Air/Fuel Mixture: Testing and Inspection

NOTES:
- The engine idle speed, ignition timing and CO content are NOT adjustable.
- Engine idle speed is maintained at a specified value by the Idle Air Control (IAC) valve and the digital idle speed stabilization function of the ECM.
- CO content is maintained at a specified value by Oxygen Sensor (O2S) control. Malfunctions in O2S control are detected by the On Board Diagnostic (OBD) system and stored in Diagnostic Trouble Code (DTC) memory
- Checking CO content before the Three Way Catalytic Converters (TWC) is not possible.
- When the ECM or the battery is disconnected, all learned values will be erased.
- Engine basic settings => Refer to "Diagnosis With Scan Tool, Address Word 01" at "On-Board Diagnostics II". Testing and Inspection

REQUIREMENTS:
- Engine coolant temperature at least 85°C (185°F).
- All electrical consumers switched off (radiator coolant fan must not be running while checking idle speed).
- A/C switched OFF.
- Automatic transmission selector lever in P or N position.

PROCEDURE:
- Connect VAG 1551 (VAG 1552) Scan Tool (ST) and press buttons -0- and -1- to insert "Engine Electronics" address word 01 (engine running at idle). Refer to "How to Display and Read Diagnostic Trouble Codes" at "On-Board Diagnostics II". Testing and Inspection

CAUTION: The radiator coolant fan must not run.
Indicated on display:

Rapid data transfer HELP
Select function XX

- Press buttons -0- and -8- to select "Read Measuring Value Block" function 08, and press -Q- button to confirm input.
Indicated on display:

Read Measuring Value Block
Input display group number XXX

- Press buttons -0-, -0- and -5- to input display group number 5, and press -Q- button to confirm input.
Indicated on display:

Read Measuring Value Block 5 ->
1 2 3 4




- Check specified engine idle speed values (display fields 1-2).
- Press -> button to advance program sequence.
- Press buttons -0- and -6- to select "End Output" function 06, and press -Q- button to confirm input.