Idle Speed, Checking

Idle Speed, Checking

NOTE:
- Idle speed, ignition timing and CO-content cannot be adjusted.
- Idle speed is maintained by the Throttle valve control module.
- CO-content is maintained and adjusted by Oxygen Sensor (O2S) control. Malfunctions in O2S control are recognized by On Board Diagnostic (OBD) and stored in DTC memory.

Required special tools and test equipment
- VAG1551 or VAG1552 Scan Tool (ST) with VAG1551/3 adapter cable

Test conditions
- Fuses for engine electronics OK
- No malfunctions stored in DTC memory.
- Engine Coolant Temperature (ECT) at least 80 °C (176 °F)
- All electrical consumers switched off (radiator coolant fan must not run during test)
- A/C switched off
- Exhaust system free of leaks
- Automatic transmission selector lever in "P" or "N" position
- Throttle valve in Closed Throttle Position (CTP).

Checking
- Connect VAG1551 or VAG1552 scan tool and press buttons -0- and -1- to insert "Engine Electronics" address word 01 (with engine running at idle). [1][2]Scan Tool Connecting and Initial Checks

Indicated on display

Rapid data transfer HELP
Select function XX

- Press buttons -0- and -4- to select "Basic Setting" function 04, and press -Q- button to confirm input.

Indicated on display

System in Basic Setting HELP
Input display group number XXX

- Press buttons -0-, -0- and -1- to input display group number 1(001), and press -Q- button to confirm input.

Indicated on display (1-4 = display fields)

System in Basic Setting 1 ->
1 2 3 4

NOTE:
After selecting function 04, the ECM initiates the following:
- EVAP canister purge regulator valve is closed
- A/C compressor is switched off

- Briefly raise engine speed (acceleration burst) and let engine run at idle for another 2 minutes.

- Compare display with specified values (display fields 1-4):

Display Group 1:

If displayed values are OK (as specified):
- Press -> button.
- Press buttons -0- and -6- to insert "End Output" address word 06, and press -Q- button to confirm input.
- Check readiness code. If Diagnostic Trouble Code (DTC) memory has been erased, or ECM was disconnected, generate new readiness code.
Readiness Code Reading
Readiness Code, Generating

NOTE: The increased idle speed for vehicles with frontwheel drive is achieved if there is voltage (from terminal 15er) supplied to terminal 10 of the Engine Control Module (ECM).

Evaluation of display group 1