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Home >> Kia >> 2016 >> Forte5 SX, Automatic Trans >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System Diagnosis - 1.6L (2 Of 3) >> DTC P0300: Random/Multiple Cylinder Misfire Detected >> System Inspection
July 1: So it begins. Don't worry, this is not in the correct legal jurisdiction!

System Inspection

■ Spark Plug Check 

  1. Remove the 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 lists?

    YES 

    NO 

    • Go to "Compression Pressure Check" procedure.

■ Compression Pressure Check 

  1. Warm up the engine to normal operating temperature.
  2. Remove the fuel pump fuse(15A).
  3. Wait until the engine stopped.
  4. Remove the ignition coils and spark plugs.
  5. Crank the engine to remove any foreign material in the cylinders.
  6. Put a compression pressure gauge into spark plug hole.
  7. Check compression pressure at each cylinder.

    Specification:  Approx. 15kg/cm2

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

    YES 

    • Go to "Ignition System Check" procedure.

    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 compressions at each cylinders are not same or not similar, a burnt or defective valve seat, worn head gasket and pressure rings can be the cause of vibration of engine. Repair as necessary and go to "Verification Of Vehicle Repair " procedure.

■ Ignition System Check 

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

    Specification:  Approx 12V

  6. Connect ignition coil harness connectors to the ignition coils.
  7. Compare with the below reference value and ignition primary waveform and determine whether the values are normal or not.
    Fig 1: Screen Display - Signal Waveform Of Ignition Coil
    G11797939Courtesy of KIA MOTORS AMERICA, INC.
  8. Is the measured voltage within specifications?

    YES 

    • Go to "Check Injector Performance" procedure.

    NO 

    • Substitute with a known-good IG Coil and check for proper operation. If the problem is corrected, replace IG Coil and then go to "Verification Of Vehicle Repair " procedure.

■ Check Injector Performance 

  1. IG KEY "OFF".
  2. Connect CH A probe to control terminal of Injector (Highside) and CH B probe to control terminal of Injector(Low side).
  3. Connect CH AUX probe to control wire of Injector.
  4. Warm up the engine to normal operating temperature.

    Specification:  Refer to SIGNAL WAVEFORM & DATA 

    Fig 2: Screen Display - Signal Waveform Of Injector
    G11797940Courtesy of KIA MOTORS AMERICA, INC.

    CH. A - Injector high Max 65.3V

    CH. B - Injector Low Max 65.3V

    CH. AUX - Injector Current MAX 9.12A

  5. Does the injector operate properly?

    YES 

    NO 

    • Substitute with a known-good Injector and check for proper operation. If the problem is corrected, replace Injector and then go to "Verification Of Vehicle Repair " procedure.
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