Audi Workshop Service and Repair Manuals

Display Group 011 - Fuel consumption:

Display Group 012 - Knock control:

Display Group 013 - Knock control:

Display Group 014 - Knock control:

Display Group 015 - Knock control:

Notes on display groups 012, 013, 014 and 015:

• ◆ The knock control operates at engine loads of 40% or more.
• ◆ At engine loads of more than 40% the display will show the current (instantaneous) ignition timing retardation values. At engine loads of less than 40% the display will show the last values used (constant readout).
• ◆ If there is audible knocking and no perceptible ignition timing retardation, increase the engine speed to above 3500 rpm for 5 seconds in order to activate the knock sensor fault recognition (diagnosis) function.
• ◆ If there is a significant difference between the ignition timing retardation value for one of the cylinders and the values for the other cylinders, the following faults are possible:

- Loose ancillaries

- Corrosion on plug connector

- Engine damage (e.g. oil burning because of defective piston)

• ◆ If the ignition timing retardation values for all the cylinders are high, the following faults are possible:

- Corrosion on plug connector

- Wrong tightening torque (should be 20 Nm)

- Open circuit in wiring

- Knock sensor defective

- Loose ancillaries

- Poor-quality fuel (less than RON 95)

Display Group 016 - Knock control:

Notes on display group 016:

• ◆ To prevent engine damage the knock control must retard the ignition timing as soon as pinking is recognised.
• ◆ Retarding the ignition will though increase the exhaust gas temperature. There is a danger that the catalyst will overheat.
• ◆ To prevent this overheating, the mixture is enriched to lower the exhaust gas temperature when the total retardation of approx. 10°cr/shaft is reached at full throttle.

Display Group 017 - Knock sensor:

Display Group 018 - Knock sensor:

Notes on display groups 017 and 018:

• ◆ If no faults are found when testing the knock sensor, the wiring and the connectors, check the engine for loose ancillaries or engine damage (see display groups 012, 013, 014 and 015).
• ◆ At high engine speeds the displayed signal voltage for the knock sensors can reach 5.1 V.
• ◆ If there is more than 50 % difference between the smallest and largest knock sensor signals, the cause could be corrosion on the connector.

Display Group 019 - Torque reduction (automatic gearbox):

Notes on display group 019:

• ◆ This display group is used to check how the retardation of the ignition timing reduces the engine torque and thereby minimises jerky gear shifts.
• ◆ Due to the very short signals the retardation of the ignition timing is not always detected and therefore not displayed on V.A.G. 1551/1552.
• ◆ The engine torque required for the gear shift (specified torque) is shown in display zone 3.
• ◆ The actual engine torque (clutch torque/actual torque) is shown in display zone 4
• ◆ Checking ignition timing retardation during gear shift

Display Group 020 - Operating conditions:

Note on display zone 3:

• ◆ A/C-High = "idling speed increase" function active
• ◆ A/C-Low = "idling speed increase" function not active
• ◆ On vehicles with front-wheel drive the display will always show "A/C-High".
• ◆ On vehicles with four-wheel drive the idling speed is increased when the battery voltage is low.

Display Group 021 - Operating conditions for Lambda control:

Notes on display group 021:

• ◆ At a starting temperature of below 15 °C (intake air temperature) the engine control unit will not switch the Lambda control on until a coolant temperature of 55 °C is reached.
• ◆ For a starting temperature above 15 °C (intake air temperature) the Lambda control will commence functioning when the probes are recognised as being operationally ready.
• ◆ If the Lambda control is switched off the engine runs controlled by the engine map.

Display Group 022

This display group is for factory use only.

The display values are not relevant for fault-finding in the workshop.

Display Group 023 - Adaption of throttle valve positioner:

Note on display zone 1:

If the display does not show the specified value, perform adaption of throttle valve control part -J338.

Note on display zone 2, 3 and 4:

The display will show the stop values learned at the last basic setting.

Note on display zones 1, 2, 3 and 4:

If the display still does not show the specified value even after the basic setting has been performed, check the wiring for open circuits or short circuits and also check the plug connections for dirt or corrosion before fitting a new throttle valve control part.

Significance of figures in 8 digit number block, display zone 1 - Learning requirements display

Display Group 024 - Traction control system (ASR):

Notes on display group 024:

• ◆ Display group 024 is only relevant for vehicles with traction control system (TCS).
• ◆ Vehicles with traction control system can be recognised by the TCS warning lamp in dash panel insert or ABS/TCS self-diagnosis.

=> Running gear, Self-diagnosis; Repair group 01

When loss of traction is recognised, how the engine torque is reduced to prevent wheel spin can be assessed in this display group.

The engine control unit informs the ABS/TCS control unit of the current engine torque (actual torque). If wheel spin is recognised the required specified torque signal is calculated in the ABS/TCS control unit. This specified torque signal is forwarded to the engine control unit to reduce the torque. This torque reduction is broken down into 12 reduction stages. The ABS/TCS control unit receives the return information as to what extent the engine torque has been reduced, via the actual torque signal.

Notes continued:

• ◆ When the engine is cold (coolant temperature less than 30 °C) the engine torque reduction is achieved by:
  - Small reduction stages (1...2) by retarding the ignition timing.
  - Large reduction stages (3...12) by briefly switching off individual injectors.
• ◆ When the engine is warm (coolant temperature exceeds 45 °C) the engine torque reduction is achieved by briefly switching off individual injectors and by retarding the ignition timing.

Notes on display zones 3 and 4:

• ◆ Display zone 3 shows the required engine torque as calculated by the ABS/ASR control unit (specified engine torque).
• ◆ Testing specified engine torque signal from ABS/ASR control unit => Page 24-113.
• ◆ Display zone 4 shows the actual engine torque (torque at clutch).
• ◆ Testing signal for actual engine torque => Page 24-112.
• ◆ A distinctly higher value than the maximum 300 Nm possible from the engine will be shown in display zone 3 when the traction control system is not active, i.e. when no torque reduction is required from the traction control system. This is a purely theoretical value (up to 410 Nm) which is deliberately high in order to ensure that there is a definite "safety margin" compared with the actual torque available. This ensures that the engine control unit will recognise the demand to reduce the torque under all conditions.
• ◆ During the period where the traction control system is active the values in display zones 3 and 4 will come into a line with each other.

Display Group 025 - System status:

Display Group 026 - Camshaft timing control:

Display Group 027 - System status and camshaft timing control:

Note on display zone 1:

The display shows which systems are being activated by the engine control unit (system status). If the operating conditions (e.g. engine load, engine speed) for a system are right, the control unit will activate the system. However, the fact that a system is being activated does not necessarily mean that it is operating correctly.

Significance of the figures in the 3 digit display, display zone 1 - System mode

Notes on display zones 3 and 4:

• ◆ There are only two positions for the adjustable camshaft, the normal position and the adjusted position.
  To bring the camshaft into the adjusted position, accelerate the vehicle in 1st gear from rest.
  Display zones 3 and 4 show the actual positions of the adjustable camshafts.
  When the camshaft adjustment function is active (see display zone 1), display zones 3 and 4 will show whether the camshaft positions have in fact been adjusted (feed-back signal).
  -Camshaft in normal position = -3.0...+6.0°cr/shaft
  -Camshaft in adjusted position = 16.0...25.0°cr/shaft
• ◆ If display zones 3 and/or 4 display a value between 6.0°cr/shaft and16.0°cr/shaftduring a road test, this means that the camshaft adjustment solenoid valves are directing the oil pressure to the mechanical camshaft adjusters in the normal way, but that the mechanical camshaft adjusters are unable to reach their end positions (e.g. because they are stiff).
• ◆ Testing camshaft timing control => Page 28-37.

Display Group 095 - Basic function:

Display Groups 096 and 097:

These display groups are for factory use only.

The display values are not relevant for fault-finding in the workshop.

Display Group 098 - Adaption of throttle valve control part:

Display Group 099 - Lambda control:

Notes on display zone 4:

• ◆ To assist fault-finding, the lambda mixture control function is de-activated when Display Group 099 is selected in "Basic setting" mode (function 04) and activated when it is selected in "Read measured value block" mode (function 08).
• ◆ The lambda mixture control function is automatically re-activated by exiting from function 04 "Basic setting".
• ◆ By pressing the keys 4 and 8 on the V.A.G 1551 it is possible to switch back and forth between function 04 "Basic setting" and function 08 "Read measured value block".