Inspection Procedure 8: Unstable Idling (Rough Idling, Hunting), Improper Idling Speed (Too High or too Low), Engine Stalls during Idling (Die Out)

COMMENT ON TROUBLE SYMPTOM

Probable causes can be widely found in ignition system, air-fuel ratio control system, idle speed control system, fuel system, etc. A sudden engine stall is possibly caused by poor connector contact.

PROBABLE CAUSE

Failed ignition system

Failed fuel system

Failed air-fuel ratio control system

Failed idle speed control system

Failed intake/exhaust system

Failed emission gas cleaning system

Throttle valve body fouled

Timing belt out of place

Compression pressure improper

Failed engine-A/T-ECU

DIAGNOSIS PROCEDURE

STEP 1: Check battery condition.

Q: Has the battery terminal been disconnected?

YES: After warm-up engine, idle for about 10 minutes.
NO: Go to Step 2

STEP 2: MUT-II/III diagnosis code

Q: Diagnosis code set?

YES: Inspection chart for diagnosis code (Refer to

).
NO: Go to Step 3

STEP 3: MUT-II/III data list

Refer to Data List Reference Table .

Item 12: Air flow sensor

Item 13: Intake air temperature sensor

Item 14: Throttle position sensor (sub)

Item 21: Engine coolant temperature sensor

Item 77: Accelerator pedal position sensor (sub)

Item 78: Accelerator pedal position sensor (main)

Item 79: Throttle position sensor (main)

Item 95: Manifold absolute pressure sensor

Q: Are the check results normal?

YES: Go to Step 4

.
NO: 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 4: MUT-II/III data list

Refer to Data List Reference Table .

Item 25: Barometric pressure sensor

Q: Are the check results normal?

YES: Go to Step 5

.
NO: Replace engine-A/T-ECU.

STEP 5: MUT-II/III data list

Refer to Data List Reference Table .

Item 27: Power steering fluid pressure switch

Q: Is the check result normal?

YES: Go to Step 6

.
NO: Check power steering fluid pressure switch circuit (Refer to Code No. P0551

STEP 6: Check throttle body (throttle valve) contamination.

Q: Is the check result normal?

YES: Go to Step 7

.
NO: Clean throttle body (throttle valve portion) (Refer to

STEP 7: Check air intake from intake hose and inlet manifold.

Q: Is the check result normal?

YES: Go to Step 8

.
NO: Repair.

STEP 8: Check injector for operating sound.

Check injector for operating sound (Refer to ).

Q: Can operating sound be heard?

YES: Go to Step 9

.
NO:

Check the injector system of the defective cylinder.

(Refer to Code No. P0201: No. 1 Injector System ).

(Refer to Code No. P0202: No. 2 Injector System ).

(Refer to Code No. P0203: No. 3 Injector System ).

(Refer to Code No. P0204: No. 4 Injector System ).

STEP 9: Check timing marks of timing belt.

Q: Is the check result normal?

YES: Go to Step 10

.
NO: Align timing marks.

STEP 10. MUT-II/III data list

Refer to Data List Reference Table .

Item 11: Oxygen sensor

Item 39: Cylinder 2, 3 oxygen sensor (front) <Vehicles for Hong kong>

Item 59: Oxygen sensor (rear)

Item 69: Cylinder 2, 3 oxygen sensor (rear) <Vehicles for Hong kong>

Q: Is the check result normal?

YES: Go to Step 11

.
NO: 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 11. Perform voltage measurement at C-135 engine-A/T-ECU connector.

Measure engine-A/T-ECU terminal voltage.

Engine: Idling after warm-up

Transmission: P range

Radiator fan: Not operating

Voltage between terminal No. 45 and earth.

OK: Switching the headlamps to ON from OFF causes the voltage to increase.

Q: Is the check result normal?

YES: Go to Step 15

.
NO: Go to Step 12

STEP 12. Connector check: C-135 engine-A/T-ECU connector and B-30 alternator connector

Q: Is the check result normal?

YES: Go to Step 13

.
NO: Repair.

STEP 13. Check harness between C-135 (terminal No. 45) engine-A/T-ECU connector and B-30 (terminal No. 1) alternator connector.

NOTE: Before checking harness, check intermediate connector B-19, and repair if necessary.

Check output line for open/short circuit and damage.

Q: Is the check result normal?

YES: Go to Step 14

.
NO: Repair.

STEP 14. Replace alternator

After alternator is replaced, re-check for trouble symptom.

Q: Does trouble symptom persist?

YES: Replace engine-A/T-ECU.
NO: Check end.

STEP 15. Perform voltage measurement at C-136 engine-A/T-ECU connector.

Measure engine-A/T-ECU terminal voltage.

Engine: Idling

A/C switch: ON (A/C compressor ON)

Voltage between terminal No. 78 and earth.

OK:

1 V or less (with outside air temperature sensor ambient temperature at 18°C or higher and A/C set for maximum air flow at minimum temperature)

System voltage (with A/C set for minimum air flow at room temperature)

Q: Is the check result normal?

YES: Go to Step 16

.
NO: Check A/C load signal system (Refer to Inspection Procedure 29

STEP 16. Check ignition coil spark.

Q: Is the check result normal?

YES: Go to Step 17

.
NO: Check ignition circuit system (Refer to Inspection Procedure 31

STEP 17. Check injector for spray condition.

Check each injector for spray condition (Refer to ).

Q: Is the check result normal?

YES: Go to Step 18

.
NO: Replace injector.

STEP 18. Check compression pressure.

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

Q: Is the check result normal?

YES: Go to Step 19

.
NO: Repair.

STEP 19. Check purge control solenoid valve itself.

Check purge control solenoid valve itself (Refer to GROUP 17 - Emission Control System - Evaporative Emission Control System- Purge Control Solenoid Valve Check ).

Q: Is the check result normal?

YES: Go to Step 20

.
NO: Replace purge control solenoid valve.

STEP 20. Check EGR valve (stepper motor) itself.

Check EGR valve (stepper motor) itself [Refer to GROUP 17 - Emission Control System - Exhaust Gas Recirculation (EGR) System - EGR Valve (Stepper Motor) Check <4G69>].

Q: Is the check result normal?

YES: Go to Step 21

.
NO: Replace EGR valve (stepper motor).

STEP 21. MUT-II/III actuator test

Item 07: Fuel pump

OK: Operating sounds of fuel pump can be heard.

Q: Is the check result normal?

YES: Go to Step 22

.
NO: Check fuel pump system (Refer to inspection Procedure 25

STEP 22. Replace engine-A/T-ECU.

After engine-A/T-ECU is replaced, re-check for trouble symptom.

Q: Does trouble system persist?

YES: Check for foreign matters (water, kerosene, etc.) in fuel and replace if necessary.
NO: Check end.


Inspection Procedure 8: Unstable Idling (Rough Idling, Hunting), Improper Idling Speed (Too High or too Low), Engine Stalls during Idling (Die Out)

COMMENT ON TROUBLE SYMPTOM Probable causes can be widely found in ignition system, air-fuel ratio control system, idle speed control system, fuel system, etc. A sudden engine stall is possibly caused by poor connector contact.
PROBABLE CAUSE Failed ignition system Failed fuel system Failed air-fuel ratio control system Failed idle speed control system Failed intake/exhaust system Failed emission gas cleaning system Throttle valve body fouled Timing belt out of place Compression pressure improper Failed engine-A/T-ECU
	DIAGNOSIS PROCEDURE

	STEP 1: Check battery condition. Q: Has the battery terminal been disconnected? YES: After warm-up engine, idle for about 10 minutes. NO: Go to Step 2 .
	STEP 2: MUT-II/III diagnosis code Q: Diagnosis code set? YES: Inspection chart for diagnosis code (Refer to ). NO: Go to Step 3 .
	STEP 3: MUT-II/III data list Refer to Data List Reference Table . Item 12: Air flow sensor Item 13: Intake air temperature sensor Item 14: Throttle position sensor (sub) Item 21: Engine coolant temperature sensor Item 77: Accelerator pedal position sensor (sub) Item 78: Accelerator pedal position sensor (main) Item 79: Throttle position sensor (main) Item 95: Manifold absolute pressure sensor Q: Are the check results normal? YES: Go to Step 4 . NO: 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 4: MUT-II/III data list Refer to Data List Reference Table . Item 25: Barometric pressure sensor Q: Are the check results normal? YES: Go to Step 5 . NO: Replace engine-A/T-ECU.
	STEP 5: MUT-II/III data list Refer to Data List Reference Table . Item 27: Power steering fluid pressure switch Q: Is the check result normal? YES: Go to Step 6 . NO: Check power steering fluid pressure switch circuit (Refer to Code No. P0551 ).
	STEP 6: Check throttle body (throttle valve) contamination. Q: Is the check result normal? YES: Go to Step 7 . NO: Clean throttle body (throttle valve portion) (Refer to ).
	STEP 7: Check air intake from intake hose and inlet manifold. Q: Is the check result normal? YES: Go to Step 8 . NO: Repair.
	STEP 8: Check injector for operating sound. Check injector for operating sound (Refer to ). Q: Can operating sound be heard? YES: Go to Step 9 . NO: Check the injector system of the defective cylinder. (Refer to Code No. P0201: No. 1 Injector System ). (Refer to Code No. P0202: No. 2 Injector System ). (Refer to Code No. P0203: No. 3 Injector System ). (Refer to Code No. P0204: No. 4 Injector System ).
	STEP 9: Check timing marks of timing belt. Q: Is the check result normal? YES: Go to Step 10 . NO: Align timing marks.
	STEP 10. MUT-II/III data list Refer to Data List Reference Table . Item 11: Oxygen sensor Item 39: Cylinder 2, 3 oxygen sensor (front) <Vehicles for Hong kong> Item 59: Oxygen sensor (rear) Item 69: Cylinder 2, 3 oxygen sensor (rear) <Vehicles for Hong kong> Q: Is the check result normal? YES: Go to Step 11 . NO: 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 11. Perform voltage measurement at C-135 engine-A/T-ECU connector.
	Measure engine-A/T-ECU terminal voltage. Engine: Idling after warm-up Transmission: P range Radiator fan: Not operating Voltage between terminal No. 45 and earth. OK: Switching the headlamps to ON from OFF causes the voltage to increase. Q: Is the check result normal? YES: Go to Step 15 . NO: Go to Step 12 .
	STEP 12. Connector check: C-135 engine-A/T-ECU connector and B-30 alternator connector
	Q: Is the check result normal? YES: Go to Step 13 . NO: Repair.
	STEP 13. Check harness between C-135 (terminal No. 45) engine-A/T-ECU connector and B-30 (terminal No. 1) alternator connector.
	NOTE: Before checking harness, check intermediate connector B-19, and repair if necessary. Check output line for open/short circuit and damage. Q: Is the check result normal? YES: Go to Step 14 . NO: Repair.
	STEP 14. Replace alternator After alternator is replaced, re-check for trouble symptom. Q: Does trouble symptom persist? YES: Replace engine-A/T-ECU. NO: Check end.
	STEP 15. Perform voltage measurement at C-136 engine-A/T-ECU connector.
	Measure engine-A/T-ECU terminal voltage. Engine: Idling A/C switch: ON (A/C compressor ON) Voltage between terminal No. 78 and earth. OK: 1 V or less (with outside air temperature sensor ambient temperature at 18°C or higher and A/C set for maximum air flow at minimum temperature) System voltage (with A/C set for minimum air flow at room temperature) Q: Is the check result normal? YES: Go to Step 16 . NO: Check A/C load signal system (Refer to Inspection Procedure 29 ).
	STEP 16. Check ignition coil spark. Q: Is the check result normal? YES: Go to Step 17 . NO: Check ignition circuit system (Refer to Inspection Procedure 31 ).
	STEP 17. Check injector for spray condition. Check each injector for spray condition (Refer to ). Q: Is the check result normal? YES: Go to Step 18 . NO: Replace injector.
	STEP 18. Check compression pressure. Check compression pressure (Refer to GROUP 11E - On-vehicle Service - Compression Pressure Check ). Q: Is the check result normal? YES: Go to Step 19 . NO: Repair.
	STEP 19. Check purge control solenoid valve itself. Check purge control solenoid valve itself (Refer to GROUP 17 - Emission Control System - Evaporative Emission Control System- Purge Control Solenoid Valve Check ). Q: Is the check result normal? YES: Go to Step 20 . NO: Replace purge control solenoid valve.
	STEP 20. Check EGR valve (stepper motor) itself. Check EGR valve (stepper motor) itself [Refer to GROUP 17 - Emission Control System - Exhaust Gas Recirculation (EGR) System - EGR Valve (Stepper Motor) Check <4G69>]. Q: Is the check result normal? YES: Go to Step 21 . NO: Replace EGR valve (stepper motor).
	STEP 21. MUT-II/III actuator test Item 07: Fuel pump OK: Operating sounds of fuel pump can be heard. Q: Is the check result normal? YES: Go to Step 22 . NO: Check fuel pump system (Refer to inspection Procedure 25 ).
	STEP 22. Replace engine-A/T-ECU. After engine-A/T-ECU is replaced, re-check for trouble symptom. Q: Does trouble system persist? YES: Check for foreign matters (water, kerosene, etc.) in fuel and replace if necessary. NO: Check end.