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Home >> Mitsubishi >> 2003 >> Eclipse RS, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics - 2.4L >> Diagnostic Tests >> DTC P0300: Random/Multiple Misfire Detected >> Diagnostic Procedure
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Diagnostic Procedure

CAUTION: To prevent damage to scan tool (MB991502), always turn the ignition off before connecting or disconnecting it.
  1. Connect scan tool (MB991502) to the data link connector. Start the engine and run at idle. Set the scan tool to data reading mode for item 22, Crankshaft Position Sensor. Check the waveform of the crankshaft position sensor while keeping the engine speed constant. The pulse width should be constant. Turn the ignition off. If the sensor is operating properly, go to the next step. If the sensor is malfunctioning, refer to DTC P0335: CRANKSHAFT POSITION (CKP) SENSOR CIRCUIT MALFUNCTION  .
  2. Start the engine and run at idle. Set the scan tool to data reading mode for item 81, Long-Term Fuel Compensation (trim). The fuel trim should be between -12.5 and +12.5 when the load is 2,500 RPM (during closed loop) after the engine is warmed. Turn the ignition off. If the specification is normal, go to the next step. If the specification is abnormal, refer to DTC P0171: SYSTEM TOO LEAN  or DTC P0172: SYSTEM TOO RICH  .
  3. Start the engine and run at idle. Set the scan tool to data reading mode for item 82, Short-Term Fuel Compensation (trim). The fuel trim should be between -25 and +25 when the load is 2,500 RPM (during closed loop) after the engine is warmed. Turn the ignition off. If the specification is normal, go to the next step. If the specification is abnormal, refer to DTC P0171: SYSTEM TOO LEAN  or DTC P0172: SYSTEM TOO RICH  .
  4. Check each ignition coil spark. Remove the intake manifold. Remove the spark plug and connect the spark plug cable. Ground the spark plug side electrode securely. When the engine is cranked, the spark plug should spark. If the plug sparked, proceed to step  7 , otherwise, go to the next step.
  5. Check the spark plugs. Check that the plugs are not burned, that the insulator plug is not damaged, and that the seizure state is good. If cleaning is required due to carbon deposits, etc., clean using a plug cleaner or wire brush, etc. Check the plug gap using a gap gauge, and adjust if not within the standard value. Standard value: 1.0-1.1 mm (0.039-0.043 inch). If the spark plug is in good condition, go to the next step. If the spark plug is damaged, replace the faulty spark plug and proceed to step  13 .
  6. Check the spark plug cable. Check the cap and coating for cracks. Measure the resistance. Limit: maximum 19 kohm. If the resistance is normal, do a thorough check of the ignition circuit system. If the resistance is abnormal, replace the faulty spark plug cable, and proceed to step  13 .
  7. Check the injector. Disconnect the injector connector. Measure the resistance between each injector side connector terminals No. 1 and 2. Standard value: 13-16 ohm at 68°F (20°C). If the resistance is at the standard value, go to the next step. If the resistance is abnormal, replace the faulty injector and proceed to step  13 .
  8. Check connector B-01, B-02, B-05, B-06 at injector for damage. If the connector is in good condition, go to the next step. If the connector is damaged, repair or replace the faulty injector and proceed to step  13 .
  9. Check connector C-49 at ECM (M/T) or connector C-50 at PCM (A/T) for damage. If the connector is in good condition, go to the next step. If the connector is damaged, repair or replace it and proceed to step  13 .
  10. Check for harness damage between injector connector and ECM connector (M/T) or PCM connector (A/T).
    1. Check the harness wire between injector connector B-01 terminal No. 2 and ECM connector C-49 terminal No. 1 (M/T) or PCM connector C-50 terminal No. 1 (A/T) when checking No. 1 cylinder.
    2. Check the harness wire between injector connector B-02 terminal No. 2 and ECM connector C-49 terminal No. 14 (M/T) or PCM connector C-50 terminal No. 9 (A/T) when checking No. 2 cylinder.
    3. Check the harness wire between injector connector B-05 terminal No. 2 and ECM connector C-49 terminal No. 2 (M/T) or PCM connector C-50 terminal No. 24 (A/T) when checking No. 3 cylinder.
    4. Check the harness wire between injector connector B-06 terminal No. 2 and ECM connector C-49 terminal No. 15 (M/T) or PCM connector C-50 terminal No. 2 (A/T) when checking No. 4 cylinder.
    If the harness wire is in good condition, go to the next step. If the harness wire is damaged, repair it and proceed to step  13 .
  11. Check for skipped timing belt teeth, compression and EGR valve functionality. If there are any abnormalities, rectify and proceed to step  13 . If there are no problems, go to the next step.
  12. Replace the injector. Carry out a test drive with the drive cycle pattern, refer to OTHER MONITOR  . Check the diagnostic trouble codes. If DTC P0300 is output, replace the ECM or PCM and go to the next step. If the DTC is absent, the inspection is complete.
  13. Carry out a test drive with the drive cycle pattern, refer to OTHER MONITOR  . Check the diagnostic trouble codes. If DTC P0300 is output, retry the troubleshooting. If the DTC is absent, the inspection is complete.
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