Inspection Procedure 6: Ignition Timing Deviation




COMMENTS ON TROUBLE SYMPTOM




PROBABLE CAUSES




DIAGNOSIS PROCEDURE


STEP 1. M.U.T.-III diagnosis code


Q. Is diagnosis code stored?

Inspection chart for diagnosis code (Refer to ).
Go to Step 2.

STEP 2. Perform output wave pattern measurement at crank angle sensor and camshaft position sensor (Using an oscilloscope).


<Crank angle sensor>
  • Use the test harness (MB991709) to connect crank angle sensor connector, and measure at the pick-up harness.
  • Set the vehicle to the continuous idling mode.
  • Select lever position indicator: P
  • Voltage between terminal engine-ECU SGT line and body earth.
<Camshaft position sensor>
  • Use the test harness (MB991709) to connect camshaft position sensor connector, and measure at pick-up harness.
  • Set the vehicle to the continuous idling mode.
  • Select lever position indicator: P
  • Voltage between terminal engine-ECU CPI line and body earth.
OK: The timings on the output wave pattern at the both sensors should be the same as the specification in the inspection procedure using an oscilloscope (Refer to ).

Q. Is the check result normal?

Go to Step 3.
Go to Step 4.

STEP 3. Check the trouble symptom.


Q. Does the trouble symptom persist?

Replace the engine-ECU.
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).

STEP 4. Check crank angle sensor and camshaft position sensor for correct mounting condition.


Q. Is the check result normal?

Go to Step 5.
Repair.

STEP 5. Check timing mark on the timing chain.


Q. Is the check result normal?

Go to Step 6.
Align the timing marks on timing chain.

STEP 6. Check camshaft sensing portion.


Q. Is the check result normal?

Go to Step 7.
Replace the inlet camshaft.

STEP 7. Replace the crank angle sensor.



  • After replacing the crank angle sensor, re-check the trouble symptoms.

Q. Does the trouble symptom persist?

Go to Step 8.
Check end.

STEP 8. Replace the camshaft position sensor.


Q. Does the trouble symptom persist?

Go to Step 9.
Check end.

STEP 9. Replace the crankshaft sensing ring.



  • After replacing the crankshaft sensing ring, re-check the trouble symptoms.

Q. Does the trouble symptom persist?

Replace the engine-ECU.
Check end.