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Home >> Hyundai >> 2006 >> Azera SE >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System Diagnosis (1 Of 2) >> DTC Troubleshooting Procedures >> DTC P0300 Random/Multiple Cylinder Misfire Detected >> System Inspection
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System Inspection

  1. Check Spark Plug
    1. Remove cylinder' s 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: 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.
    3. Has a problem been found in any of the above areas?

      YES 

      NO 

      • Go to  2 "Check Air Leakage"as below
  2. Check Air Leakage
    1. Visually/physically inspect the air leakage in intake/exhaust system as following items,
      • Vacuum hoses for splits, kinks and improper connections.
      • Throttle body gasket
      • Gasket between intake manifold and cylinder head
      • Seals between intake manifold and fuel injectors
      • Exhaust system between HO2S and Three way catalyst for air leakage
    2. Has a problem been found in any of the above areas?

      YES 

      NO 

      • Go to  3 "Check for air leakage in Positive Crankcase Ventilation Valve (PCV)
  3. Check for air leakage in Positive Crankcase Ventilation Valve (PCV)
    1. Remove PCV valve from cylinder head cover by puling ventilation hose
    2. With engine idling block PCV valve opening
    3. Verify that vacuum is felt
    4. Remove PCV valve
    5. Blow through valve from port "A" and verify that air comes out of port "B"
    6. Blow through valve from port "B" and verify that no air comes out of port "A"
    7. Has a problem been found ?

      YES 

      NO 

      • Go to  4 "Check Compression pressure" as below
  4. Check Compression pressure
    1. Warm up the engine to normal operating temperature
    2. Disconnect the spark plug cables and remove the spark plugs.
    3. Crank the engine to remove any foreign material in the cylinders.
    4. Put compression pressure gauge into spark plug hole
    5. Crank the engine with widely upend throttle valve and check compression pressure at each cylinder
    6. Is compression pressure for each cylinder displayed within specifications ?

      Specification: 1323kPa (13.5 kg/cm2 ,192 psi)

      YES 

      • Go to  5 "Check Timing" as below

      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 compression remains the same, the cause is a burnt or defective valve seat, or pressure is leaking from the gasket. Repair as necessary and go to "VERIFICATION OF VEHICLE REPAIR " procedure
  5. Check Timing
    1. Ignition "OFF"
    2. Check that Cam, Crank and Oil pump sprocket timing marks are correctly in alignment
    3. Monitor these signal waveforms from CAM and Crank shaft position Sensor are correctly in alignment
      Fig 1: Signal Waveform Graph
      G04879832Courtesy of HYUNDAI MOTOR CO.
    4. Are all timing marks aligned correctly ?

      YES 

      • Go to " 6" as below

      NO 

  6. Check Fuel Pressure
    NOTE:
    • Be cautious that fuel is explosive and an empty fuel tank can still contain explosive gases. When working on fuel system, make sure to supply ventilation to the work area. Do not smoke, and keep sparks and open flames away.
    • The fuel system remains under pressure when the engine is not running. Release fuel system pressure before disconnecting any fuel line to reduce the chance of personal injury or fire damage to vehicle components.
    1. Start the engine and disconnect the fuel pump relay.
    2. Wait until fuel in fuel line is exhausted and the engine stalls.
    3. Turn the ignition switch OFF position.
    4. Install the special service tool for measuring the fuel pressure between the delivery pipe and the fuel pump relay.
    5. With fuel pressure applied, check that there is no fuel leakage from the fuel pressure gauge or connection part.
    6. Start the engine and measure the fuel pressure at idle.

      7. Specifications: 374 ~ 384 kpa (3.82 ~ 3.92 kg/cm2 , 54.3 ~ 55.8 psi)

    7. Stop the engine and check for a change in the fuel gauge reading.

      Specifications: After engine stops, the gauge reading should hold for about 5 minutes.

    8. Is the measured fuel pressure within specifications?

      YES 

      • Substitute with a known - good PCM and check for proper operation. If the problem is corrected, replace PCM and go to "VERIFICATION OF VEHICLE REPAIR " procedure.
      NOTE: There is a memory reset function on scantool that can erase optional parts automatically detected and memorized by PCM. After testing PCM on the vehicle, use this function to reuse the PCM on the others

      NO 

      • Repair or replace according to the table below.
      CONDITION AND POSSIBLE CAUSES

      Condition Possible Cause Suspected area
      Fuel pressure too low Clogged fuel filter Fuel filter
      Fuel leak on the fuel-pressure regulator that is assembled in fuel pump because of poor seating of the fuel-pressure regulator Fuel pressure regulator
      Fuel pressure too high Sticking fuel pressure regulator Fuel pressure regulator
      Fuel pressure drops slowly after engine is stopped Injector leak Injector
      Fuel pressure drops immediately after engine is stopped The check valve within the fuel pump is open Fuel pump
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