Inspection Procedure 12: Hesitation, Sag, Poor Acceleration, Stumble, Surge

COMMENT ON TROUBLE SYMPTOM

Failure is possibly caused by failed ignition system, improper air-fuel ratio, throttle valve control system, improper compression pressure and so on.

PROBABLE CAUSE

Failed air-fuel ratio control system
Failed ignition system
Failed fuel system
Failed intake and exhaust system
Failed emission control system
Failed throttle valve control system
Improper compression pressure
Failed engine-ECU <M/T>
Failed engine-A/T-ECU <A/T>

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. Check injector for operating sound.

Check injector for operating sound (Refer to ).

Q. Can operating sound be heard?

	Go to Step 3 .

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

STEP 3. M.U.T.-III data list

Refer to Data List Reference Table .

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)

Q. Are the check results normal?

	Go to Step 4 .

	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: M.U.T.-III data list

Refer to Data List Reference Table .

Item 25: Barometric pressure sensor

Q. Are the check results normal?

	Go to Step 5 .

	Replace engine-ECU <M/T> or engine-A/T-ECU <A/T>.

STEP 5. 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?

	Go to Step 6 .

	Replace purge control solenoid valve.

STEP 6. 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 ].

Q. Is the check result normal?

	Go to Step 7 .

	Replace EGR valve (stepper motor).

STEP 7. M.U.T.-III data list

Refer to Data List Reference Table .

Item 11: Cylinder 1, 4 oxygen sensor
Item 39: Cylinder 2, 3 oxygen sensor

Q. Are the check results normal?

	Go to Step 8 .

	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 8. Check spark plug.

Q. Is the check result normal?

	Go to Step 9 .

	Replace spark plug.

STEP 9. Check ignition coil spark.

Q. Is the check result normal?

	Go to Step 10 .

	Check ignition circuit system (Refer to Inspection Procedure 26 ).

STEP 10. Check throttle body (throttle valve portion) for contamination.

Q. Is the check result normal?

	Go to Step 11 .

	Clean throttle body (throttle valve portion) (Refer to ).

STEP 11. Fuel pressure measurement.

Fuel pressure measurement (Refer to Fuel Pressure Test ).

Q. Is the check result normal?

	Go to Step 12 .

	Repair.

STEP 12. Check compression pressure.

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

Q. Is the check result normal?

	Replace engine-ECU <M/T> or engine-A/T-ECU <A/T>.

	Repair.