Idle Speed and CO Checking
Idle Speed and CO, Checking
Idle Speed, Checking
NOTE:
- Idle speed, ignition timing and CO content NOT adjustable.
- Idle speed is regulated to specification by the Throttle Position sensor in conjunction with the DIS function.
- CO content is regulated by Oxygen sensor control. Malfunctions in Oxygen control are detected via On Board Diagnostic II and stored in DTC memory.
Special tools, workshop equipment, testers, measuring instruments and auxiliary items required
- VAG 1551/1552 Scan Tool with VAG 1551/3 Adaptor cable
Requirements
- Exhaust system between cyl. head and catalyst leak-free.
- ALL electrical consumers must be switched OFF
- A/C switched OFF, if installed
- Automatic transmission Range selector lever in "P" or "N"
- Throttle cable adjustment OK. Checking:
- Cruise control system functioning correctly, if installed.
- Engine Coolant Temperature 85 °C minimum.
Test sequence
- Connect VAG 1551/1552 Scan Tool. [1][2][3][4]Reading and Clearing Diagnostic Trouble Codes
- Start engine and let idle
- Press 0 and 1 buttons to select "Engine Electronics" address word 01.
- Check DTC memory, if necessary, repair malfunction and then erase DTC memory.
- Continue idling engine with Scan Tool connected
Indicated on display (example only)
06A906018AB Motronic M5.9.2 HS V06 ->
Coding 00000 WSC 00000
- Press -> button.
Indicated on display
Rapid data transfer HELP
Select function XX
- Press 0 and 4 buttons to select Function 04: "Basic setting"
- Press Q button to enter input.
Indicated on display
Basic setting
Input Display group number XXX
- Press 0, 0 and 1 buttons to select "Display group 1"
- Press Q button to enter input.
Indicated on display (1 to 4 = Display fields)
System in Basic setting 1 ->
1 2 3 4
NOTE:
- When system is in "Basic setting", the EVAP canister purge regulator valve 1 N80 is closed and the A/C compressor is switched OFF.
- Do not continue with check until Engine Coolant Temperature exceeds 85 °C (Display field 2).
- Briefly increase engine speed then let idle for 2 minutes.
- Check specifications (Display fields 1 to 4)
If specifications obtained
- Press C button.
- Press 0, 5 and 6 buttons for "Display group 56"
- Press Q button to enter input.
Indicated on display (1 to 4 = Display fields)
System in Basic setting 56 ->
1 2 3 4
Significance of values in 4 digit number block in Display field 4, Display group 56
NOTE: The increased engine speed at idle is obtained via terminal 10 of the ECM which receives a Battery + signal from terminal 15.
- Press -> button.
Indicated on display
Rapid data transfer HELP
Select function XX
- Press 0 and 6 buttons to select "End output" function 06.
- Press Q button to enter input.
- Take road test and repeat check.
Observe appropriate safety precautions during road test.
- Display the Readiness code. Monitors, Trips, Drive Cycles and Readiness Codes
- If DTC memory was erased or if the ECM was disconnected from Battery + , set the Readiness code. Monitors, Trips, Drive Cycles and Readiness Codes