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Home >> Hyundai >> 2002 >> Accent GL, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P0300: Random Misfire Detected >> Test Procedure

Test Procedure

  1. Turn ignition off. Connect Hi-Scan Pro tool or equivalent to OBD-II Data Link Connector (DLC). See Figure. Turn ignition on. Monitor and verify than DTCs P0300 is the only one set and go to next step. If other DTCs are set, do all repairs associated with those DTCs before continuing with this procedure.
  2. Ensure vehicle is fueled with at least 87 octane fuel. If vehicle is fueled as specified, go to next step. If vehicle is not fueled as specified, refuel with 87 or higher octane fuel and go to step  11.
  3. Turn ignition off. Disconnect ignition coils 2-pin harness connectors. See Fig 1. Turn ignition on. Measure voltage between ground and ignition coils connector terminal No. 1 (Orange wire). Voltage should be battery voltage. If voltage is as specified, go to next step. If voltage is not as specified, repair open or short circuit (in Orange) between ignition switch and ignition coil. After repair go to step  11.
  4. Turn ignition off. Leave ignition coils harness connectors disconnected and disconnect ECM 81-pin harness connector. See Figure. Measure resistance between ignition coil-1 connector terminal No. 2 and ECM connector terminal No. 2 (Blue wire). Also measure resistance between ignition coil-2 connector terminal No. 2 and ECM connector terminal No. 5 (Brown wire). Resistance should be one ohm or less. If resistance is as specified, go to next step. If resistance is not a specified, repair open or short circuit (in Blue wire) or (in Brown wire) between ignition coil and ECM. After repair go to step  11.
  5. Reconnect ECM harness connector and leave ignition coils harness connector disconnected. While ignition switch is on START position, measure voltage between ignition coils harness connector No. 2 (Blue wire) or (Brown wire). voltage should vary between 0.02-0.2 volts. If voltage is as specified, go to next step. If voltage is not as specified, verify than ECM connector is secure. If connector is okay, replace ignition coil and retest system. If problem persist replace ECM with known-good component. After repair go to step  11.
  6. Turn ignition off. With ignition coils harness connector disconnected. Measure primary coil resistance between ignition coil connector terminal No. 1 and 2 (component side). Resistance should be approximately one ohm. Disconnect spark plug wires from ignition coils. Measure secondary coils resistance between ignition coils spark plug wires connectors No. 1 and 4, also between No. 2 and 3. Resistance should be between 10.3-13.9 k/ohms. If both resistances are as specified, go to next step. If any resistance is not as specified, replace ignition coil with known-good component. After repair go to step  11.
  7. Perform an inspection of following systems and components:
    • Spark plug and spark plug wires for cracks or damage.
    • Fuel injectors clogging or wiring damage.
    • Obstruction of Mass Air Flow (MAF) sensor.
    • Acceleration sensor wiring or connection damage.
    • EVAP Canister Control Valve for proper operation.
    • Vacuum hoses for damage or leaks.

    If all components are in good operation condition, go to next step. If any component is faulty, repair or replace as necessary and go to step  11.

  8. Return vehicle to original condition and perform fuel pressure test. Release fuel pressure from fuel system. See FUEL PRESSURE RELEASE . Install fuel pressure gauge. See FUEL PRESSURE TEST in BASIC DIAGNOSTIC PROCEDURES article. Fuel pressure should be 49.8 psi (3.5 kg/cm2 ). If fuel pressure is as specified, go to next step. If fuel pressure is not as specified, follow diagnose and repair procedures under fuel pressure test and go to step  11.
  9. Turn ignition off. Check engine oil for improper level or contamination (fuel in oil). If engine oil level and condition are okay, go to next step. If engine oil level and conditions are faulty, determine source of oil contamination and improper level, repair and replace as necessary and go to step  11.
  10. Verify than MFI system components and ECM connectors are secure. If components and connectors are okay, replace ECM with known-good component and go to next step.
  11. Return vehicle to original condition. Clear codes using Hi-Scan Pro tool or equivalent. Verify repairs by driving vehicle and monitoring for pending codes. If DTC is set during test drive, follow appropriate DTC test procedure.
Fig 1: Identifying Ignition Coil Connector Terminals
G00140021Courtesy of HYUNDAI MOTOR CO.
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