Code No. P0304: No. 4 Cylinder Misfire Detected








OPERATION



  • Refer to Code No. P0204: No. 4 Injector System .

FUNCTION



  • If a misfire occurs while the engine is running, the engine speed changes for an instant.
  • The engine-ECU <M/T> or engine-A/T-ECU <A/T> checks for such changes in engine speed.

TROUBLE JUDGMENT


Check Conditions
  • Engine speed is 440 - 4,500 r/min.
  • Engine coolant temperature and intake air temperature are -10°C or higher.
  • Barometric pressure is 106 kPa or lower.
  • Volumetric efficiency is between 15 % and 100 %.
  • Adaptive learning is complete for the vane which generates a crankshaft position signal.
  • While the engine is running, excluding gear shifting, deceleration, sudden acceleration/deceleration and A/C compressor switching.
  • The throttle deviation is -0.06 V/10 ms to +0.06 V/10 ms.
Judgment Criterion (change in the angular acceleration of the crankshaft is used for misfire detection).
  • Misfire has occurred more frequently than the limit during the last 200 revolutions (when the catalyst temperature has been 950°C or higher).
    or
  • The misfire ratio goes beyond the permitted limit within the last 1,000 revolutions from when the exhaust gas exceeds the regulation value.

PROBABLE CAUSES



  • Ignition system related part(s) failed
  • Low compression pressure
  • Failed engine-ECU <M/T> or engine-A/T-ECU <A/T>

DIAGNOSIS PROCEDURE

STEP 1. Visual check of ignition spark.

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

Q. Is the check result normal?
Go to Step 3 .
Go to Step 2 .

STEP 2. Check spark plug.

  • Check spark plug itself (Refer to GROUP 16 - Ignition System <6G7> - On-vehicle Service - Spark Plug Check and Cleaning ).

Q. Is the check result normal?
Check ignition circuit system (Refer to Inspection Procedure 26 ).
Replace spark plug.

STEP 3. Connector check: B-105 No. 4 injector connector

Q. Is the check result normal?
Go to Step 4 .
Repair or replace the connector.

STEP 4. Check No. 4 injector itself.

  • Check injector itself (Refer to ).

Q. Is the check result normal?
Go to Step 5 .
Replace the No. 4 injector.

STEP 5. Connector check: B-15X engine control relay connector and D-243 engine-ECU <M/T> connector or D-212 engine-A/T-ECU <A/T> connector

Q. Is the check result normal?
Go to Step 6 .
Repair or replace the connector.

STEP 6. Check harness between B-15X (terminal No. 1) engine control relay connector and B-105 (terminal No. 1) No. 4 injector connector.


note Before checking harness, check intermediate connector B-48, and repair if necessary.

  • Check power supply line for damage.

Q. Is the check result normal?
Go to Step 7 .
Repair the damaged harness wire.

STEP 7. Check harness between B-105 (terminal No. 2) No. 4 injector connector and D-243 (terminal No. 21) engine-ECU <M/T> connector or D-212 (terminal No. 21) engine-A/T-ECU <A/T> connector
note Before checking harness, check intermediate connector B-48, and repair if necessary.

  • Check output line for damage.

Q. Is the check result normal?
Go to Step 8 .
Repair the damaged harness wire.

STEP 8. Fuel pressure measurement.

  • Fuel pressure measurement (Refer to ).

Q. Is the check result normal?
Go to Step 9 .
Repair.

STEP 9. Check compression pressure.

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

Q. Is the check result normal?
Go to Step 10 .
Repair the compression pressure.

STEP 10. Check the trouble symptoms.

Q. Does trouble symptom persist?
Replace the engine-ECU <M/T> or engine-A/T-ECU <A/T>.
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).