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

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

DESCRIPTION

When a misfire occurs in the engine, hydrocarbons (HC) enter the exhaust gas in high concentrations. If this HC concentration is high enough, there could be an increase in exhaust emission levels. High concentrations of HC can also cause the temperature of the Three-Way Catalytic Converter (TWC) to increase, possibly damaging the TWC. To prevent this increase in emissions and limit the possibility of thermal damage, the ECM monitors the misfire rate. When the temperature of the TWC 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 misfiring cylinders and the crankshaft position sensor is used to measure variations in the crankshaft rotation speed. The misfire counter increments when the crankshaft rotation speed variations exceed the threshold values.

If the misfiring rate exceeds the threshold and could cause emission deterioration, the ECM illuminates the MIL.

Tech Tips


  • The ECM monitors misfires, which could cause emission deterioration, every 1000 crankshaft revolutions. When these misfires are detected, the ECM illuminates the MIL and stores a DTC.

  • The ECM monitors misfires, which could damage the TWC, every 200 crankshaft revolutions. When these misfires are detected, the ECM flashes the MIL and stores a DTC.

DTC No. DTC Detection Condition Trouble Area
P0300

Misfiring of random cylinders is detected

(2 trip detection logic)

  • Open or short in engine wire harness

  • Connector connection

  • Ignition system

  • Fuel injector assembly

  • Fuel pressure

  • Manifold absolute pressure sensor

  • Engine coolant temperature sensor

  • Compression pressure

  • Valve clearance

  • Valve timing

  • ECM

P0301

P0302

P0303

Misfiring of each cylinder is detected

(2 trip detection logic)

  • Open or short in engine wire harness

  • Connector connection

  • Ignition system

  • Fuel injector assembly

  • Fuel pressure

  • Manifold absolute pressure sensor

  • Engine coolant temperature sensor

  • Compression pressure

  • Valve clearance

  • Valve timing

  • ECM

Tech Tips

These DTCs are detected when the engine idles for approximately 10 minutes after warm-up. (Misfire can be clearly checked by activating the air conditioning system.)

WIRING DIAGRAM

A01VKKXE01

CONFIRMATION DRIVING PATTERN


  1. Connect an intelligent tester to the DLC3.

  2. Turn the ignition switch to ON.

  3. Turn the tester on.

  4. Record DTCs and freeze frame data.

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

  6. Read the misfire counts of each cylinder (Cylinder #1, #2, and #3) with the engine in an idling condition. If any misfire count is displayed, skip the following confirmation driving pattern.

  7. Drive the vehicle several times with the conditions, such as engine rpm and engine load, shown in Misfire RPM in the freeze frame data.

    Tech Tips

    In order to store misfire DTCs, it is necessary to drive the vehicle for the period of time shown in the table below, with the engine speed and engine load the same as Misfire RPM in the freeze frame data.

    Engine RPM Duration
    Idling 10 minutes or more
    1000 4 minutes 30 seconds or more
    2000 2 minute 30 seconds or more
    3000 1 minute 30 seconds or more

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

    Tech Tips

    Do not turn the ignition switch off until the stored DTC(s) and freeze frame data have been recorded.

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

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

  11. Clear DTCs (even if no DTCs are stored, perform the clear DTC operation).

CAUTION / NOTICE / HINT

Note


  • Perform electronic throttle learning after replacing the ECM Click here.

  • 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. Freeze frame data records the engine condition when malfunctions are detected. 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 freeze frame data.

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


    1. The fuel level is low.

    2. Improper fuel is used.

    3. The spark plugs are dirty.

    4. The problem is complex and involves multiple factors.

  • After finishing repairs, check that no misfire occurs in each cylinder (Cylinder No. 1, No. 2 and No. 3).

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

  • When either Short FT #1 or Long FT #1 in the freeze frame data is outside the range of +/-25%, the air fuel ratio may be rich (-25% or less) or lean (+25% or more).

  • When the Coolant Temp in the freeze frame data is less than 75°C (167°F), the misfires 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 DTC OUTPUT (IN ADDITION TO P0300, P0301, P0302 OR P0303)


    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 DTC.

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

      Tech Tips

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


    B

    GO TO DTC CHART Click here

    A

  2. READ VALUE USING INTELLIGENT TESTER (CYLINDER MISFIRE RPM)


    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 / Misfire RPM.

    5. Read and note the Misfire RPM value.

      Tech Tips

      The Misfire RPM value indicate the vehicle conditions under which the misfire occurred.


    NEXT

  3. CHECK PCV HOSE (HOSE CONNECTIONS)


    1. Check the PCV hose connections Click here.

      OK
      PCV hose is connected correctly and is not damaged.

    NG

    REPAIR OR REPLACE PCV HOSE Click here

    OK

  4. READ VALUE USING INTELLIGENT TESTER (MISFIRE COUNT)


    1. Connect the intelligent tester to the DLC3.

    2. Turn the ignition switch to ON.

    3. Turn the tester on.

    4. Clear DTCs Click here.

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

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

    7. Read each value for Cylinder #1 (to #3) Misfire Count displayed on the tester. If no misfire counts occur in any cylinders, perform the following procedure:


      1. Check the Cylinder #1 (to #3) Misfire Count.

      2. If misfire counts are still not displayed, perform procedure "A" and "B", and then check the misfire counts again.

        Procedure A: Drive the vehicle with the Misfire RPM noted in the read value using the intelligent tester (Misfire RPM) procedures above.

        Procedure B: Read Cylinder #1 (to #3) Misfire Count or the DTCs displayed on the tester.

        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 the Coolant Temp value of the freeze frame data is below 75°C (167°F), the misfire may be detected only when the engine is cold.

        • Engine Run Time value of the freeze frame data 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 SPARKS AND IGNITION


    1. Perform a spark test Click here.

      CAUTION:

      During the test, disconnect all of the fuel injector assembly connectors.

      Note

      Do not crank the engine for more than 2 seconds.


    NG

    CHANGE TO NORMAL SPARK PLUG AND CHECK SPARK OF MISFIRING CYLINDER Click here

    OK

  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 ECM TERMINAL VOLTAGE (#10, #20, AND/OR #30)

    A01VL02E01
    Text in Illustration
    *a

    Front view of wire harness connector

    (to ECM)

    1. 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 Switch Condition Specified Condition
      B87-45 (#10) - A71-21 (E01) Ignition switch ON 11 to 14 V
      B87-46 (#20) - A71-21 (E01) Ignition switch ON 11 to 14 V
      B87-67 (#30) - A71-21 (E01) Ignition switch ON 11 to 14 V

    NG

    GO TO FUEL INJECTOR CIRCUIT Click here

    OK

  9. CHECK FUEL INJECTOR ASSEMBLY OF MISFIRING CYLINDER


    1. Check the fuel injector 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 of misfiring cylinder Click here.


    NG

    ADJUST VALVE CLEARANCE Click here

    OK

  11. CHECK INTAKE SYSTEM


    1. Check the intake system for vacuum leaks.

      OK
      No leaks in intake system.

    NG

    REPAIR OR REPLACE INTAKE SYSTEM

    OK

  12. CHECK VALVE TIMING


    1. Check the valve timing Click here.


    NG

    ADJUST VALVE TIMING Click here

    OK

  13. CHECK FUEL PRESSURE


    1. Check the fuel pressure Click here.


    NG

    CHECK AND REPLACE FUEL PUMP, PRESSURE REGULATOR, FUEL PIPE LINE AND FILTER

    OK

  14. READ VALUE USING INTELLIGENT TESTER (COOLANT TEMP)


    1. Connect the intelligent tester to the DLC3.

    2. Turn the ignition to ON.

    3. Turn the tester on.

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

  15. INSPECT MANIFOLD ABSOLUTE PRESSURE SENSOR


    1. Inspect the manifold absolute pressure sensor Click here.


    OK

    REPLACE ECM Click here

    NG

    REPLACE MANIFOLD ABSOLUTE PRESSURE SENSOR Click here

  16. CHECK INTAKE SYSTEM


    1. Check the intake system for vacuum leaks.

      OK
      No leaks in intake system.

    NG

    REPAIR OR REPLACE INTAKE SYSTEM

    OK

  17. CHECK VALVE TIMING


    1. Check the valve timing Click here.


    NG

    ADJUST VALVE TIMING Click here

    OK

  18. CHECK FUEL PRESSURE


    1. Check the fuel pressure Click here.


    NG

    CHECK AND REPLACE FUEL PUMP, PRESSURE REGULATOR, FUEL PIPE LINE AND FILTER

    OK

  19. READ VALUE USING INTELLIGENT TESTER (COOLANT TEMP)


    1. Connect the intelligent tester to the DLC3.

    2. Turn the ignition to ON.

    3. Turn the tester on.

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

  20. INSPECT MANIFOLD ABSOLUTE PRESSURE SENSOR


    1. Inspect the manifold absolute pressure sensor Click here.


    NG

    REPLACE MANIFOLD ABSOLUTE PRESSURE SENSOR 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 AND IGNITION


    1. Perform a spark test Click here.

      CAUTION:

      During the test, disconnect all of the fuel injector assembly connectors.

      Note

      Do not crank the engine for more than 2 seconds.


    NG

    CHANGE TO NORMAL SPARK PLUG AND CHECK SPARK OF MISFIRING CYLINDER Click here

    OK

  23. CHECK CYLINDER COMPRESSION PRESSURE OF MISFIRING CYLINDER


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


    NG

    CHECK ENGINE TO DETERMINE CAUSE OF LOW COMPRESSION

    OK

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

    A01VL02E01
    Text in Illustration
    *a

    Front view of wire harness connector

    (to ECM)

    1. 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 Switch Condition Specified Condition
      B87-45 (#10) - A71-21 (E01) Ignition switch ON 11 to 14 V
      B87-46 (#20) - A71-21 (E01) Ignition switch ON 11 to 14 V
      B87-67 (#30) - A71-21 (E01) Ignition switch ON 11 to 14 V

    NG

    GO TO FUEL INJECTOR CIRCUIT Click here

    OK

  25. CHECK FUEL INJECTOR ASSEMBLY OF MISFIRING CYLINDER


    1. Check the fuel injector 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. Inspect the valve clearance of the misfiring cylinder Click here.


    OK

    REPLACE ECM Click here

    NG

    ADJUST VALVE CLEARANCE Click here

  27. CHANGE TO NORMAL SPARK PLUG AND CHECK SPARK OF MISFIRING CYLINDER


    1. Change the installed spark plug to a spark plug that functions normally.

    2. Perform a spark test Click here.

      CAUTION:

      During the test, disconnect all of the fuel injector assembly connectors.

      Note

      Do not crank the engine for more than 2 seconds.


      1. Remove the No. 1 ignition coil from the cylinder head.

      2. Install the spark plug onto the No. 1 ignition coil.

      3. Disconnect all of the fuel injector assembly connectors.

      4. Touch the spark plug to the cylinder head.

      5. Crank the engine for less than 2 seconds and check for spark.

        OK
        Sparks jump across electrode gap.

    OK

    REPLACE SPARK PLUG Click here

    NG

  28. CHANGE TO NORMAL NO. 1 IGNITION COIL AND CHECK SPARK OF MISFIRING CYLINDER


    1. Change the installed No. 1 ignition coil to a known good No. 1 ignition coil.

    2. Perform a spark test Click here.

      CAUTION:

      During the test, disconnect all of the fuel injector assembly connectors.

      Note

      Do not crank the engine for more than 2 seconds.


      1. Remove the No. 1 ignition coil from the cylinder head.

      2. Install the spark plug onto the No. 1 ignition coil.

      3. Disconnect all of the fuel injector assembly connectors.

      4. Touch the spark plug to the cylinder head.

      5. Crank the engine for less than 2 seconds and check for spark.

        OK
        Sparks jump across electrode gap.

    OK

    REPLACE NO.1 IGNITION COIL Click here

    NG

    REPLACE ECM Click here