With Manufacturer's Scan Tool

Idle Speed, Testing

Special tools and equipment






- VAS 5051 and VAS 5051/1

Requirements for test:
- Exhaust system free of leaks
- Coolant temperature at least 80 degree C
- Electrical consumers switched off (radiator fan must not run during the test)
- Air conditioner switched off
- No pressure gauge connected

NOTE:
- 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 solenoid valve for the evaporative emissions (EVAP) canister purge regulator valve -N80 is closed and the air conditioner compressor is automatically switched off.

Test sequence
- Connect the vehicle diagnostic, testing and information system VAS 5051, and select the vehicle system "01 - Engine electronics" from the menu. When doing this the engine should be idling. Connecting VAS 5051/VAG1551 Scan Tool
- Check Diagnostic Trouble Code (DTC) memory. The Diagnostic Trouble Code (DTC) memory must be clear. If necessary, correct any faults and erase the Diagnostic Trouble Code (DTC) memory. Switch off the engine, then start up again. Take vehicle for a test drive and check the Diagnostic Trouble Code (DTC) memory again to make sure it is clear.
- Run the engine at idling speed.

WARNING: The electric radiator fan should not be running.






Display on VAS 5051:
- Select the diagnosis function "04 - Basic settings" from the menu -1-.







Display on VAS 5051:
1 - Enter display group
(figures up to 255)
- Using the keypad -2-, enter "056" to select Display group 056 and confirm entry with Q button.







Display on VAS 5051:
- Check whether the engine speed shown in display zone -1-(actual engine speed) is within the specified tolerance range.

Display Group 056:

NOTE:
- The value shown in display zone 1 is the actual engine speed.
- The value shown in display zone 2 (specified engine speed) is a theoretical value calculated by the engine control module.
- When the engine is idling the engine control module tries constantly to adjust the actual engine speed so that it matches the specified value.
- This means that the actual engine speed when idling should always be approximately the same as the specified engine speed.
- Display zones 3 and 4 provide additional information which is not relevant when checking the idling speed.







Display on VAS 5051:
If the specification is obtained:
- Press the <- button to exit from diagnosis function "04 - Basic settings".

If the specification is not attained:
- Check Diagnostic Trouble Code (DTC) memory again.
- If the Diagnostic Trouble Code (DTC) memory was erased the readiness code must be generated again. Readiness Code, Generating

Continued

If the idling speed is too high or too low and there are no faults recorded in the Diagnostic Trouble Code (DTC) memory, carry out the following tests (marked with dots):
- Test for unmetered air in the intake system.
- Test throttle valve control module.
- EVAP canister purge regulator valve constantly open, Testing
- Perform adaption of throttle valve control module.