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Home >> Hyundai >> 2015 >> Accent GS, Automatic Trans >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System Diagnosis (1 Of 2) >> DTC P0300: Random/Multiple Cylinder Misfire Detected >> System Inspection >> System Inspection
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System Inspection

■ Spark Plug Check 

  1. Remove cylinder's spark plugs.
  2. Visually/Physically inspect the following items:
    • Damaged insulation, Worn electrodes, Oil or fuel fouled, Loose terminals and cracks.
    • Check for plug gap: 0.9 - 1.0 mm (0.035 - 0.039 in.).
    • Check if the spark plug for the relevant cylinder is lighter in color than the other plugs.
  3. Has a problem been found in any of the above areas?

    YES 

    NO 

■ Compression Pressure Check 

  1. Warm up the Engine to normal operating temperature.
  2. Disconnect the spark plug cables. And remove the spark plugs and fuel pump relay.
  3. Crank the Engine to remove any foreign material in the cylinders.
  4. Put compression pressure gauge into spark plug hole.
  5. Check compression pressure at each cylinder.

    Specification:  Approx. 15kg/cm2

  6. Is compression pressure for each cylinder displayed within specifications?

    YES 

    NO 

    • Add a small amount of oil through the spark plug hole, and repeat above steps. If the addition of oil causes the compression to rise, the cause is a worn or damaged piston ring or cylinder inner surface.
    • If the compression remains the same, the cause is a burnt or defective valve seat, or pressure is leaking from the gasket. Repair as necessary and go to "VERIFICATION OF VEHICLE REPAIR " procedure.

■ Ignition System Check 

  1. IG KEY "OFF".
  2. Disconnect Ignition Coil connector.
  3. Do visual inspection.
    • Check contamination or damage on ignition coil.
  4. IG KEY "ON" & ENG "OFF"
  5. Measure the voltage between power terminal of ignition coil #1, #2, #3, #4 harness connector and chassis ground.

    Specification:  B+

  6. Is the measured voltage within specifications?

    YES 

    NO 

    ■ Ignition Coil Check 

    1. Measure the resistance between power and control terminal of ignition coil connector #1, #2, #3, #4. (Component Side/Primary Coil).

      Specification: 

      Item Specification
      Primary Coil Resistance (Ω) 0.75Ω ± 15% [20 °C 68 °F]
    2. Is the measured resistance within specifications?

    YES 

    NO 

    • Substitute with a known - good ignition coil and check for proper operation. If the problem is corrected, replace ignition coil and go to "VERIFICATION OF VEHICLE REPAIR " procedure.

■ Timing Mark Check 

  1. IG KEY "OFF".
  2. Check the timing mark.
  3. Is the timing mark normal?

    YES 

    NO 

■ Air Leakage Check 

  1. Visually/Physically inspect the air leakage in Intake/Exhaust system as following items,
    • Vacuum hoses for splits, kinks and improper connections.
    • Throttle body gasket
    • Gasket between intake manifold and cylinder head
    • Seals between intake manifold and fuel injectors
    • Exhaust system between HO2S and Three way catalyst for air leakage.
  2. Has a problem been found in any of the above areas?

    YES 

    NO 

■ PCV (Positive Crankcase Ventilation) Valve Check 

  1. IG KEY "OFF".
  2. Disconnect PCV Valve.
  3. Check the movement of plunger by putting in and out a thin stick.
  4. Is the movement of plunger normal?

    YES 

    NO 

    • Substitute with a known - good PCV valve and check for proper operation. If the problem is corrected, replace PCV Valve and go to "VERIFICATION OF VEHICLE REPAIR " procedure.

■ Injector Check 

  1. IG KEY "OFF".
  2. Remove injectors.
  3. Check leakage or clog on injectors.
  4. Measure the resistance between power and control terminal of the injector (Component Side).

    Specification: 

    Coil Resistance (Ω) Temp (°C) Temp (°F)
    1.25 20 68
  5. Is the measured resistance within specification?

    YES 

    NO 

    • Substitute with a known - good injector and check for proper operation. If the problem is corrected, replace injector and go to "VERIFICATION OF VEHICLE REPAIR " procedure.

■ Fuel Line Check 

  1. Check clog, contamination and damage on fuel line.
    • Splits, kinks and improper connections of fuel line pipe.
    • Interference, damage and improper connections of vacuum hose on fuel line.
    • Improper connection of connectors on fuel line.
  2. Is the Fuel Line normal?

    YES 

    NO 

■ Fuel Pressure Check 

  1. IG KEY "OFF".
  2. Disconnect a Fuel Pump Relay.
  3. Engine start and wait until Engine stop. and then key "OFF".
  4. Install fuel pump relay.
  5. Connect fuel pressure gauge using the correct adaptor.
  6. Start the Engine, and record fuel pressure.

    Specification:  429 ~ 469 kPa (4.38 ~ 4.79 kgf/cm2 , 62.3 ~ 68.1 psi).

  7. Is the fuel pressure normal?

    YES 

    • Many malfunctions in the electrical system are caused by poor harness(es) and terminals. Faults can also be caused by interference from other electrical systems, and mechanical or chemical damage. So, check poor connections and the related circuit between ECM and component thoroughly. Repair as necessary and go to "VERIFICATION OF VEHICLE REPAIR " procedure.

    NO 

    • Check clogging on the fuel filter.
    • Check the fuel supply and return line.
    • Repair as necessary and go to "VERIFICATION OF VEHICLE REPAIR " procedure.