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Home >> Kia >> 2021 >> Rio LX >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System Diagnosis (3 Of 6) >> DTC P0300-00: Random Multiple Cylinder Misfire Detected >> System Inspection >> Compression Pressure Inspection >> Inspection Procedure

Inspection Procedure

  1. Warm up and stop engine.
  2. Remove the engine cover.
  3. Disconnect the injector connectors.
  4. Remove the ignition coil.
  5. Remove the spark plugs. (using a 16mm plug wrench, remove the 4 spark plugs)
  6. Check the cylinder compression pressure.
    1. Insert a compression gauge into the spark plug hole.
    2. Set the throttle plate in the wide-open position.
    3. While cranking the engine, measure the compression pressure. (always use a fully charged battery to obtain engine speed of 200 RPM or more)
    4. Repeat step  1) through  3) for each cylinder. (This measurement must be done in as short time as possible.)
      • Specification: 

    Standard: 1225.83kPa (12.5kg/cm2 , 177.79psi) (200 to 250 RPM)

    Maximum: 1078.73kPa (11.0kg/cm2 , 156.46psi)

    Difference between each cylinder: 98kPa (1.0kg/cm2 , 14psi) or less

  7. Is the measured value within specifications?

    Good 

    • 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 Good 

    • 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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