive)
or
less than
740
(front-wheel
drive)
Driving mode engaged
Adaptation of throttle valve control module -J338- to
engine control module cannot be conducted
Throttle valve control module malfunction- Move selector lever into "P" or "N" position
- Carry out adaptation of throttle valve control
module -J338- to ECM page 24
-150

- Check -J338- page 24
-128
less than
740
(front-wheel
drive)
B+ (15) to terminal 10 of ECM missing- Check voltage supply to terminal 10 on ECM
per wiring diagram
greater than
740
(all-wheel
drive) Adaptation of throttle valve control module -J338- to
engine control module cannot be conducted
Closed Throttle Position (CTP) switch open
Throttle valve control module malfunction- Carry out adaptation of throttle valve control
module -J338- to ECM page 24
-150

- Check -J338- page 24
-128
Pa
ge 26 of 166 Motronic Multi
port Fuel In
jection
(MFI
) and i
gnition s
ystem
11/23/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU03.24.1

or
greater than
860
(front-wheel
drive)


Intake air leaks ("false air")- Check intake air system for leaks page 24
-
126

Pa
ge 27 of 166 Motronic Multi
port Fuel In
jection
(MFI
) and i
gnition s
ystem
11/23/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU03.24.1

24-22

Heated Oxygen Sensor (HO2S) and
Oxygen Sensor (O2S) control before
TWC, checking


Notes:

Connector for Heated Oxygen Sensor (HO2S)
before Three Way Catalytic Converter (TWC) -
G39- (bank 1, sensor 1): 4-pin, black.
Connector for Heated Oxygen Sensor (HO2S) 2
before Three Way Catalytic Converter (TWC) -
G108- (Bank 2, sensor 1): 4-pin, black.
Component location page 24
-1

Required special tools and test equipment

VAG1551 or VAG1552 Scan Tool (ST) with
VAG1551/3 adapter cable
VAG1598/22 test box
Multimeter US1119 (Fluke 83 or equivalent)
VW1594 connector test kit

Pa
ge 28 of 166 Motronic Multi
port Fuel In
jection
(MFI
) and i
gnition s
ystem
11/23/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU03.24.1

Wiring diagram

Test conditions
Engine Coolant Temperature (ECT) at least
80 C (176 F)
Pa
ge 29 of 166 Motronic Multi
port Fuel In
jection
(MFI
) and i
gnition s
ystem
11/23/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU03.24.1

24-23

Checking

- Connect VAG1551 or VAG1552 scan tool 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 Measurin
g Value Block
HELP
Input displa
y group number XXX

Indicated on display
- Press buttons -0-, -3- and -2- to input display group number 32 (032),
and press -Q- button to confirm input.
Read Measuring Value Block 32 1 2 3 4

Indicated on display (1-4 = display fields)
Pa
ge 30 of 166 Motronic Multi
port Fuel In
jection
(MFI
) and i
gnition s
ystem
11/23/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU03.24.1