Inspection Procedure 7: Improper Idling

PROBABLE CAUSES

Improper fuel used
Fuel contaminated with foreign matter
Injector leaking or clogged
Failed injector
Fuel injection learning failure
Fuel filter clogged
Fuel line leaking or clogged
Failed fuel pressure limiter valve
Failed fuel pressure sensor
Failed supply pump (suction control valve)
Failed supply pump correction learning
Failed EGR system operation
Open/short circuit or harness damage in alternator FR terminal circuit
Failed alternator
Failed valve clearance adjustment
Failed engine-ECU
Compression pressure low

DIAGNOSIS PROCEDURE

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

Q. Is the diagnosis code set?

	Inspection chart for diagnosis code (Refer to ).

	Go to Step 2.

STEP 2. M.U.T.-III data list.

Refer to Data List Reference Table .

Item 5: Barometric pressure sensor
Item 6: Manifold absolute pressure sensor
Item 7: Engine coolant temperature sensor
Item 8: EGR gas temperature sensor
Item 9: Accelerator pedal position sensor (main)
Item 10: Accelerator pedal position sensor (sub)
Item 21: Fuel temperature sensor
Item 43: Intake air temperature sensor
Item 45: Throttle position sensor

Q. Are the check results normal?

	Go to Step 3.

	Perform the diagnosis code classified check procedure for the sensor that has shown an abnormal data value (Refer to Inspection Chart for Diagnosis Code ).

STEP 3. Check injector identification code.

Check injector identification code (Refer to GROUP 00 - Precautions before Service - Injector Identification Code Registration Procedure <4N1> ).

Q. Is the check result normal?

	Go to Step 4.

	Register the injector ID.

STEP 4. M.U.T.-III data list.

Refer to Data List Reference Table .

Item 16: EGR valve position sensor
Item 17: EGR valve target position

Q. Are the check results normal?

	Go to Step 5.

	Perform the diagnosis code classified check procedure for the sensor that has shown an abnormal data value (Refer to Inspection Chart for Diagnosis Code ).

STEP 5. Check the using fuel.

Check for foreign matters (water, petrol fuel, etc.) in fuel

Q. Is the specified fuel being used?

	Go to Step 6.

	Replace the fuel.

STEP 6. Check fuel supply line.

Check for fuel leakage and clogging.
Check fuel filter for clogging.

Q. Is the check result normal?

	Go to Step 7.

	Repair.

STEP 7. M.U.T.-III actuator test.

Refer to Actuator Test Reference Table .

Item 19: Suction control valve

Q. Is the check result normal?

	Go to Step 8.

	Check suction control valve system (Refer to Code No. P0003 , Refer to Code No. P0004 ).

STEP 8. M.U.T.-III data list.

Refer to Data List Reference Table .

Item 63: Rail pressure sensor
Item 64: Rail pressure target

Q. Are the check results normal?

	Go to Step 11.

	Go to Step 9.

STEP 9. Replace the fuel pressure sensor.

After replacing the common-rail assembly, re-check the trouble symptoms.

Q. Does the trouble symptom persist?

	Go to Step 10.

	Check end.

STEP 10. Check the trouble symptoms.

Q. Does the trouble symptom persist?

	Replace the supply pump assembly.

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

STEP 11. Perform voltage measurement at engine-ECU connector.

Disconnect engine-ECU connector, and connect special tool power plant ECU check harness (MB992291) to measure at connector for inspection.
Engine: Idle operation after warm-up
Transmission: Neutral
Radiator fan: Not operated
Voltage between terminal ALTF and body earth.

OK: The voltage increases when the headlamp switch and the rear window defogger switch are turned ON from OFF.

Q. Is the check result normal?

	Go to Step 14.

	Go to Step 12.

STEP 12. Check harness between engine-ECU connector terminal ALTF and alternator connector terminal.

Check output line for open/short circuit and damage.

Q. Is the check result normal?

	Go to Step 13.

	Repair or replace the connector, or repair the damaged harness wire.

STEP 13. Check the trouble symptom.

Q. Does the trouble symptom persist?

	Replace the alternator.

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

STEP 14. Check compression pressure.

Check compression pressure (Refer to GROUP 11E - On-vehicle Service - Compression Pressure Check ).

Q. Is the check result normal?

	Go to Step 15.

	Repair.

STEP 15. Check valve clearance.

Check valve clearance (Refer to GROUP 11E - On-vehicle Service - Valve Clearance Check and Adjustment ).

Q. Is the check result normal?

	Go to Step 16.

	Adjust the valve clearance.

STEP 16. M.U.T.-III actuator test.

Refer to Actuator Test Reference Table .

Item 15: Injector No. 1
Item 16: Injector No. 2
Item 17: Injector No. 3
Item 18: Injector No. 4

Q. Are the check results normal?

	Go to Step 17.

	Check the injector system of the defective cylinder. (Refer to Code No. P0201: No. 1 Injector Circuit Malfunction ) (Refer to Code No. P0202: No. 2 Injector Circuit Malfunction ) (Refer to Code No. P0203: No. 3 Injector Circuit Malfunction ) (Refer to Code No. P0204: No. 4 Injector Circuit Malfunction )

STEP 17. Check injector itself.

Check injector itself (Refer to ).

Q. Is the check result normal?

	Go to Step 18.

	Replace the injector at the failed cylinder.

STEP 18. Check the trouble symptoms.

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 ).