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

Test Procedures

  1. Check if other DTCs are set in addition to DTC P0300. If DTC P0300 is the only DTC set, go to next step. If other DTCs are set, repair other DTCs first. Clear DTC and verify operation.
  2. Check if vehicle is fueled with at least 87 octane fuel. If fuel is at least 87 octane, go to next step. If fuel is less than 87 octane, refuel with 87 or higher octane fuel, clear DTC and verify operation.
  3. Turn ignition off. Disconnect ignition coil connector. Turn ignition on. Measure voltage between ground and ignition coil connector terminal No. 1 (Orange wire). If battery voltage exists, go to next step. If battery voltage does not exist, repair open in Orange wire between ignition switch 6-pin connector terminal No. 4 and ignition coil. When repairs are completed, clear DTC and verify operation.
  4. Turn ignition off. Disconnect ECM 63-pin connector. For each ignition coil, connect a jumper wire between ground and ignition coil connector terminals No. 2 (coil No. 1 - Blue wire; coil No. 2 - Brown wire). Measure resistance between ground and ECM connector terminal No. 2 (coil No. 1 - Blue wire) and No. 5 (coil No. 2 - Brown 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 wire between ignition coil and ECM. When repairs are completed, clear DTC and verify operation.
  5. Reconnect ECM connector. For each ignition coil, hold ignition switch in START position and measure voltage between ground and ignition coil connector terminal No. 1 (Orange wire). Voltage should vary between 0.02-0.2 volt. If voltage is as specified on each circuit, go to next step. If voltage is not as specified on either circuit, 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. For each ignition coil, measure primary coil resistance between ignition coil connector terminals No. 1 and 2 (component side). For each ignition coil, measure secondary ignition coil resistance between ignition coil spark plug connector terminals. Primary coil resistance should be about one ohm. Secondary ignition coil resistance should be 10,300-13,900 ohms. If resistances are as specified, go to next step. If any resistance is not as specified, replace ignition coil. When repairs are completed, clear DTC and verify operation.
  7. 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.
    • Obstructions to airflow meter.
    • Acceleration sensor wiring harness.
    • Canister purge valve for normal operation.
    • Vacuum hoses and connections.

    If all components/systems are operating properly, go to next step. If any component/system is not operating properly, repair or replace components/systems as necessary. When repairs are completed, clear DTC and verify operation.

  8. Perform fuel pressure inspection. For procedure, see FUEL PRESSURE TEST under FUEL SYSTEM in BASIC DIAGNOSTIC PROCEDURES article. Fuel pressure should be 49.8 psi (3.5 kg/cm2 ). 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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