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Home >> Kia >> 2019 >> Optima EX >> Repair and Diagnosis (Single Page) >> Engine Performance >> System >> Engine Control System Diagnosis (3 Of 6) (PHEV) >> DTC P0300-00: Random/Multiple Cylinder Misfire Detected >> System Inspection >> Engine Compression Test
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Engine Compression Test

  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: 

    Compression pressure: 980.6 kPa (10.0 kgf/cm2 , 142.2 psi)/200 to 250 rpm

    Minimum pressure: 833.5 kPa (8.5 kgf/cm2 , 120.8 psi)

    Difference between each cylinder: 100 kPa (1.0 kgf/cm2 , 15 psi) or less

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

    YES 

    • Verify if the engine has excessive coolant consumption. If yes, check for damaged inlet water passage, engine block, cylinder head or head gasket. Repair or replace as necessary and go to "VERIFICATION OF REPAIR " procedure.

    NO 

    • If the cylinder compression in 1 or more cylinders is low, pour a small amount of engine oil into the cylinder through the spark plug hole and repeat compression test for cylinders with low compression pressure.
      • If adding oil helps the compression, it is likely that the piston rings and/or cylinder bore are worn or damaged.
      • If pressure stays low, a valve may be sticking or seating is improper, or there may be leakage past the gasket. Repair or replace as necessary and go to "VERIFICATION OF REPAIR " procedure.
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