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Home >> Hyundai >> 2009 >> Elantra GLS, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> DTC Troubleshooting Procedures >> DTC P0300 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. Verify the battery must be at or near full charge.
  2. With ignition "OFF", disconnect the ignition coil connectors and the spark plug cables
  3. Install compression pressure gauge to the spark plug hole.
  4. With wide open throttle by hand, cranking the engine and record the compression readings from all of the cylinders

    Specification: 

    Compression pressure: 1,283kPa (13.0kgf/cm2 , 185psi)

    Minimum pressure: 1,135kPa (11.5kgf/cm2 , 164psi)

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

  5. Is compression pressure within the specified value?

    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 VEHICLE 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 VEHICLE REPAIR " procedure