Idle Speed: Testing and Inspection

Idle Speed (RPM), Checking

Special tools and equipment







- VAS5051 with VAG5051/1
or
- VAG1551 with VAG1551/3A

Test requirements:
- Exhaust system free of leaks.
- Coolant Temperature at least 80 °C.
- Electrical consumers switched off (radiator fan must NOT run during test).
- A/C switched off.
- No pressure gauge connected.
- Vehicles with automatic transmission Selector lever in P or N.


NOTE:
- Idle speed cannot be adjusted.
- Idle speed is checked during basic setting of the engine.
- During basic setting, the Evaporative Emission (EVAP) canister purge regulator valve (EVAP valve -N80-) is closed and the A/C compressor is switched off.


Test sequence
- Check DTC memory. There must not be any DTCs stored, repair malfunctions if necessary, erase DTC memory, switch engine off and start again, road test vehicle and check DTC memory again as a control measure.
- Let engine continue to run at idle.


WARNING!
The electric fan for the radiator must not be running.


When indicated on display


Rapid data transfer HELP
Select function XX


- Press buttons -0- and -4- to select "Initiate basic setting" and press -Q- button to confirm input.

When indicated on display


Basic Setting Q
Enter display group number XXX


- Press buttons -0-, -5- and -6- to select "display group number 056" and press -Q- button to confirm input.

When indicated on display


System in basic setting 56 ->
1 2 3 4


- Check whether the engine speed in display field 1 (actual engine speed) is within tolerated range.

Display Group 056:

If specified value is obtained:
- Press -> button.

Indicated on display (function selection):


Rapid data transfer HELP
Select function XX


If specified value is not obtained:
- Check DTC memory again.
- If DTC memory was erased, readiness code must be re-generated. Refer to "Monitors, Trips and/or Drive Cycle (Readiness Codes)/Generating Readiness Code" Testing and Inspection

If idle speed is too high or low and there are no DTCs in DTC memory, the following tests (marked with dots) must be performed:
- Check for false air in intake air system. Refer to "Intake System, Checking For Leaks (Unmetered Air)" Testing and Inspection
- Check throttle valve control module Testing and Inspection
- Evaporative Emission (EVAP) canister purge regulator valve always open, Testing and Inspection
- Perform adaptation of throttle valve control module
.

Significance of 5 digit indication of display group 056