Audi Workshop Service and Repair Manuals

Test conditions

• ● No leaks in exhaust system
• ● Coolant temperature at least 80 °C (display group 4, display zone 3)
• ● Electrical consumers switched off (radiator fan must not run during the check)
• ● Air conditioner switched off
• ● Pressure gauge not connected
• ● Place selector lever in P or N position (vehicles with automatic gearboxes).

Checking idling speed

Notes:

• ◆ The idling speed cannot be adjusted.
• ◆ The idling speed is tested during the basic setting of the engine.
• ◆ During the basic setting of the engine, the air conditioner compressor is automatically switched off and the solenoid valve for the activated charcoal filter (ACC valve) is closed.

• ‒ Interrogate fault memory The fault memory must be clear. If necessary, rectify any faults and erase the fault memory. Switch off the engine, then start up again. Perform road test and interrogate the fault memory again to make sure it is clear.
• ‒ Leave engine idling.

• ‒ Press keys 0 and 4 for the function "Introduction of basic setting" and confirm entry with Q key.

• ‒ Press keys 0, 5 and 6 for "display group number 56" and confirm entry with Q key.

• ‒ Check whether the engine speed in the display zone 1 (actual speed) is within the permitted tolerance range (750 rpm...850 rpm).

Note:

• ◆ The engine speed in display zone 1 (actual speed) is the actual engine speed.
• ◆ The engine speed in display zone 2 (specified speed) is a theoretical value calculated by the engine control unit.
• ◆ See next page for further notes.

• ◆ During idling, the engine control unit always tries to adapt the actual engine speed to the specified engine speed.
• ◆ This means that during idling the actual engine speed must always approximate to the specified engine speed.
• ◆ The display zones three and four are there for information but are irrelevant for checking the engine idling speed.

• ‒ Press ⇒key.
• ‒ Press keys 0 and 6 for the "End output" function and press the Q key to confirm entry.
• ‒ If specification is not attained, interrogate the fault memory again.

If the idling speed is too high or too low and there are no faults recorded in the fault memory, carry out the following tests marked with a dot:

• ● Check intake air system for unmetered air .
• ● Check throttle valve control part .
• ● Solenoid valve for activated charcoal filter continuously open, check .
• ● Perform adaption of throttle valve control part .

Significance of 5-digit readout of display group 56