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Home >> Kia >> 2015 >> Forte LX, Automatic Trans >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System Diagnosis (1 Of 2) - 1.8L >> DTC P0300: Random Multiple Cylinder Misfire Detected >> System Inspection >> Ignition System Inspection
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Ignition System Inspection

  1. Misfire Inspection
    1. Check the cylinder where the misfire occurs after replacing the ignition coil of the cylinder where the misfire has occurred with the ignition coil of the other cylinder.
    2. Does the misfiring cylinder change?

      YES 

      • Go to "ignition Coil Waveform Inspection" procedure.

      NO 

  2. Ignition coil waveform inspection
    1. Ignition "ON" and engine "ON".
    2. Measure the voltage between control terminal of ignition soil harness connector and chassis ground.

      Specification:  Refer to Waveform

      Fig 1: Engine Idle After Warm Up Waveform
      G00570727Courtesy of KIA MOTORS AMERICA, INC.

      Spark retention time - Approx. 1.2ms

      CH. A - Ignition Max 31V

    3. Is the measured waveform within specification?

      YES 

      Repair as necessary except for the ignition coils and go to "FUEL SYSTEM INSPECTION " procedure.

      NO 

      Go to "Spark Plug Cable & Ignition Coil Inspection" procedure.

  3. Spark Plug Cable & Ignition Coil Inspection
    1. Visually/physically inspect the spark plug cable and ignition coil related to the misfiring cylinder(s) for the following conditions.
      • Damage, cracks, carbon and flashover
      • Poor connection or damaged harness
      • Connected to the incorrect cylinders at the ignition coil and spark plug
    2. Measure the resistance of the spark plug cable related to the misfiring cylinder(s)

      Specification:  5.6kΩ/m ±20%

    3. Measure the resistance of the primary and secondary ignition coil related to the misfiring cylinder(s)

      Specification:  Primary Ignition Coil Resistance : 0.56~0.68Ω at 20°C(68°F)

      Secondary Ignition Coil Resistance : 6~8kΩ at 20°C(68°F)

    4. Was a problem found in any of the above areas?

      YES 

      NO 

      • Go to next step as below.
  4. Spark Plug Inspection
    1. Visually/physically inspect the spark plug related to the misfiring cylinder(s) for the following conditions.
      • Damaged insulation, Worn electrodes, Oil or fuel fouled, Loose terminals and cracks.
      • Check for electrode gap : 1.0 - 1.1 mm (0.039 - 0.043 in.)
      • Check if the spark plug for the relevant cylinder is lighter in color than the other plugs.
    2. Was a problem found in any of the above areas?

      YES 

      NO 

      • Go to next step as below.