Ignition Timing: Testing and Inspection
IGNITION TIMING CHECKRequired 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.
CAUTION: To prevent damage to scan tool MB9911958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB9911958.
2. 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 power supply line (terminal No. 1) of the ignition coil No. 1.
4. Start the engine and run it at idle.
5. Check that the idle speed is approximately 700 r/min.
6. Select the scan tool MB991958 actuator test "item number 11".
7. Check that basic ignition timing is within the standard value.
Standard value: 5° BTDC ± 3°
8. If the basic ignition timing is not within the standard value, check the following items:
^ Diagnostic output
^ Timing belt cover and crankshaft position sensor installation conditions
^ Crankshaft sensing blade condition
CAUTION: If the actuator test is not canceled, the forced drive will continue for 27 minutes. Driving in this state could lead to engine failure.
9. Cancel the setting mode of the scan tool MB991958.
10. 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.
11. Remove the timing light.
12. Turn the ignition switch to the "LOCK" (OFF) position and disconnect the scan tool MB991958 from the data link connector.