engine AUDI A4 1998 B5 / 1.G AFC Engine On Board Diagnostic Multiport Fuel Injection Workshop Manual

01-185
Notes on display field 4
Display field 4 (learning requirement display) shows the learning range (display field 2) for which learning is required.
Requirement for learning:

No malfunction stored in DTC memory
Engine speed at idle 650-900 RPM and/or 1500-3000 RPM
Coolant temperature 80-110 C (176-230 F) (if learning does not start immediately after this requirement, step on the
throttle).
Learning is prohibited:

With uneven idle (hunting), during acceleration, at wide open throttle
If malfunctions are stored in the DTC memory (not with sporadic malfunctions)
If differences of 9% are obtained between the richest and leanest oxygen sensor learning value of one display group. If a
9% difference is obtained, continued learning of the learning range involved is discontinued. The learning requirement
display of this learning range can not be 1 display groups 005 and/or 006.
Learning starts 20 sec. after initiation of "Basic Setting" function 04 and/or 2 to 4 min. after each start at a which the coolant
temperature is less than 40 C (104 F). The following listing shows when the request for new learning (learning requirement) is forced:
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01-190
Test table display group 010 Display
fields Display on VAG 1551 scan tool
Malfunction cause
Malfunction repair
1/2 Difference between display value
1 (bank 1) and display value 2
(bank 2) greater than 8%
Spark plug faultyIntake air leak on one side Fuel injectors faulty - Repair cause
- Check DTC memory page 01
-13

and/or check fuel injectors page 24-
29


Heated Oxygen Sensor
(HO2S) faulty (dirty) - Check DTC memory page 01
-13

and/or display fields 3 and 4

Mechanical engine basic
setting (valve/camshaft
timing) not OK
Repair Manual, 2.8 Liter V6 2V
Engine Mechanical, Engine Code(s): AFC, Repair Group 13
- Check valve/camshaft timing
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01-191

Display
fields Display on VAG 1551 scan tool
Malfunction cause
Malfunction repair
3/4 Display does not fluctuate-constant
between 0.0 - 0.3 V and/or between
0.6 - 0.9 V
Fuel injector faulty- Check fuel injectors page 24
-29

Spark plug faultyLarge intake air leak Engine Coolant Temperature
(ECT) sensor -G62- faulty EVAP canister purge
regulator valve -N80- - Check spark plug
- Repair cause
- Check DTC memory page 01
-13

and/or check -G62-
- Check using output diagnostic test
mode page 01
-145
and/or check -
N80-

Heated Oxygen Sensor
(HO2S) -G39- faulty or dirty Oxygen Sensor (O2S) heater
-Z19- does not function - Check DTC memory page 01
-13

and/or check -G39-
- Check -Z19- page 24
-49

Fuel system pressure too
high or too low - Check fuel pressure regulator and
residual pressure page 24
-20


Constant 2.550 V Short to positive (B+) through:
Heated Oxygen Sensor
(HO2S) -G39- wiring Engine Control Module
(ECM) -J192- - Check -G39- page 24
-49Pa
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01-192

Display
fields Display on VAG 1551 scan tool
Malfunction cause
Malfunction repair
3/4
Constant value between 0.350 -
0.450 V Open circuit in:
Heated Oxygen Sensor (HO2S) -G39-
wiring Engine Control Module (ECM) -J192-- Check -G39- page
24
-49


Constant 0.000 V Short to ground in:
Heated Oxygen Sensor (HO2S) -G39-
wiring Engine Control Module (ECM) -J192-- Check -G39- page
24
-49


Notes on display field 4:
The display value at times must drop below 0.3 V
and exceed 0.6 V. Display values less than 0.40
V indicate lean condition; greater than 0.40 V
indicate rich condition.

HO2S voltage U (mV) vs. Lambda ( ) A - HO2S voltage (mV) high
Rich mixture (fuel excess or lack of air)
High CO value
B - Oxygen sensor probes voltage (mV) low
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01-193
Display group 011 Display
shows Specified display
value Designation
Basic setting
11
1 2 3 4 ... BTDC
1 = Ignition timing point without knock control and without idle speed control

... BTDC 2 = Ignition timing point with knock control and digital idle speed control (average
value for all cylinders)

_._ crankshaft 3 = Ignition timing point access to digital idle speed control
0 and/or 1 4 = Closed Throttle Position (CTP) switch function:
Open = 0; Closed = 1
Notes on display field 1:

At idle-Closed Throttle Position (CTP) switch closed-an ignition timing point of 12 BTDC is displayed. When the engine speed is increased-CTP switch open-the current ignition timing point is displayed without knock control
and without digital idle speed control.
Notes on display field 2:
Digital idle speed control is only active with Closed Throttle Position (CTP) switch closed.
Knock control is active starting at an engine load greater than 40% Display group 013 and/or 014.
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01-194
Display group 012 Display shows
Specified display value
Designation
Basic setting 12
1 2 3 4 ... RPM 1 = Momentary engine speed Display group 003, display field 1 ... % 2 = Momentary engine load Display group 003, display field 2 First map or second map 3 = Ignition timing point map switching

_._ crankshaft
4 = Ignition timing pt. retard by knock control (average of all cyl.)
Notes on display field 3:
The ignition timing point map switching is selected by knock control:

First map = Ignition timing point - basic map (98 octane)
Second map = Ignition timing point - map with reduced ignition angles (95 octane)
The ignition timing point difference between the first map and the second map is approx. 3 crankshaft. If an ignition timing
point retarded by approx. 4 crankshaft is recognized (display field 4), the second map is selected Display groups 013 and
014 for more exact evaluation.
The second ignition timing point map is selected:

If there is poor fuel quality (less than 95 RON)
If there are abnormal engine noises (subassemblies loose)
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If there is engine damage (oil burning because of faulty piston)
If a knock sensor malfunction is recognized in DTC memory, ignition map switching is blocked.
Notes on display field 4:
Knock control is active starting at an engine load greater than 40% Display groups 013 and/or 014. The ignition timing point retarding values are only used when knock control is "active."
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01-196
Display groups 013 and 014
Notes on display fields 2, 3 and 4:
Knock control is active starting at an engine load greater than 40%. If the engine load exceeds 40%, the current ignition timing
point retarding value is displayed; if the engine load drops below 40%, the last values used are displayed constantly.
If there is audible knocking without recognizable retarding of the ignition timing point, the engine speed should be increased
over 3500 RPM for 5 seconds to initiate the knock sensor malfunction recognition (On Board Diagnostic).
If an ignition timing point retarding value of one cylinder deviates from the others, the following malfunctions are possible:

Loose subassemblies
Corrosion on the harness connector
Engine damage (e.g. oil combustion with faulty piston)
If there are high ignition timing point retarding values on all cylinders of bank 1 or bank 2, the following malfunctions are
possible:
Corrosion on the harness connector display groups 015 and 016 Knock sensor tightening torque, 20 Nm (14 ft lb), not OK
Open circuit display groups 015 and 016 Knock sensor faulty
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01-197
Display group 015 Display shows
Specified display value
Designation
Basic setting 15
1 2 3 4 ___ RPM 1 = Momentary engine speed display group 003, display field 1 _._V 2 = Knock sensor signal (cylinder 1)
_._V 3 = Knock sensor signal (cylinder 2)
_._V 4 = Knock sensor signal (cylinder 3) Display group 016 Display shows
Specified display value
Designation
Basic setting 16
1 2 3 4 ___ RPM 1 = Momentary engine speed display group 003, display field 1 _._ V 2 = Knock sensor signal (cylinder 4)
_._ V 3 = Knock sensor signal (cylinder 5)
_._ V 4 = Knock sensor signal (cylinder 6)
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01-198
Display groups 015 and 016
Notes on display fields 2, 3 and 4:
If there is a difference of more than a factor of 3 between the lowest and the highest knock sensor signal in one display group,
the following malfunction is possible:

Corrosion on the harness connector
If there are differences of more than 50% in knock sensor signal between display group 015 (cylinders 1 to 3) and display
group 016 (cylinders 4 to 6), the following malfunctions are possible:
Corrosion on the harness connector
Open circuit
Knock sensor faulty
If no malfunctions are found during the electrical testing of the knock sensor, the wiring and the connections, the engine
should be checked for loose subassemblies or engine damage (e.g. oil burning due to faulty piston) Display groups 013
and/or 014.
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