Air/Fuel Mixture: Testing and Inspection

IDLE MIXTURE 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. Start the engine and increase the engine speed to 2,500 r/min for 2 minutes.
4. Check that the actual ignition timing is within the standard value.
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.

5. Set the CO, HC tester.
6. Check the CO contents and the HC contents at idle.
Standard value:

CO contents: 0.5 % or less
HC contents: 100 ppm or less
7. If the CO and HC contents do not remain inside the standard value, refer to Multiport Fuel Injection (MFI) [2.4L Engine] - Multiport Fuel Injection (MFI) Diagnosis - Symptom Chart Symptom Chart.
8. Remove the timing light and CO, HC tester.
9. Turn the ignition switch to the "LOCK" (OFF) position and disconnect the scan tool MB991958 from the data link connector.