Inspection Procedure 10: Hesitation, Sag, Poor Acceleration, Stumble or Surge

COMMENTS ON TROUBLE SYMPTOM

The failure could possibly be caused by the failed ignition system, improper air-fuel ratio, faulty compression pressure and so on.

PROBABLE CAUSES

Failed air-fuel ratio control system
Failed ignition system
Failed fuel system
Failed electronic-controlled throttle valve system
Contamination around the throttle valve
Improper compression pressure
Failed engine-ECU

DIAGNOSIS PROCEDURE

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

Q. Is diagnosis code stored?

	Inspection chart for diagnosis code (Refer to ).

	NO : Go to Step 2.

STEP 2. Check injector for operating sound.

Injector check (Refer to ).

Q. Is operating sound audible?

	Go to Step 3.

	Check the injector system of the defective cylinder. (Refer to P0261: No.1 injector circuit low input ). (Refer to P0262 No.1 injector circuit high input ). (Refer to P0264 No.2 injector circuit low input ). (Refer to P0265 No.2 injector circuit high input ). (Refer to P0267 No.3 injector circuit low input ). (Refer to P0268 No.3 injector circuit high input ).

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

Data list reference table (Refer to ).

Item 5: Intake air temperature sensor
Item 6: Engine coolant temperature sensor
Item 8: Manifold absolute pressure 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)
Item 36: V.V.T.phase angle

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. Inspection chart for diagnosis code (Refer to ).

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. M.U.T.-III data list

Data list reference table (Refer to ).

Item AC: Oxygen sensor (front)
Item AD: Oxygen sensor (rear)

Q. Are the check results normal?

	Go to Step 6.

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

STEP 6. Visual check of ignition spark.

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

Q. Is the check result normal?

	Go to Step 7.

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

STEP 7. Check throttle body (throttle valve portion) contamination.

Q. Is the check result normal?

	Go to Step 8.

	Throttle body (throttle valve area) cleaning (Refer to ).

STEP 8. Check compression pressure.

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

Q. Is the check result normal?

	Go to Step 9.

	Repair.

STEP 9. Fuel pressure measurement.

Fuel pressure test (Refer to ).

Q. Is the check result normal?

	Replace the engine-ECU.

	Repair.