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Home >> Hyundai >> 2001 >> Tiburon Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P0300: Random Misfire Detected >> Test Procedures
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Test Procedures

  1. Check if DTC P0300 is the only DTC set. If other DTCs are set, repair other DTCs first. When repairs are completed, clear DTC and verify operation. If only DTC P0300 is set, go to next step.
  2. Turn ignition off. Check fuel octane. If fuel octane is 87 or more, go to next step. If fuel octane is less than 87, refuel with 87 or higher octane fuel and retest, clear DTC and verify operation.
  3. Disconnect ignition coil 3-pin connector. Turn ignition on. Measure voltage between ground and ignition coil connector terminal No. 1 (Brown wire). If battery voltage exists, go to next step. If battery voltage does not exist, repair open in Brown wire between ignition switch 6-pin connector terminal No. 4 and ignition coil connector terminal No. 1. When repairs are completed, clear DTC and verify operation.
  4. Turn ignition off. Disconnect ECM 88-pin connector. Using jumper wires, ground ignition coil connector terminals No. 2 (Green wire) and No. 3 (White wire). Measure resistance between ground and ECM connector terminals No. 25 (Green wire) and No. 52 (White wire). See Figure . If resistance is one ohm or less, remove jumper wires and go to next step. If resistance is more than one ohm, repair open in Green wire or White wire between ignition coil and ECM. When repairs are completed, clear DTC and verify operation.
  5. Reconnect ECM connector. Turn ignition switch to START position. Measure voltage between ground and ignition coil connector terminals No. 2 (Green wire) and No. 3 (White wire). Voltage should vary between 0.02 volt and 0.20 volt. If each voltage is as specified, go to next step. If either voltage is not as specified, ensure ECM connector terminals are clean and tight. If connector is okay, replace ECM. When repairs are completed, clear DTC and verify operation.
  6. Turn ignition off. Disconnect spark plug wires from coil. Measure primary coil resistance between ignition coil terminals No. 1 and 2 (component side), and between ignition coil terminals No. 1 and 3 (component side). Primary coil resistance should be about one ohm. If primary coil resistance is as specified, go to next step. If primary coil resistance is not as specified, replace ignition coil. When repairs are completed, clear DTC and verify operation.
  7. Measure resistance of secondary coils between ignition coil spark plug wire towers No. 1 and 4, and between ignition coil spark plug wire towers No. 2 and 3. Secondary coil resistance should be 10,300-13,900 ohms. If secondary coil resistances are as specified, go to next step. If either secondary coil resistance is not as specified, replace ignition coil. When repairs are completed, clear DTC and verify operation.
  8. Inspect the following components/systems and ensure they are operating properly:
    • Spark plugs and spark plug wires.
    • Clogged, leaking or damaged fuel injectors and wiring.
    • Obstructed airflow meter.
    • Acceleration sensor wiring harness.
    • Canister purge valve.
    • Vacuum hoses and connections.

    If problem does not exist, go to next step. If problem exists, repair or replace components/systems as necessary. When repairs are completed, clear DTC and verify operation.

  9. Perform fuel pressure inspection. See FUEL PRESSURE TEST under FUEL SYSTEM in BASIC DIAGNOSTIC PROCEDURES article. If fuel pressure is not as specified, repair fuel system as necessary. If fuel pressure is within specification and no pressure leak-down is detected, check engine oil for proper level and for contamination (fuel or water in oil). If engine oil is okay, ensure ECM connector terminals are clean and tight. If ECM connector is okay, replace ECM. When repairs are completed, clear DTCs and verify operation.
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