Posted in Mitsubishi Colt

P0303 – No. 3 Cylinder Misfire Detected MMC Colt

 Posted by  Posted on September 26, 2020

FUNCTION

  • If a misfire occurs while the engine is running, the engine speed changes for an instant.
  • The engine-ECU checks for such changes in engine speed.

    • TROUBLE JUDGMENT

  • Engine speed is 500 – 6,500 r/min.
  • Engine coolant temperature is -10°C or higher.
  • Barometric pressure is 76 kPa or higher.
  • Volumetric efficiency is between 30 % and 55 %.
  • 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.
  • Misfire has occurred more frequently than the limit during the last 200 revolutions (when the catalyst temperature has been 950°C or higher).
  • Misfire has occurred 15 times or more in the last 1,000 revolutions (that has been equivalent to approximately 1.5 times the emission standard).

    • PROBABLE CAUSES

  • Ignition system related part(s) failed
  • Low compression pressure
  • Failed engine-ECU
  • Failed fuel system
  • Harness damage in No. 3 injector circuit, or connector damage

    • DIAGNOSIS PROCEDURE

    STEP 1. Visual check of ignition spark.

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

    • Q. Is the check result normal?

    STEP 2. Connector check: A-123 No. 3 injector connector

    Q. Is the check result normal?

    STEP 3. Check No. 3 injector itself.

    Q. Is the check result normal?

    STEP 4. Connector check: B-206 engine control relay connector and A-08 engine-ECU connector

    Q. Is the check result normal?

    STEP 5. Check harness between B-206 (terminal No. 4) engine control relay connector and A-123 (terminal No. 1) No. 3 injector connector.

  • Check power supply line for damage.

    • Q. Is the check result normal?

    STEP 6. Check harness between A-123 (terminal No. 2) No. 3 injector connector and A-08 (terminal No. 23) engine-ECU connector

  • Check earthing line for damage.

    • Q. Is the check result normal?

    STEP 7. Fuel pressure measurement.

    Q. Is the check result normal?

    STEP 8. Check compression pressure.

    Q. Is the check result normal?

    STEP 9. M.U.T.-III diagnosis code

  • Reconfirmation of diagnosis code.

    • Q. Is the diagnosis code set?

    Author: admin