SFI SYSTEM, Diagnostic DTC:P0300, P0301, P0302, P0303, P0304

DTC Code DTC Name
P0300 Random / Multiple Cylinder Misfire Detected
P0301 Cylinder 1 Misfire Detected
P0302 Cylinder 2 Misfire Detected
P0303 Cylinder 3 Misfire Detected
P0304 Cylinder 4 Misfire Detected

DESCRIPTION

When the engine misfires, high concentrations of hydrocarbons (HC) enter the exhaust gas. Extremely high hydrocarbon concentration levels can cause an increase in exhaust emission levels. Extremely high concentrations of hydrocarbons can also cause increases in the three-way catalytic converter temperature, which may cause damage to the three-way catalytic converter. To prevent this increase in emissions and to limit the possibility of thermal damage, the ECM monitors the misfire count. When the temperature of the three-way catalytic converter reaches the point of thermal degradation, the ECM blinks the MIL. To monitor misfires, the ECM uses both the camshaft position sensor and the crankshaft position sensor. The camshaft position sensor is used to identify any misfiring cylinders and the crankshaft position sensor is used to measure variations in the crankshaft rotation speed. Misfires are counted when the crankshaft rotation speed variations exceed predetermined thresholds. If the misfire count exceeds the threshold levels, and could cause emission control system performance deterioration, the ECM illuminates the MIL and sets a DTC.

DTC No. DTC Detection Condition Trouble Area
P0300

Simultaneous misfiring of several cylinders occurs and one of following conditions below is detected (2 trip detection logic):


  • High temperature misfire occurs in three-way catalytic converter (MIL blinks)

  • Emission deterioration misfire occurs (MIL illuminates)


  • Open or short in engine wire harness

  • Connector connections

  • Vacuum hose connections

  • Ignition system

  • Fuel injector assembly

  • Fuel pressure

  • Fuel line

  • Fuel pump assembly

  • Mass air flow meter

  • Engine coolant temperature sensor

  • Compression pressure

  • Valve clearance

  • Valve timing

  • PCV valve and hose

  • PCV hose connections

  • Intake system

  • ECM

P0301

P0302

P0303

P0304

Misfiring of a specific cylinder occurs and one of following conditions below is detected (2 trip detection logic):


  • High temperature misfire occurs in three-way catalytic converter (MIL blinks)

  • Emission deterioration misfire occurs (MIL illuminates)

When DTCs for misfiring cylinders are randomly stored, but DTC P0300 is not stored, it indicates that misfires have been detected in different cylinders at different times. DTC P0300 is only stored when several misfiring cylinders are detected at the same time.

CONFIRMATION DRIVING PATTERN


  1. Connect the intelligent tester to the DLC3.

  2. Turn the engine switch on (IG).

  3. Turn the tester on.

  4. Record the DTC(s) and freeze frame data.

  5. Using the tester, switch the ECM from normal mode to check mode Click here.

  6. Read the misfire counts of each cylinder, Cylinder #1 Misfire Count to Cylinder #4 Misfire Count, with the engine idling. If any misfire count is displayed, skip the following confirmation driving pattern.

  7. Drive the vehicle several times with the conditions, such as engine speed and engine load, shown in Misfire RPM and Misfire Load in the Data List.

    Tech Tips

    In order to store misfire DTCs, it is necessary to operate the vehicle for the period of time shown in the table below. Confirm the Misfire RPM and Misfire Load in the Data List.

    Engine Speed Duration
    Idling 8 minutes and 30 seconds or more
    1000 4 minutes 30 seconds or more
    1500 3 minutes or more
    2500 2 minutes or more
  8. Check whether misfires have occurred by checking DTCs and freeze frame data.

    Tech Tips

    Do not turn the engine switch off until the output DTC(s) and freeze frame data have been recorded. When the ECM returns to normal mode (default), the stored DTC(s), freeze frame data and other data are cleared.

  9. Record the DTC(s), freeze frame data and misfire counts.

  10. Turn the engine switch off and wait for at least 5 seconds.

WIRING DIAGRAM

Refer to DTC P0100 Click here.

Refer to Fuel Injector Circuit Click here.

INSPECTION PROCEDURE

Tech Tips


  • If any DTCs other than misfire DTCs are output, troubleshoot those DTCs first.

  • Read freeze frame data using the intelligent tester. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, if the air fuel ratio was lean or rich, and other data from the time the malfunction occurred.

  • If the misfire does not recur when the vehicle is brought to the workshop, reproduce the conditions stored in the ECM as freeze frame data.

  • If the misfire still cannot be reproduced even though the conditions stored in the ECM as freeze frame data have been reproduced, one of the following factors is considered to be a possible cause of the problem:


    1. There was insufficient fuel in the tank.

    2. Improper fuel is used.

    3. The spark plugs have been contaminated.

    4. The problem requires further diagnosis.

  • After finishing repairs, check the misfire counts of the cylinders (Cylinder #1 Misfire Count to Cylinder #4 Misfire Count).

  • Be sure to confirm that no misfiring cylinder DTCs are stored again by conducting the confirmation driving pattern after finishing repairs.

  • When one of Short FT #1 or Long FT #1 in the freeze frame data is outside the range of +/-20%, the air fuel ratio may be rich (-20% or less) or lean (+20% or more).

  • When Coolant Temp in the freeze frame data is below 75°C (167°F), the misfires have occurred only while warming up the engine.

  • An extremely imbalanced drive wheel which causes body vibration may cause misfire DTCs detection.

PROCEDURE


  1. CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO MISFIRE DTCS)


    1. Connect the intelligent tester to the DLC3.

    2. Turn the engine switch on (IG).

    3. Turn the tester on.

    4. Enter the following menus: Powertrain / Engine and ECT / DTC.

    5. Read the DTCs.

      Result
      Result Proceed to
      DTC P0300, P0301, P0302, P0303 and/or P0304 are output A
      DTC P0300, P0301, P0302, P0303 and/or P0304 and other DTCs are output B

      Tech Tips

      If any DTCs other than P0300, P0301, P0302, P0303 and P0304 are output, troubleshoot those DTCs first.


    B
    A
  2. CHECK PCV HOSE CONNECTIONS


    1. Check the PCV hose connections Click here.

      OK
      PCV hose is correctly connected and is not damaged.

    NG
    OK
  3. READ VALUE USING INTELLIGENT TESTER (MISFIRE RPM AND MISFIRE LOAD)


    1. Connect the intelligent tester to the DLC3.

    2. Turn the engine switch on (IG).

    3. Turn the tester on.

    4. Enter the following menus: Powertrain / Engine and ECT / Data List / All Data / Misfire RPM and Misfire Load.

    5. Read and note the Misfire RPM and Misfire Load values.

      Tech Tips

      The Misfire RPM and Misfire Load values indicate the vehicle conditions under which the misfire occurred.


    NEXT
  4. READ VALUE USING INTELLIGENT TESTER (CYLINDER #1, #2, #3 AND #4 MISFIRE COUNT)


    1. Connect the intelligent tester to the DLC3.

    2. Turn the engine switch on (IG).

    3. Turn the tester on.

    4. Enter the following menus: Powertrain / Engine and ECT / Data List / All Data / Cylinder #1 (to #4) Misfire Count.

    5. Read each value for Cylinder #1 (to #4) Misfire Count displayed on the tester. If no misfire counts occur in any cylinders, perform steps [A] and [B] and then check the misfire counts again.

    6. Drive the vehicle with the Misfire RPM and Misfire Load noted in the "READ VALUE USING INTELLIGENT TESTER (MISFIRE RPM AND MISFIRE LOAD)" procedures above [A].

    7. Read the Cylinder #1 (to #4) Misfire Count or DTCs displayed on the tester [B].

      Result

      Result

      (Misfire Count)

      Proceed to
      Most misfires occur in only 1 or 2 cylinders A
      3 cylinders or more have equal misfire counts B

      Tech Tips


      • If it is difficult to reproduce misfires for each cylinder, check the Data List item called Misfire Margin. Try to find vehicle driving conditions that lower the Misfire Margin value. Values above 30% are considered normal.

      • If the freeze frame data record of the engine coolant temperature is below 75°C (167°F), the misfire may be detected only when the engine is cold.

      • If the freeze frame data record of the Engine Run Time is below 120 seconds, the misfire may be detected immediately after the engine is started.


    B
    A
  5. INSPECT SPARK PLUG


    1. Inspect the spark plug of the misfiring cylinder Click here.


    NG
    OK
  6. CHECK FOR SPARK (SPARK TEST)


    1. Perform a spark test Click here.

      CAUTION:

      Always disconnect all injector connectors.

      Note

      Do not crank the engine for more than 2 seconds.

      OK
      Spark jumps across electrode gap.

    NG
    OK
  7. CHECK CYLINDER COMPRESSION PRESSURE OF MISFIRING CYLINDER


    1. Measure the cylinder compression pressure of the misfiring cylinder Click here.


    NG
    OK
  8. CHECK FUEL INJECTOR ASSEMBLY (POWER SOURCE)


    1. A01CBQLE28
      Text in Illustration
      *1

      Front view of wire harness connector

      (to Fuel Injector Assembly)

      Disconnect the fuel injector assembly connectors.

    2. Turn the engine switch on (IG).

    3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage
      Tester Connection Condition Specified Condition
      D56-1 - Body ground Engine switch on (IG) 11 to 14 V
      D45-1 - Body ground Engine switch on (IG) 11 to 14 V
      D55-1 - Body ground Engine switch on (IG) 11 to 14 V
      D44-1 - Body ground Engine switch on (IG) 11 to 14 V
    4. Turn the engine switch off.

    5. Reconnect the fuel injector assembly connectors.


    NG
    OK
  9. CHECK HARNESS AND CONNECTOR (FUEL INJECTOR ASSEMBLY - ECM)


    1. Disconnect the fuel injector assembly connectors.

    2. Disconnect the ECM connector.

    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance (Check for Open)
      Tester Connection Condition Specified Condition
      D56-2 - D41-108 (#10) Always Below 1 Ω
      D45-2 - D41-107 (#20) Always Below 1 Ω
      D55-2 - D41-106 (#30) Always Below 1 Ω
      D44-2 - D41-105 (#40) Always Below 1 Ω
      Standard Resistance (Check for Short)
      Tester Connection Condition Specified Condition
      D56-2 or D41-108 (#10) - Body ground Always 10 kΩ or higher
      D45-2 or D41-107 (#20) - Body ground Always 10 kΩ or higher
      D55-2 or D41-106 (#30) - Body ground Always 10 kΩ or higher
      D44-2 or D41-105 (#40) - Body ground Always 10 kΩ or higher
    4. Reconnect the fuel injector assembly connectors.

    5. Reconnect the ECM connector.


    NG
    OK
  10. INSPECT FUEL INJECTOR ASSEMBLY OF MISFIRING CYLINDER


    1. Inspect the fuel injector assembly injection (whether fuel volume is high or low, and whether injection pattern is poor) Click here.


    NG
    OK
  11. CHECK INTAKE SYSTEM


    1. Check the intake system for vacuum leaks Click here.

      OK
      No leaks in the intake system.

    NG
    OK
  12. CHECK FUEL PRESSURE


    1. Check the fuel pressure Click here.


    NG
    OK
  13. READ VALUE USING INTELLIGENT TESTER (COOLANT TEMP)


    1. Connect the intelligent tester to the DLC3.

    2. Turn the engine switch on (IG).

    3. Turn the tester on.

    4. Enter the following menus: Powertrain / Engine and ECT / Data List / All Data / Coolant Temp.

    5. Read the Data List twice, when the engine is both cold and warmed up.

      Standard
      Tester Display Condition Specified Condition
      Coolant Temp Cold engine Same as ambient air temperature
      Warm engine Between 80 and 105°C (176 and 221°F)

    NG
    OK
  14. READ VALUE USING INTELLIGENT TESTER (MAF)


    1. Connect the intelligent tester to the DLC3.

    2. Turn the engine switch on (IG).

    3. Turn the tester on.

    4. Enter the following menus: Powertrain / Engine and ECT / Data List / All Data / MAF, Coolant Temp and Engine Speed.

    5. Allow the engine to idle until Coolant Temp reaches 75°C (167°F) or higher.

    6. Read MAF with the engine speed at 3000 rpm.

      Standard
      Tester Display Condition Specified Condition
      MAF

      Shift lever position: N

      A/C: Off

      Engine Speed: 3000 rpm

      Between 9.8 gm/sec and 13.5 gm/sec

    NG
    OK
  15. CHECK VALVE TIMING

    A01CAMGE03
    Text in Illustration
    *1 Timing Mark
    *2 Front Mark
    *3 Groove

    1. Remove the cylinder head cover sub-assembly.

    2. Turn the crankshaft pulley, and align its groove with the "0" timing mark of the timing chain cover.

    3. Check that the timing marks of the camshaft timing gear assembly and camshaft timing sprocket are aligned with the front marks located on the No. 1 and No. 2 bearing caps as shown in the illustration.

      Tech Tips

      If the timing marks are not as shown, turn the crankshaft one revolution clockwise.

      OK
      Timing marks on camshaft timing gear assembly and camshaft timing sprocket are aligned as shown in the illustration.

    NG
    OK
  16. CHECK VALVE CLEARANCE OF MISFIRING CYLINDER


    1. Check the valve clearance Click here.


    OK
    NG
  17. CHECK INTAKE SYSTEM


    1. Check the intake system for vacuum leaks Click here.

      OK
      No leaks in the intake system.

    NG
    OK
  18. CHECK FUEL PRESSURE


    1. Check the fuel pressure Click here.


    NG
    OK
  19. READ VALUE USING INTELLIGENT TESTER (COOLANT TEMP)


    1. Connect the intelligent tester to the DLC3.

    2. Turn the engine switch on (IG).

    3. Turn the tester on.

    4. Enter the following menus: Powertrain / Engine and ECT / Data List / All Data / Coolant Temp.

    5. Read the Data List twice, when the engine is both cold and warmed up.

      Standard
      Tester Display Condition Specified Condition
      Coolant Temp Cold engine Same as ambient air temperature
      Warm engine Between 80 and 105°C (176 and 221°F)

    NG
    OK
  20. READ VALUE USING INTELLIGENT TESTER (MAF)


    1. Connect the intelligent tester to the DLC3.

    2. Turn the engine switch on (IG).

    3. Turn the tester on.

    4. Enter the following menus: Powertrain / Engine and ECT / Data List / All Data / MAF, Coolant Temp and Engine Speed.

    5. Allow the engine to idle until Coolant Temp reaches 75°C (167°F) or higher.

    6. Read MAF with the engine speed at 3000 rpm.

      Standard
      Tester Display Condition Specified Condition
      MAF

      Shift lever position: N

      A/C: Off

      Engine Speed: 3000 rpm

      Between 9.8 gm/sec and 13.5 gm/sec

    NG
    OK
  21. CHECK VALVE TIMING

    A01CAMGE03
    Text in Illustration
    *1 Timing Mark
    *2 Front Mark
    *3 Groove

    1. Remove the cylinder head cover sub-assembly.

    2. Turn the crankshaft pulley, and align its groove with the "0" timing mark of the timing chain cover.

    3. Check that the timing marks of the camshaft timing gear assembly and camshaft timing sprocket are aligned with the front marks located on the No. 1 and No. 2 bearing caps as shown in the illustration.

      Tech Tips

      If the timing marks are not as shown, turn the crankshaft one revolution clockwise.

      OK
      Timing marks on camshaft timing gear assembly and camshaft timing sprocket are aligned as shown in the illustration.

    NG
    OK
  22. INSPECT SPARK PLUG


    1. Inspect the spark plug of the misfiring cylinder Click here.


    NG
    OK
  23. CHECK FOR SPARK (SPARK TEST)


    1. Perform a spark test Click here.

      CAUTION:

      Always disconnect all injector connectors.

      Note

      Do not crank the engine for more than 2 seconds.

      OK
      Spark jumps across electrode gap.

    NG
    OK
  24. CHECK CYLINDER COMPRESSION PRESSURE


    1. Measure the cylinder compression pressure of the misfiring cylinder Click here.


    NG
    OK
  25. CHECK FUEL INJECTOR ASSEMBLY (POWER SOURCE)


    1. A01CBQLE28
      Text in Illustration
      *1

      Front view of wire harness connector

      (to Fuel Injector Assembly)

      Disconnect the fuel injector assembly connectors.

    2. Turn the engine switch on (IG).

    3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage
      Tester Connection Condition Specified Condition
      D56-1 - Body ground Engine switch on (IG) 11 to 14 V
      D45-1 - Body ground Engine switch on (IG) 11 to 14 V
      D55-1 - Body ground Engine switch on (IG) 11 to 14 V
      D44-1 - Body ground Engine switch on (IG) 11 to 14 V
    4. Turn the engine switch off.

    5. Reconnect the fuel injector assembly connectors.


    NG
    OK
  26. CHECK HARNESS AND CONNECTOR (FUEL INJECTOR ASSEMBLY - ECM)


    1. Disconnect the fuel injector assembly connectors.

    2. Disconnect the ECM connector.

    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance (Check for Open)
      Tester Connection Condition Specified Condition
      D56-2 - D41-108 (#10) Always Below 1 Ω
      D45-2 - D41-107 (#20) Always Below 1 Ω
      D55-2 - D41-106 (#30) Always Below 1 Ω
      D44-2 - D41-105 (#40) Always Below 1 Ω
      Standard Resistance (Check for Short)
      Tester Connection Condition Specified Condition
      D56-2 or D41-108 (#10) - Body ground Always 10 kΩ or higher
      D45-2 or D41-107 (#20) - Body ground Always 10 kΩ or higher
      D55-2 or D41-106 (#30) - Body ground Always 10 kΩ or higher
      D44-2 or D41-105 (#40) - Body ground Always 10 kΩ or higher
    4. Reconnect the fuel injector assembly connectors.

    5. Reconnect the ECM connector.


    NG
    OK
  27. INSPECT FUEL INJECTOR ASSEMBLY OF MISFIRING CYLINDER


    1. Inspect the fuel injector assembly injection (whether fuel volume is high or low, and whether injection pattern is poor) Click here.


    NG
    OK
  28. CHECK VALVE CLEARANCE OF MISFIRING CYLINDER


    1. Check the valve clearance Click here.


    NG
    OK
  29. CHECK HARNESS AND CONNECTOR


    1. Check the connection and terminal contact pressure of connectors and wire harness between the mass air flow meter sub-assembly and ECM Click here.

      Tech Tips

      Repair any problems.


    NEXT
  30. PERFORM CONFIRMATION DRIVING PATTERN


    1. Connect the intelligent tester to the DLC3.

    2. Turn the engine switch on (IG).

    3. Turn the tester on.

    4. Clear the DTCs Click here.

    5. Drive the vehicle in accordance with the driving pattern described in the Confirmation Driving Pattern.


    NEXT
  31. CHECK WHETHER DTC OUTPUT RECURS (DTC P0300, P0301, P0302, P0303, P0304)


    1. Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.

    2. Input the DTC: P0300, P0301, P0302, P0303 or P0304.

    3. Check the DTC judgment result.

      Result
      Result Proceed to

      ABNORMAL

      (DTC P0300, P0301, P0302, P0303 or P0304 is output)

      A

      NORMAL

      (DTC is not output)

      B

    B
    A
  32. CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER SUB-ASSEMBLY - ECM)


    1. Disconnect the mass air flow meter sub-assembly connector.

    2. Disconnect the ECM connector.

    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance (Check for Open)
      Tester Connection Condition Specified Condition
      D2-5 (VG) - D41-118 (VG) Always Below 1 Ω
      D2-4 (E2G) - D41-116 (E2G) Always Below 1 Ω
      Standard Resistance (Check for Short)
      Tester Connection Condition Specified Condition
      D2-5 (VG) or D41-118 (VG) - Body ground Always 10 kΩ or higher
    4. Reconnect the ECM connector.

    5. Reconnect the mass air flow meter sub-assembly connector.


    NG
    OK
  33. REPLACE MASS AIR FLOW METER SUB-ASSEMBLY


    1. Replace the mass air flow meter sub-assembly Click here.

      Tech Tips

      If the result of the inspection performed in steps 14 and 20 indicated no problem, proceed to the next step without replacing the mass air flow meter.


    NEXT
  34. PERFORM CONFIRMATION DRIVING PATTERN


    1. Connect the intelligent tester to the DLC3.

    2. Turn the engine switch on (IG).

    3. Turn the tester on.

    4. Clear the DTCs Click here.

    5. Drive the vehicle in accordance with the driving pattern described in the Confirmation Driving Pattern.


    NEXT
  35. CONFIRM WHETHER MALFUNCTION HAS BEEN SUCCESSFULLY REPAIRED


    1. Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.

    2. Input the DTC: P0300, P0301, P0302, P0303 or P0304.

    3. Check the DTC judgment result.

      Result
      Result Proceed to

      NORMAL

      (DTC is not output)

      A

      ABNORMAL

      (DTC P0300, P0301, P0302, P0303 or P0304 is output)

      B

    B
    A
  36. CHANGE TO NORMAL SPARK PLUG AND CHECK SPARK OF MISFIRING CYLINDER


    1. Change the installed spark plug to a known good spark plug.

    2. Perform a spark test Click here.

      CAUTION:

      Always disconnect all injector connectors.

      Note

      Do not crank the engine for more than 2 seconds.

      OK
      Spark jumps across electrode gap.

    NG
    OK
  37. CHANGE TO NORMAL IGNITION COIL ASSEMBLY AND CHECK SPARK OF MISFIRING CYLINDER


    1. Change the installed ignition coil assembly to a known good ignition coil assembly.

    2. Perform a spark test Click here.

      CAUTION:

      Always disconnect all injector connectors.

      Note

      Do not crank the engine for more than 2 seconds.

      OK
      Spark jumps across electrode gap.

    NG
    OK
  38. CHECK FUEL LINE


    1. Check the fuel lines for leaks or blockage.


    NG
    OK