Posted in Mitsubishi Colt

P0300 – Random-Multiple 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).
    or
  • 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
  • Failed crank angle sensor
  • Incorrect air-fuel ratio
  • Low compression pressure
  • Failed engine coolant temperature sensor
  • Skipping of timing chain teeth.
  • Failed engine-ECU
  • Failed fuel system

    • DIAGNOSIS PROCEDURE

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

  • Item No. 3: Crank angle sensor

    • Q. Is the check result normal?

    STEP 2. M.U.T.-III data list

  • Item No. 8: Engine coolant temperature sensor
  • Item No. 19: Air-fuel ratio feedback integration
  • Item No. 20: Air-fuel ratio learning value of A zone (low load)
  • Item No. 21: Air-fuel ratio learning value of B zone (low speed load)

    • Q. Are the check results normal?

    STEP 3. 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 4. Connector check: Injector connectors

  • A-101 (No. 1 injector connector)
  • A-102 (No. 2 injector connector)
  • A-123 (No. 3 injector connector)

    • Q. Are the check results normal?

    STEP 5. Check injector itself.

    Q. Is the check result normal?

    STEP 6. Fuel pressure measurement.

    Q. Is the check result normal?

    STEP 7. Check for intake of air from gaps in gasket, seals, etc.

    Q. Is the check result normal?

    STEP 8. Check for skipped timing chain teeth.

    Q. Is the check result normal?

    STEP 9. Check compression pressure.

    Q. Is the check result normal?

    STEP 10. M.U.T.-III diagnosis code.

  • Reconfirmation of diagnosis code.

    • Q. Is the diagnosis code set?

    Author: admin