Code No. P0300: Random/Multiple Cylinder Misfire Detected




OPERATION




FUNCTION




TROUBLE JUDGEMENT


Check Conditions
Judgement Criterion (change in the angular acceleration of the crankshaft is used for misfire detection).
or


FAIL-SAFE AND BACKUP FUNCTION




PROBABLE CAUSES




DIAGNOSIS PROCEDURE


STEP 1. M.U.T.-III data list



  • Data list reference table (Refer to ).

  1. Item 2: Crank angle sensor
  2. Item 5: Intake air temperature sensor
  3. Item 6: Engine coolant temperature sensor
  4. Item 10: Air flow sensor
  5. Item 26: Long-term fuel trim
  6. Item 28: Short-term fuel trim

Q. Are the check results normal?

YES : Go to Step 2.
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 2. 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 3.
Check Inspection Procedure - ignition circuit system (Refer to ).

STEP 3. Check injector itself.



  • No.1, No.2, No.3, No.4 injector connector check.
  • Injector check (Refer to ).

Q. Are the check results normal?

Go to Step 4.
Repair or replace the connector, or replace the injector.

STEP 4. Check air intake from inlet hose and inlet manifold.


Q. Is the check result normal?

Go to Step 5.
Repair.

STEP 5. Fuel pressure measurement.



  • Fuel pressure test (Refer to )

Q. Is the check result normal?

Go to Step 6.
Repair.

STEP 6. Check for skipped timing chain teeth.


Q. Is the check result normal?

Go to Step 7.
Replace the timing chain.

STEP 7. 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 8.
Repair.

STEP 8. Replace the engine-ECU.



  • After replacing the engine-ECU, reconfirm whether the diagnosis code is stored.

Q. Is the diagnosis code stored?

Check for foreign matters (water, diesel fuel, etc.) in fuel and replace if necessary.
Check end.