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 TC-SST)

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.

Connect scan tool MB991958 to the data link connector.





3. Set the timing light to the power supply line (terminal No. 4) of the ignition coil No.
1.
4. Start the engine and let it run at idle.
5. Check that the actual ignition timing is at the standard value.
Standard value: Approximately 10° BTDC
NOTE:
Ignition timing fluctuates about ±7° , even under normal operating condition.

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

NOTE:
Wait till approximately 1 minute passes after the engine started, and check the ignition timing when the engine stabilized.

6. Run the engine and increase the engine speed to 2,000 - 3,000 r/min for 2 minutes.
7. Set the CO, HC tester.
8. Check the CO contents and the HC contents at idle.
Standard value:

CO contents: 0.5% or less
HC contents: 100 ppm or less
9. If there is a deviation from the standard value, inspect the MFI system Symptom Chart)
10. Remove the CO.HC tester and timing light.

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.

11. Disconnect scan tool MB991958 from the data link connector.