sensor AUDI A6 1997 C5 / 2.G AHA Engine Multiport Fuel Injection And Ignition System User Guide

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
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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

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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

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24-24

- Check learning values for Oxygen Sensor (O2S)
control before TWC (display fields 1-4):

Display fields

1 2 3 4
Display group 32: Oxygen Sensor (O2S) control learning values (before TWC)
Display xx.x % xx.x % xx.x % xx.x %
Indicates O2S control learning
value at idle (additive)
(before TWC)
Bank 1, Sensor 1 O2S control learning value at
part load (multiplicative)
(before TWC)
Bank 1, Sensor 1 O2S control learning
value at idle (additive)
(before TWC)
Bank 2, Sensor 1 O2S control learning value at
part load (multiplicative)
(before TWC)
Bank 2, Sensor 1
Range -25.0 to +25.0 % -25.0 to +25.0 % -25.0 to +25.0 % -25.0 to +25.0 %
Specified
value -10.0 to +10.0 %
(can vary slightly) -10.0 to +10.0 %
(can vary slightly) -10.0 to +10.0 %
(can vary slightly) -10.0 to +10.0 %
(can vary slightly)
If not as specified Evaluation of display group 32, page 24
-27

If displayed values are OK (as specified):

- Press -C- button.

- Press buttons -0-, -3- and -3- to input display
group number 33, and press -Q- button to
confirm input.
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24-25

- Check Oxygen Sensor (O2S) control before
TWC (display fields 1-4):

Display fields

1 2 3 4
Display group 33: Oxygen Sensor (O2S) control (before TWC)
Display xx.x % x.xxx V xx.x % x.xxx V
Indicates O2S control
Bank 1, Sensor 1
(before TWC) O2S voltage
Bank 1, Sensor 1
(before TWC) O2S control
Bank 2, Sensor 1
(before TWC) O2S voltage
Bank 1, Sensor 1
(before TWC)
Range -25.0 to +25.0 % 0.000-1.000 V -25.0 to +25.0 % 0.000-1.000 V
Specified
value -10.0 to +10.0 %
value must change by
at least 2 % 0.000 to 1.000 V
value must fluctuate at least
30 times per minute, and
change by at least 0.3 volts -10.0 to +10.0 %
value must change by
at least 2 % 0.000 to 1.000 V
value must fluctuate at least
30 times per minute, and
change by at least 0.3 volts

If not as specified
page 24
-26
,
Continuation
If not as specified page 24
-
28
, Evaluation of display
group 33
If not as specified
page 24
-26
,
Continuation
If not as specified page 24
-
28
, Evaluation of display
group 33
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24-26

Continuation
If the value in either display field 1 or 3 is NOT
OK, or if the value does not fluctuate by at least 2
%:

- Road test to condition oxygen sensor(s)
(eliminate possible contamination) and repeat
test.
If the value in either display field 1 or 3 is still
NOT OK, or if it still does not fluctuate by at least
2 %:

- Check Oxygen Sensor (O2S) heater(s) page
24
-34
.
If the value in either display field 1 or 3 remains
constant:

- Check oxygen sensor voltage(s) (display fields 2
and 4).

-
Press button.
- Press buttons -0- and -6- to select "End Output"
function 06, and press -Q- button to confirm
input.

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24-27
Evaluation of display group 32 Display group:
32


Display fields:
1-4
Possible malfunction cause
Corrective action
O2S control
learning value:
-25.0 to -10.0
%
Engine oil dilution (when part load learning value is
normal display fields 2 and 4)
- Change engine oil, or carry out extensive
road test and check again


Fuel pressure too high- Check fuel pressure regulator page 24
-
111



Fuel injector leaking- Check fuel injectors page 24
-102


Oxygen Sensor (O2S) heater malfunction- Check O2S heater page 24
-34
O2S control
learning value:
10.0 to 25.0 %
Intake air leaks ("false air") or exhaust manifold leaks
(when partial load learning value is normal display
fields 2 and 4)
- Check intake air system for leaks page 24
-126

- Check exhaust system for leaks Repair
Manual, 2.8 Liter V6 5V General, Engine,
Repair Group 26


Fuel pressure too low- Check fuel pressure regulator page 24
-
111



Oxygen Sensor (O2S) heater malfunction- Check O2S heater page 24
-34
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Fuel injector does not open, or partially opens- Check fuel injectors page 24
-102
O2S control
learning value:
constant 0.0 %
Oxygen sensor control learning not active- Check Mass Air Flow (MAF) sensor -G70-
page 24
-68

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24-28
Evaluation of display group 33 Display group:
33


Display fields:
2, 4
Possible malfunction cause
Corrective action
approx. 0.435 V

Open circuit in wiring between HO2S connector terminal
4 and ECM - Check reference voltage page 24
-29
approx. 0.435 V

Open circuit in wiring between HO2S connector terminal
3 and ECM
approx. 1.085 V
Short circuit to positive (B+) between HO2S connector
terminal 4 and ECM - Check HO2S wiring, bank 1, sensor 1
page 24
-30

- Check HO2S wiring, bank 2, sensor 1
page 24
-32

approx. 0.000 V

Short circuit to Ground between HO2S connector
terminal 4 and ECM
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24-29

Checking HO2S reference voltage (Banks 1,
2)

- Disconnect 4-pin connector for respective
HO2S.

If voltage is NOT OK:
If voltage is OK: - Connect multimeter US1119 (Fluke 83 or equivalent) between harness
connector terminals 3 and 4 (to ECM), using adapter cables from
VW1594 connector test kit.
- Start engine and measure voltage.
Specified value: 0.40-0.50 volts
- Switch ignition off.
- Check HO2S wiring.

Bank 1, sensor 1 page 24
-30
.

Bank 2, sensor 1 page 24
-32
.
- Replace respective Heated Oxygen Sensor (HO2S).
Pa
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