Idle Speed: Testing and Inspection

Idle speed, checking

Test conditions
- No leaks in exhaust system
- Coolant temperature at least 85 ° C (185 ° F)
- Electrical consumers switched off (radiator fan must not run during the check)
- A/C switched off
- VAG 1318 Pressure gauge not connected
- Selector lever in position P or N (vehicles with automatic transmission)

Idle speed, checking


NOTE:
- The idle speed cannot be adjusted.
- The idle speed is tested during the basic setting of the engine.
- During the basic setting of the engine the A/C compressor is automatically switched off and the EVAP canister purge regulator valve is closed.


- Check DTC memory. The DTC memory must be clear. If necessary, correct any malfunctions and erase DTC memory. Switch off engine, then start up again. Take vehicle for a test drive and check DTC memory again to make sure it is clear.
- Run engine at idle speed.
- Switch A/C off.
- Switch rear window heater off.
- Place selector lever in P or N position (automatic transmission).


CAUTION!
The electric radiator fan should not be running.


Indicated on display

Rapid data transfer HELP
Select function XX

- Press buttons -0- and -4- to select function "Basic Setting" and confirm entry with -Q- key.

Indicated on display

Basic setting
Input display group number XXX

- Press buttons -0- -5- and -6- to select "display group number 056" and confirm entry with -Q- button.

Indicated on display: (1 to 4 display fields)

System in Basic Setting 56 ->
1 2 3 4

- Check whether the engine speed shown in display zone 1 (actual engine speed) is within the specified range (670 - 730RPM).







- Press -> button
- Press buttons -0- and -6- to select function "End Output" and confirm entry with -Q- button.
- If readout does not match Specified value, check DTC memory again.
- If DTC memory was erased, generate readiness code, Refer to "Monitors, Trips and/or Drive Cycle (Readiness Code)/Generating Readiness Code" Testing and Inspection

If the idle speed is too high or too low, or if the engine does not idle smoothly, and there are no malfunctions stored in the DTC memory, carry out the following tests (marked with dots):

- Check oxygen sensor learned (adaptation) values and oxygen sensor control, Refer to "Oxygen Sensor (O2S) Before Catalyst/Sensor and Sensor Control Check"
- Check for un-metered air (air leaks) in the intake system.
- EVAP canister purge regulator valve constantly open, check, Testing and Inspection
- Adaptation of Throttle Valve Control Module, Refer to Adaptation of Throttle Valve Control Module, Performing" Testing and Inspection

Relevance of figures in 5-digit readout in Display Group 056