Inspection Procedure 14: Ignition Timing Deviation






COMMENTS ON TROUBLE SYMPTOM



  • The failure could possibly be caused by the failed crank angle sensor, faulty inlet camshaft position sensor, improper assembled timing chain and so on.

PROBABLE CAUSES



  • Failed crank angle sensor
  • Failed inlet camshaft position sensor
  • Timing chain in out of place
  • Failed engine-ECU

DIAGNOSIS PROCEDURE

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

Q. Is diagnosis code set?
Inspection chart for diagnosis code (Refer to ).
Go to Step 2.

STEP 2. Perform output wave pattern measurement at crank angle sensor and inlet camshaft position sensor (Using an oscilloscope).
<Crank angle sensor>
  • Use the test harness (MB991709) to connect B-15 crank angle sensor connector, and measure at the pick-up harness.
  • Engine: Idling
  • Transmission: P range
  • Voltage between terminal No. 3 and earth.
<Inlet camshaft position sensor>
  • Use the test harness (MB991709) to connect B-19 inlet camshaft position sensor connector, and measure at pick-up harness.
  • Engine: Idling
  • Transmission: P range
  • Voltage between terminal No. 3 and 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 inlet 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 inlet 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 inlet 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.