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 stores a DTC.

DTC No. DTC Detection Condition Trouble Area
P0300

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


  • A misfire occurs that may damage the three-way catalytic converter (MIL blinks when detect immediately).

  • An emission deterioration misfire occurs (MIL illuminates).

  • Open or short in engine wire harness

  • Connector connection

  • Vacuum hose connections

  • Ignition system

  • Fuel injector assembly

  • Fuel pressure

  • Mass air flow meter sub-assembly

  • 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 the following conditions is met (2 trip detection logic):


  • A misfire occurs that may damage the three-way catalytic converter (MIL blinks when detect immediately).

  • An 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.

MONITOR DESCRIPTION

The ECM illuminates the MIL and stores a DTC when either one of the following conditions, which could cause emission deterioration, is detected (2 trip detection logic).


The ECM flashes the MIL (immediate detection logic) and stores a DTC (2 trip detection logic) when either one of the following conditions, which could cause damage to the three-way catalytic converter, is detected.


MONITOR STRATEGY

Required Sensors/Components (Main)

Crankshaft position sensor

Camshaft position sensor
Required Sensors/Components (Related)

Engine coolant temperature

Intake air temperature sensor

Mass air flow meter sub-assembly
Frequency of Operation Continuous

TYPICAL ENABLING CONDITIONS

Misfire
Intake air temperature Higher than -10°C (14°F)
Either of the following conditions is met (a) or (b)
(a) Engine coolant temperature at engine start Higher than -7°C (19°F)
(b) Engine coolant temperature Higher than 20°C (68°F)
Monitor Period of Emission-related Misfire
Duration 1000 crankshaft revolutions x 4
Monitor Period of Catalyst-damaging Misfire (MIL Blinks)
Duration 200 crankshaft revolutions x 3

CONFIRMATION DRIVING PATTERN


  1. Connect the intelligent tester to the DLC3.

  2. Turn the ignition switch to ON.

  3. Turn the tester on.

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

  5. Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure).

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

  7. 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.

  8. Drive the vehicle so that the vehicle conditions displayed in Misfire RPM and Misfire Load of the Data List are the same as the freeze frame data. Perform this step several times.

    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 8.0 minutes or more
    1000 4.5 minutes or more
    2000 2.5 minutes or more
    3000 1.5 minutes or more

  9. Check whether misfires have occurred by checking DTCs and freeze frame data.

    Tech Tips

    Do not turn the ignition 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.

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

  11. Turn the ignition switch off and wait for at least 30 seconds.

  12. Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure).

WIRING DIAGRAM

Refer to DTC P0102 Click here.

Refer to Fuel Injector Circuit Click here.

INSPECTION PROCEDURE

Note

Inspect the fuses for circuits related to this system before performing the following 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 was 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 +/-15%, the air fuel ratio may be rich (-15% or less) or lean (15% or higher).

  • 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 to be stored.

PROCEDURE


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


    1. Connect the intelligent tester to the DLC3.

    2. Turn the ignition switch to ON.

    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

    GO TO DTC CHART Click here

    A

  2. CHECK PCV HOSE CONNECTIONS


    1. Check the PCV hose connections Click here.

      OK
      PCV valve and hose are correctly connected and are not damaged.

    NG

    REPAIR OR REPLACE PCV HOSE

    OK

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


    1. Connect the intelligent tester to the DLC3.

    2. Turn the ignition switch to ON.

    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 MISFIRE COUNT)


    1. Connect the intelligent tester to the DLC3.

    2. Turn the ignition switch to ON.

    3. Turn the tester on.

    4. Enter the following menus: Powertrain / Engine and ECT / Data List / All Data / Cylinder #1 Misfire Count, Cylinder #2 Misfire Count, Cylinder #3 Misfire Count and Cylinder #4 Misfire Count.

    5. Start the engine and allow the engine to idle.

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

    7. 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].

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

      Result
      Result 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

    CHECK INTAKE SYSTEM Click here

    A

  5. INSPECT SPARK PLUG


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


    NG

    REPLACE SPARK PLUG Click here

    OK

  6. CHECK FOR SPARK (SPARK TEST)


    1. Perform a spark test Click here.

      Tech Tips

      If the result of the spark test is normal, proceed to the next step.


    NEXT

  7. CHECK CYLINDER COMPRESSION PRESSURE


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


    NG

    CHECK ENGINE TO DETERMINE CAUSE OF LOW COMPRESSION

    OK

  8. CHECK TERMINAL VOLTAGE (#10, #20, #30 AND/OR #40)


    1. A01EYUKE77
      Text in Illustration
      *a

      Front view of wire harness connector

      (to ECM)

      Disconnect the ECM connector.

    2. Turn the ignition switch to ON.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      E83-108 (#10) - E83-45 (E01) Ignition switch ON 11 to 14 V
      E83-107 (#20) - E83-45 (E01) Ignition switch ON 11 to 14 V
      E83-106 (#30) - E83-45 (E01) Ignition switch ON 11 to 14 V
      E83-105 (#40) - E83-45 (E01) Ignition switch ON 11 to 14 V

    NG

    GO TO FUEL INJECTOR CIRCUIT Click here

    OK

  9. CHECK FUEL INJECTOR OF MISFIRING CYLINDER


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


    NG

    REPLACE FUEL INJECTOR ASSEMBLY Click here

    OK

  10. CHECK VALVE CLEARANCE OF MISFIRING CYLINDER


    1. Check the valve clearance Click here.


    NG

    ADJUST VALVE CLEARANCE Click here

    OK

  11. CHECK INTAKE SYSTEM


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

      OK
      No leaks from intake system.

    NG

    REPAIR OR REPLACE INTAKE SYSTEM

    OK

  12. CHECK FUEL PRESSURE


    1. Check the fuel pressure Click here.


    NG

    CHECK FUEL LINE Click here

    OK

  13. READ VALUE USING INTELLIGENT TESTER (COOLANT TEMP)


    1. Connect the intelligent tester to the DLC3.

    2. Turn the ignition switch to ON.

    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 75 and 100°C (167 and 212°F)

    NG

    REPLACE ENGINE COOLANT TEMPERATURE SENSOR Click here

    OK

  14. READ VALUE USING INTELLIGENT TESTER (MAF)


    1. Connect the intelligent tester to the DLC3.

    2. Turn the ignition switch to ON.

    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 8 gm/sec and 22 gm/sec

    NG

    CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER SUB-ASSEMBLY CONNECTOR CONNECTION) Click here

    OK

  15. CHECK VALVE TIMING (CHECK FOR LOOSE TIMING CHAIN AND JUMPED TEETH)

    A01EVKIE03
    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.

    OK

    CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER SUB-ASSEMBLY CONNECTOR CONNECTION) Click here

    NG

    ADJUST VALVE TIMING Click here

  16. CHECK INTAKE SYSTEM


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

      OK
      No leaks from intake system.

    NG

    REPAIR OR REPLACE INTAKE SYSTEM

    OK

  17. CHECK FUEL PRESSURE


    1. Check the fuel pressure Click here.


    NG

    CHECK FUEL LINE Click here

    OK

  18. READ VALUE USING INTELLIGENT TESTER (COOLANT TEMP)


    1. Connect the intelligent tester to the DLC3.

    2. Turn the ignition switch to ON.

    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 75 and 100°C (167 and 212°F)

    NG

    REPLACE ENGINE COOLANT TEMPERATURE SENSOR Click here

    OK

  19. READ VALUE USING INTELLIGENT TESTER (MAF)


    1. Connect the intelligent tester to the DLC3.

    2. Turn the ignition switch to ON.

    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 8 gm/sec and 22 gm/sec

    NG

    CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER SUB-ASSEMBLY CONNECTOR CONNECTION) Click here

    OK

  20. CHECK VALVE TIMING (CHECK FOR LOOSE TIMING CHAIN AND JUMPED TEETH)

    A01EVKIE03
    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

    ADJUST VALVE TIMING Click here

    OK

  21. INSPECT SPARK PLUG


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


    NG

    REPLACE SPARK PLUG Click here

    OK

  22. CHECK FOR SPARK (SPARK TEST)


    1. Perform a spark test Click here.

      Tech Tips

      If the result of the spark test is normal, proceed to the next step.


    NEXT

  23. CHECK CYLINDER COMPRESSION PRESSURE


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


    NG

    CHECK ENGINE TO DETERMINE CAUSE OF LOW COMPRESSION

    OK

  24. CHECK TERMINAL VOLTAGE (#10, #20, #30 AND/OR #40)


    1. A01EYUKE77
      Text in Illustration
      *a

      Front view of wire harness connector

      (to ECM)

      Disconnect the ECM connector.

    2. Turn the ignition switch to ON.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      E83-108 (#10) - E83-45 (E01) Ignition switch ON 11 to 14 V
      E83-107 (#20) - E83-45 (E01) Ignition switch ON 11 to 14 V
      E83-106 (#30) - E83-45 (E01) Ignition switch ON 11 to 14 V
      E83-105 (#40) - E83-45 (E01) Ignition switch ON 11 to 14 V

    NG

    GO TO FUEL INJECTOR CIRCUIT Click here

    OK

  25. CHECK FUEL INJECTOR OF MISFIRING CYLINDER


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


    NG

    REPLACE FUEL INJECTOR ASSEMBLY Click here

    OK

  26. CHECK VALVE CLEARANCE OF MISFIRING CYLINDER


    1. Check the valve clearance Click here.


    NG

    ADJUST VALVE CLEARANCE Click here

    OK

  27. CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER SUB-ASSEMBLY CONNECTOR CONNECTION)


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

      Tech Tips

      Repair any problems.


    NEXT

  28. CHECK WHETHER DTC OUTPUT RECURS (MISFIRE DTCS)


    1. Connect the intelligent tester to the DLC3.

    2. Turn the ignition switch to ON.

    3. Turn the tester on.

    4. Clear the DTCs Click here.

    5. Turn the ignition switch off and wait for at least 30 seconds.

    6. Turn the ignition switch to ON.

    7. Turn the tester on.

    8. Start the engine and warm it up.

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

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

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

    12. 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

    END

    A

  29. 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
      Tester Connection Condition Specified Condition
      E14-5 (VG) - E83-118 (VG) Always Below 1 Ω
      E14-4 (E2G) - E83-116 (E2G) Always Below 1 Ω
      E14-5 (VG) or E83-118 (VG) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  30. REPLACE MASS AIR FLOW METER SUB-ASSEMBLY


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

      Tech Tips

      If the results of the inspections performed in steps 14 and 19 indicated no problem, proceed to the next step without replacing the mass air flow meter sub-assembly.


    NEXT

  31. CONFIRM WHETHER MALFUNCTION HAS BEEN SUCCESSFULLY REPAIRED


    1. Connect the intelligent tester to the DLC3.

    2. Turn the ignition switch to ON.

    3. Turn the tester on.

    4. Clear the DTCs Click here.

    5. Turn the ignition switch off and wait for at least 30 seconds.

    6. Turn the ignition switch to ON.

    7. Turn the tester on.

    8. Start the engine and warm it up.

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

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

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

    12. 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

    REPLACE ECM Click here

    A

    END

  32. CHECK FUEL LINE


    1. Check the fuel lines for leaks or blockage.


    NG

    REPAIR OR REPLACE FUEL LINE

    OK

    REPLACE FUEL PUMP Click here