Idle Speed (RPM), Checking

Idling Speed, Checking

Special tools and equipment







- VAS 5051 with VAS 5051/1

Test requirements

- No leaks in exhaust system.
- Engine coolant temperature at least 80 degree C.
- Electrical accessories switched off (coolant fan must not run during the test).
- Air conditioning switched off.
- Pressure gauge not connected.
- Vehicles with automatic transmission: Selector lever in position P or N.

NOTE:
- The idling speed is tested during the basic setting of the engine.
- During basic setting, the solenoid valve for the evaporative emission (EVAP) canister purge regulator valve -N80- is closed and the air conditioner compressor is switched off.
- To eliminate vibration noises in case of a customer complaint, the idling speed can be adapted. Adaptation (Function 10)

Test sequence
- Connect testing and information system VAS 5051 and select vehicle system "01 - Engine electronics" in selection. Engine must be running at idling speed. Connecting VAS 5051 Scan Tool
- Check Diagnostic Trouble Code (DTC) memory. There must not be any DTCs stored. If necessary, correct any DTCs and erase DTC memory. After erasing DTC memory readiness code must be regenerated. Readiness Code, Generating
- Leave engine idling.

CAUTION: The coolant fan should not be running.

Display on VAS 5051:







- Under -1- select diagnostic function "04 - Basic setting".

Display on VAS 5051:







1 - Enter display group max. input value = 255.
- Enter "056" for "display group number 056" in zone -2- and confirm entry by pressing -Q- button.

Display on VAS 5051:







- Activate basic setting by pressing -A- button.
- Check whether engine speed in display zone -1- (actual speed) is within permitted tolerance range.

All models

Display Group 056:

- Exit function "04 - Basic setting" by pressing <- button.

If specified value is not obtained:

- Check Diagnostic Trouble Code (DTC) memory again.
- If DTC memory was erased, readiness code must be re-generated. Readiness Code, Generating

If the idling speed is too high or too low and there are no DTCs recorded in the DTC memory, perform the following tests marked with a dot:

- Check intake air system for unmetered air. [1][2]Checking Intake Air System For Leaks (Unmetered or False Air)
- Check throttle valve control module. Throttle Valve Control Module -J338-, Checking
- Check whether solenoid valve for Evaporative Emission (EVAP) canister purge regulator valve is continuously open. Testing and Inspection
- Perform adaptation of throttle valve control module.

Significance of 5-digit readout of display group 056