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Home >> Suzuki >> 2000 >> Vitara JS, 4D Utility, Automatic >> Repair and Diagnosis >> Engine Performance >> Testing & Diagnosis >> Engine Controls - Self-Diagnostics - Tests >> Diagnostic Tests >> DTC P0300: Random Misfire Or DTC P0301, P0302, P0303 Or P0304: Cylinders No. 1-4 Misfire

DTC P0300: Random Misfire Or DTC P0301, P0302, P0303 Or P0304: Cylinders No. 1-4 Misfire

  1. Check ignition spark and spark plug at cylinder in question. Repair as necessary. If a strong Blue spark is present at ignition wire and spark plug is okay, go to next step.
  2. Using a mechanic's stethoscope, check each fuel injector for a clicking sound while cranking engine. If sound is not heard from all 4 injectors, inspect and repair poor connections or open circuit between fuel injector(s) and PCM. If wiring and connections are okay, replace PCM and retest system. If sound is heard from all 4 injectors, go to next step.
  3. Check fuel pressure. See CIRCUIT TEST B-3: FUEL PRESSURE INSPECTION under CIRCUIT TESTS in BASIC DIAGNOSTIC PROCEDURES article. If fuel pressure is within specifications, go to next step. If fuel pressure is not as specified, repair as necessary and retest system.
  4. Check fuel injectors. See CIRCUIT TEST B-1: FUEL INJECTOR CIRCUIT INSPECTION under CIRCUIT TESTS in BASIC DIAGNOSTIC PROCEDURES article. If problem is present, repair as necessary and retest system. If fuel injectors are okay, go to next step.
  5. Check ignition timing. See IGNITION TIMING in ON-VEHICLE ADJUSTMENTS article. Adjust ignition timing as necessary and retest system. If ignition timing is okay, go to next step.
  6. Check EGR system for proper operation. See EXHAUST GAS RECIRCULATION (EGR) under EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTING article. Repair as necessary. If EGR operation is okay, go to next step.
  7. Check fuel level sensor operation. See DTC P0461: FUEL LEVEL SENSOR CIRCUIT PERFORMANCE  . Repair as necessary. If fuel level sensor operation is okay, go to next step.
  8. Inspect engine mechanical systems for proper operation. Check engine compression, valve lash adjustment and valve timing. See appropriate article in ENGINES. Repair as necessary and retest system. If engine mechanical condition is okay, check PCM, ignition and fuel system wiring harnesses for intermittent open or short circuits. Repair as necessary.
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