Inspection Procedure 16: Ignition Timing Offset

COMMENT ON TROUBLE SYMPTOM

Failure is possibly caused by failed crank angle sensor, failed camshaft position sensor, improper installed timing chain or other faults.

PROBABLE CAUSES

Failed crank angle sensor
Failed camshaft position sensor
Improperly installed timing chain
Failed engine-ECU

DIAGNOSIS PROCEDURE

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

Q. Diagnosis code set?

	Inspection chart for diagnosis code (Refer to ).

	Go to Step 2 .

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

Crank Angle Sensor

Use special tool test harness (MB991709) to connect A-125 crank angle sensor intermediate connector, and measure at pick-up harness.
Engine: Idling
Transmission: Neutral
Voltage between terminal No. 2 and earth.

Camshaft Position Sensor

Use special tool test harness (MB991709) to connect A-109 camshaft position sensor connector, and measure at pick-up harness.
Engine: Idling
Transmission: Neutral
Voltage between terminal No. 2 and earth.

OK: Output waveform timings of both sensors are the same as the check procedure (Refer to ) using an oscilloscope.

Q. Is the check result normal?

Go to Step 3 .

Go to Step 4 .

STEP 3. Check the trouble symptoms.

Q. Does trouble symptom persist?

	Replace the engine-ECU then perform the variant coding (Refer to GROUP 00 - Precautions Before Service - How to Perform Variant Coding ).

	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 mounted conditions.

Q. Is the check result normal?

	Go to Step 5 .

	Repair.

STEP 5. Check timing marks of timing chain.

Q. Is the check result normal?

	Go to Step 6 .

	Align timing marks.

STEP 6. Check crank shaft sensing ring.

Q. Is the check result normal?

	Go to Step 7 .

	Replace crank shaft sensing ring.

STEP 7. Check camshaft position sensing ring.

Q. Is the check result normal?

	Go to Step 8 .

	Replace the intake camshaft.

STEP 8. Replace the crank angle sensor.

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

Q. Does trouble symptom persist?

	Go to Step 9 .

	Check end.

STEP 9. Replace the camshaft position sensor.

After replacing the camshaft position sensor, re-check the trouble symptoms.

Q. Does trouble symptom persist?

	Replace the engine-ECU then perform the variant coding (Refer to GROUP 00 - Precautions Before Service - How to Perform Variant Coding ).

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