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Home >> Hyundai >> 2017 >> Sonata Base >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 42 (Engine Control System Diagnosis - 2.0L (2 Of 3) (Except HEV)) >> DTC P0300: Random/Multiple Cylinder Misfire Detected >> System Inspection

System Inspection

WARNING: This page is about a different variant/trim than selected.

■ Visual Inspection 

  1. Visually/physically inspect for the following conditions
    • Vacuum hoses in engine room for splits, kinks and improper installation.
    • Positive crankcase ventilation valve for improper installation, damaged o-rings and malfunctioning.
    • Verify that the PCM ground connections are clean and properly tightened.
  2. Check MAFS and ECTS for the following conditions:
    • Contamination, deterioration, poor connection or damaged harness
    • The MAF signal displayed on the GDS should increase as engine speed increases
    • The engine coolant temperature displayed on the GDS should close to the actual coolant temperature
  3. Was a problem found in any of the above areas?

    YES 

    NO 

    • Go to next step below.

■ Timing Inspection 

  1. Set up an oscilloscope as follows:
    • Channel A (+): Signal terminal of the CMPS #1 (back probe), (-): ground
    • Channel B (+): Signal terminal of the CKPS (back probe), (-): ground
  2. Start the engine and check for signal waveform compared with reference waveform below.
    Fig 1: Scantool Display - Typical Crankshaft Position Sensor And Camshaft Position Sensor Waveform
    G11991731Courtesy of HYUNDAI MOTOR AMERICA
  3. Is the signal waveform normal?

    YES 

    • Go to next step below.

    NO 

    • Repair or readjust as necessary, if air gap of the CKPS is exceeds specification. If OK, check that the crankshaft and camshaft are correctly aligned the matching marks of the pulleys. Repair or readjust as necessary and go to "VERIFICATION OF VEHICLE REPAIR " procedure.

■ Spark Plug Cable & Ignition Coil Inspection 

  1. Visually/physically inspect the spark plug cable and ignition coil related to the misfiring cylinder(s) for the following conditions
    • Damage, cracks, carbon and flashover
    • Poor connection or damaged harness
    • Connected to the incorrect cylinders at the ignition coil and spark plug
  2. Measure the resistance of the spark plug cable related to the misfiring cylinder(s)

    Specification:  5.6 kΩ/m ± 20%

  3. Measure the resistance of the primary and secondary ignition coil related to the misfiring cylinder(s)

    Specification:  Primary Ignition Coil Resistance: 0.56~0.68 Ω at 20°C (68°F)

    Secondary Ignition Coil Resistance: 6~8 kΩ at 20°C (68°F)

  4. Was a problem found in any of the above areas?

    YES 

    NO 

    • Go to next step below.

■ Spark Plug Inspection 

  1. Visually/physically inspect the spark plug related to the misfiring cylinder(s) for the following conditions
    • Damaged insulation, Worn electrodes, Oil or fuel fouled, Loose terminals and cracks
    • Check for electrode 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
  2. Was a problem found in any of the above areas?

    YES 

    NO 

    • Go to next step below.

■ Fuel Line Pressure Inspection 

  1. Check the fuel for excessive water, alcohol, or other contaminants. Replace contaminated fuel as necessary.
  2. Install a fuel pressure gage.
  3. Inspect fuel pressure with normal idle status.

    Specification:  440 ~ 460 kPa (4.48 ~ 4.69 kg/cm2 , 63 ~ 66 psi)

  4. Is fuel pressure within the specified value?

    YES 

    • Go to next step below.

    NO 

Condition Possible Cause Suspected Area
Fuel Pressure too low Clogged fuel filter Fuel filter
Fuel leak on the fuel - pressure regulator that is assembled on fuel pump Fuel Pump (Fuel Pressure Regulator)
Fuel Pressure too High Sticking fuel pressure regulator Fuel Pump (Fuel Pressure Regulator)

■ Fuel Pressure Hold Inspection 

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

    Specification:  After engine stops, the gauge reading should hold for minimum 5 minutes

  2. Is fuel pressure within the specified value?

    YES 

    • Go to next step below.

    NO 

Condition Possible Cause Suspected Area
Fuel pressure drops slowly Injector leak Injector
Fuel pressure drops immediately Stuck open check valve of the fuel pump Fuel pump

■ Engine Compression Test 

  1. Warm up the engine to normal operating temperature. Verify the battery must be at or near full charge.
  2. With IG "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: 1,324 kPa (13.5 kgf/cm2 , 192 psi)/200 ~ 250 RPM

    Minimum pressure: 1,177 kPa (12.0 kgf/cm2 , 171 psi)

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