Inspection Procedure 11: Hesitation, Sag, Poor Acceleration, Stumble, Surge

COMMENTS ON TROUBLE SYMPTOM

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

PROBABLE CAUSES

Failed air-fuel ratio control system
Failed ignition system
Failed fuel system
Failed intake and exhaust air system
Failed exhaust gas cleaning system
Failed electronic control throttle valve system
Contamination around the throttle valve
Improper compression pressure
Failed engine-ECU <M/T> or engine-A/T-ECU <A/T>

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. Check injector for operating sound.

Check injector for operating sound (Refer to ).

Q. Is operating sound audible?

	Go to Step 3 .

	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 ). (Refer to Code No. P0205: No. 5 Injector System ). (Refer to Code No. P0206: No. 6 Injector System ).

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

Refer to Data List Reference Table .

Item 05: Intake air temperature sensor
Item 06: Engine coolant temperature sensor
Item 11: Accelerator pedal position sensor (main)
Item 12: Accelerator pedal position sensor (sub)
Item 13: Throttle position sensor (main)
Item 15: Throttle position sensor (sub)

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. Check purge control solenoid valve itself.

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

Q. Is the check result normal?

	Go to Step 5 .

	Replace the purge control solenoid valve.

STEP 5. Check exhaust gas recirculation valve itself.

Check exhaust gas recirculation valve itself (Refer to GROUP 17 - Emission Control - Exhaust Gas Recirculation Valve - Exhaust Gas Recirculation Valve (Stepper Motor) Check ).

Q. Is the check result normal?

	Go to Step 6 .

	Replace the exhaust gas recirculation valve.

STEP 6. M.U.T.-III data list

Refer to Data List Reference Table .

Item AC: Right bank oxygen sensor (front)
Item AD: Right bank oxygen sensor (rear)
Item AE: Left bank oxygen sensor (front)
Item AF: Left bank oxygen sensor (rear)

Q. Are the check results normal?

	Go to Step 7 .

	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 7. Visual check of ignition spark.

Remove the spark plug and install it to the ignition coil.
Connect the ignition coil connector.
Remove all injector connectors.
At the engine start, check each spark plug produces a spark.

Q. Is the check result normal?

	Go to Step 9 .

	Go to Step 8 .

STEP 8. Check spark plug.

Check spark plug itself (Refer to GROUP 16 - Ignition System - On-vehicle Service - Spark Plug Check and Cleaning ).

Q. Is the check result normal?

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

	Replace the spark plug.

STEP 9. Check throttle body (throttle valve portion) contamination.

Q. Is the check result normal?

	Go to Step 10 .

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

STEP 10. Check compression pressure.

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

Q. Is the check result normal?

	Go to Step 11 .

	Repair.

STEP 11. Fuel pressure measurement.

Fuel pressure measurement (Refer to ).

Q. Is the check result normal?

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

	Repair.