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
- VAG 1551 Scan Tool (ST) with VAG 1551/3 adapter cable
Test conditions
- No malfunctions stored in DTC memory.
- Engine Coolant Temperature (ECT) at least 85 °C (185 °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
Checking
- Connect VAG 1551 or VAG 1552 scan tool and press buttons -0- and -1- to insert "Engine Electronics" address word O1 (with engine running at idle). Connecting VAG 1551/1552 Scan Tool
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, 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
Continue with the test only when the operating conditions in display field 4 are satisfied.
- 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 -C- button.
- Press buttons -0-, -5- and -6- to input display group number 56, and press -Q- button to confirm input.
Indicated on display (1-4 = display fields)
System in Basic Setting 56 ->
1 2 3 4
- Compare display with specified values (display fields 1-4):
Display Group 56:
- Press -> button to advance program sequence.
- Press buttons -0- and -6- to select "End Output" function 06, and press -Q- button to confirm input.
- Road test vehicle, then repeat test.
- 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
Evaluation of 6-digit display:
- "1" = Adjustment conditions fulfilled
- "0" = Adjustment conditions not fulfilled
- If adjustment conditions have been fulfilled (indicated in display field 4), a series of 6 numerals ("1") will be displayed. If one of the digits in the 6-digit display is "0," the adjustment condition has not been fulfilled. Repair the cause of the unfulfilled condition, and repeat the test.
Evaluation of 4-digit display:
