Basic Idle Speed Adjustment

Required Special Tool:
MB991502: Scan Tool

NOTE: The standard idling speed has been adjusted with the speed adjusting screw (SAS), by the manufacturer and there should be no need for readjustment.

NOTE: If the adjustment has been changed by mistake, the idle speed may become too high or the idle speed may drop too low when loads A/C, defogger, etc. are placed on the engine. If this occurs, adjust by The following procedure.

NOTE: The adjustment, if made, should be made after first confirming that the spark plugs, the injectors, the idle air control motor, compression, etc., are all normal.

1. The vehicle should be prepared as follows before the inspection and adjustment.
- Engine coolant temperature: 80 - 95°C (176 - 203°F)
- Lights and accessories: OFF
- Transmission: Neutral




NOTE: When scan tool, MB991502, is connected, the diagnostic test mode control terminal should be grounded.

2. Connect scan tool, MB991502, to the data link connector (16-pin).
3. Start the engine and run at idle.

NOTE: Use the scan tool to hold the IAC motor at the basic step to adjust the basic idle speed.

4. Select the item number 30 of the scan tool Actuator test.

NOTE: The engine speed may be 20 to 100 r/min lower than indicated above for a new vehicle [driven approximately 500 km (300 mile) or less], but no adjustment is necessary.

NOTE: If the engine stalls or the engine speed is low even though the vehicle has been driven approximately 500 km (300 mile) or more, it is probable that deposits are adhered to the throttle valve, so clean it.

5. Check the idle speed.

Standard value: 75 ± 50 r/min




6. If not within the standard value range, turn the speed adjusting screw (SAS) to make the necessary adjustment.

NOTE: If the idling speed is higher than the standard value range even when the SAS is fully closed, check whether or not there is any indication that the fixed SAS has been moved. If there is an indication that it has been moved, adjust the fixed SAS.

7. Press the scan tool clear key and release the IAC motor Actuator test mode.

NOTE: Unless the IAC motor is released, the Actuator test mode will continue 27 minutes.

8. Turn the ignition switch "OFF".
9. Disconnect scan tool, MB991502.
10. Start the engine again and let it idle for about 10 minutes. Check that the idling condition is normal.