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Home >> Mitsubishi >> 2000 >> Eclipse RS, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P0300: Random Misfire Detected >> Diagnostic Procedures
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Diagnostic Procedures

  1. Connect scan tool to OBD-II Data Link Connector (OBD-II DLC), located below center of instrument panel. Start engine and let idle. Using scan tool, check data list item No. 22 (crankshaft position sensor). Check CKP sensor pulse width with engine speed constant. If CKP sensor pulse width is constant, go to next step. If CKP sensor pulse width is not constant, check CKP sensor circuit. See DTC P0335: CRANKSHAFT POSITION (CKP) SENSOR CIRCUIT MALFUNCTION  .
  2. Start and warm-up engine. Turn all accessories off. Increase engine speed to 2500 RPM. Read scan tool data list item No. 81 (long-term fuel compensation). At 2500 RPM in closed loop, fuel trim should be -12.5-12.5 percent. If fuel trim is as specified, go to next step. If fuel trim is not as specified, check fuel trim fault. See DTC P0170 OR P0173: FUEL TRIM MALFUNCTION  .
  3. Read scan tool data list item No. 82 (short-term fuel compensation). At 2500 RPM in closed loop operation, fuel trim should be -10-10 percent. If fuel trim is as specified, go to next step. If fuel trim is not as specified, check fuel trim fault. See DTC P0170 OR P0173: FUEL TRIM MALFUNCTION  .
  4. Remove spark plug and connect to plug wire. Ground spark plug electrode and crank engine. Check each plug. If spark plugs fire when engine is cranked, go to step  7 . If spark plug does not fire, go to next step.
  5. Check spark plug gap. Gap should be .039-.043" (1.0-1.1 mm). Adjust gap or replace plugs as necessary, then go to step  13 . If gap is okay, go to next step.
  6. Remove plug wires and check resistance. Maximum resistance for each plug wire is 22 k/ohms. Replace plug wires as necessary, then go to step  13 . If plug wires are okay, check ignition circuit. See IGNITION CHECKS in BASIC DIAGNOSTIC PROCEDURES article.
  7. Disconnect fuel injector connectors. Check resistance between fuel injector terminals. Resistance should be 13-16 ohms at 68°F (20°C). If each resistance is as specified, go to next step. If any resistance is not as specified, replace faulty fuel injector(s), then go to step  13 .
  8. Check fuel injector connectors. Repair as necessary, then go to step  13 . If fuel injector connectors are okay, connect fuel injector connectors, then go to next step.
  9. Check ECM/PCM connectors. Repair as necessary, then go to step  13 . If connectors are okay, go to next step.
  10. Check wiring between fuel injectors and ECM/PCM. Repair as necessary, then go to step  13 . If wiring is okay, go to next step.
  11. Check camshaft timing. See appropriate article in ENGINES. Check engine compression. See MECHANICAL INSPECTION under PRELIMINARY INSPECTION & ADJUSTMENTS in BASIC DIAGNOSTIC PROCEDURES article. Check EGR system. See EMISSIONS SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTING article. Repair as necessary, then go to step  13 . If no problem exists, go to next step.
  12. Replace appropriate fuel injectors. Remove all test equipment and install all disconnected/removed components. Using scan tool, clear DTCs. Test drive vehicle following other monitor drive cycle pattern. See OBD-II DRIVE CYCLES under VERIFYING REPAIRS in SELF-DIAGNOSTICS - INTRODUCTION article. Check for DTCs. See VERIFYING REPAIRS in SELF-DIAGNOSTICS - INTRODUCTION article. If DTC P0300 is not output, inspection is complete. If DTC P0300 is output, replace ECM/PCM, then go to next step.
  13. Remove all test equipment and install all disconnected/removed components. Using scan tool, clear DTCs. Test drive vehicle following other monitor drive cycle pattern. See OBD-II DRIVE CYCLES under VERIFYING REPAIRS in SELF-DIAGNOSTICS - INTRODUCTION article. Check for DTCs. Confirm DTC P0300 does not reset. See VERIFYING REPAIRS in SELF-DIAGNOSTICS - INTRODUCTION article.
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