Idle Speed: Adjustments

CHECKING IDLE SPEED

NOTES:
- Idle speed can NOT be manually adjusted.
- Idle speed is checked during "Basic Setting" function 04, refer to Diagnosis with Scan Tool, Address Word 01/Basic Setting/Display Group Diagnostic Charts Testing and Inspection. After selecting function 04, the learning values for idle speed and oxygen sensor control are relearned (idle speed and CO content are adjusted independently).
- CO content is controlled by oxygen sensor control for a specified value. Interference within oxygen sensor control will be captured via the On Board Diagnostic system and stored in DTC memory.

Test Conditions
- No leaks in exhaust system.
- Engine Coolant Temperature: 85°C (185°F) minimum.
- Throttle valve in closed throttle position. Adjust accelerator pedal cable if necessary.
- All electrical consumers switched OFF.
- A/C switched OFF.
- Pressure measuring devices NOT connected.
- Automatic transmission vehicles: selector lever in "P" or "N".
- Check DTC memory: There should be no malfunctions stored.If necessary;
- Repair malfunction.
- Erase DTC memory.
- stop engine (switch ignition OFF) and start again.
- Test drive and check DTC memory again to make sure no malfunctions are stored.

NOTE: Erasing DTC memory resets the readiness code (as well as with address word 01, "Basic Setting" function 04 and address word 33, mode 4).

WARNING: Do not take any measurements while the radiator coolant fan is running.

- Using VAG 1551 scan tool, select "Basic Setting" function 04, input display group number 003, and advance until the display shows "Basic Setting 3".

- Display will appear as shown: (1 to 4 = Display fields)

Basic Setting 3
1 2 3 4.

NOTE:
- Continue with test, if the engine coolant temperature exceeds 85°C (185°F) ~ display group 001, display field 1.
- Basic Setting" function 04 the EVAP canister purge regulator valve -N80- is closed.

- Briefly increase engine speed (RPM) and then let idle for another 2 minutes.
- Observe value in display field 1.

Specified Value: 650 to 750 RPM.

- Push ENTER button.
- Push buttons -0- and -6- to select "End Output" function 06.
- Press -Q- button to confirm input.

- If the specified value is not obtained:
- Check DTC memory again.

- If the idle speed is too high and there are no malfunctions stored in DTC memory:
- Check Closed Throttle Position (CTP) switch.
- Check for large intake air leak.
- Check Idle Air Control (IAC) valve.
- Check learning values for Idle Speed Control (ISC).

- If the idle speed is too low and there are no malfunctions stored in DTC memory:
- Check Closed Throttle Position (CTP) switch.
- Check Idle Air Control (IAC) valve.