Idle Speed: Testing and Inspection

CURB IDLE SPEED CHECK

^ Required Special Tool:
- MB991958: Scan Tool (MUT-III Sub Assembly)
^ MB991824: V.C.I.
^ MB991827: MUT-III USB Cable
^ MB991911: MUT-III Main Harness B

1. Before checks, set the vehicle in the following condition.
^ Engine coolant temperature: 80 - 95°C (176 - 203°F)
^ Lights and all accessories: OFF
^ Transaxle: Neutral (P range on vehicles with A/T)

NOTE: Vehicles for Canada, the headlight, taillight, etc. remain lit even when the lighting switch is in "OFF" position but this is no problem for checks.





CAUTION: To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.

2. Connect scan tool MB991958 to the data link connector.
3. Check the basic ignition timing.
Standard value: 5° BTDC ± 3°
4. Start the engine.
5. Run the engine at idle for 2 minutes.
6. Check the idle speed. Select item number 22 and take a reading of the idle speed.
Curb idle speed: 750 ± 100 r/min

NOTE: The idle speed is controlled automatically by the idle air control system.

7. If the idle speed is outside the standard value, refer to Multiport Fuel Injection (MFI) <2.4L Engine> - Multiport Fuel Injection (MFI) Diagnosis - Symptom Chart.