Idle Speed: Testing and Inspection

CURB IDLE SPEED CHECK

Required Special Tool:

MB991958: Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: M.U.T.-III USB Cable
- MB991910: M.U.T.-III Main Harness A

1. Before inspection, 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:
On 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.





2.
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.

Turn the ignition switch to the "LOCK" (OFF) position and connect the scan tool MB991958 to the data link connector.





3. Set a timing light to the terminal No. 1 power supply line (black-orange) of the ignition coil No. 1.
NOTE:
The power supply line is looped and also longer than the other one.

4. Start the engine.
5. Run the engine at idle for 2 minutes.
6. Check the actual ignition timing.
Standard value: Approximately 10° BTDC
NOTE:
ignition timing fluctuates ±7°, even under normal operating condition.

NOTE:
It is automatically further advanced by about 5° from 10° Before Top Dead Center at higher altitudes.

7. Check the idle speed. Select item number 2 and take a reading of the idle speed.
Curb idle speed: 700± 100 r/min
NOTE:
The idle speed is controlled automatically by the idle air control system.

8. 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 Symptom Chart.
9. Remove the timing light.
10. Turn the ignition switch to the "LOCK" (OFF) position and disconnect the scan tool MB991958 from the data link connector.