DTC    P0300    Random / Multiple Cylinder Misfire Detected

DTC    P0301    Cylinder 1 Misfire Detected

DTC    P0302    Cylinder 2 Misfire Detected

DTC    P0303    Cylinder 3 Misfire Detected

DTC    P0304    Cylinder 4 Misfire Detected

for Preparation Click here


DESCRIPTION

A093767E09
When the engine misfires, high concentrations of hydrocarbons (HC) enter the exhaust gas. Extremely high HC concentration levels can cause an increase in exhaust emission levels. Extremely high concentrations of HC can also cause increases in the Three-Way Catalytic Converter (TWC) temperature, which may cause damage to the TWC. 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 TWC reaches the point of thermal degradation, the ECM blinks the MIL. To monitor misfires, the ECM uses both the camshaft position (CMP) sensor and the crankshaft position (CKP) sensor. The CMP sensor is used to identify any misfiring cylinders and the CKP 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
When one of following conditions is detected
(2 trip detection logic):
  1. High temperature misfire occurs in TWC (MIL blinks)
  2. Emission deterioration misfire occurs (MIL illuminates)
  3. Simultaneous misfiring of several cylinders occurs
  1. Open or short in engine wire harness
  2. Connector connections
  3. Vacuum hose connections
  4. Ignition system
  5. Fuel injector assembly
  6. Fuel pressure
  7. Fuel line
  8. Fuel pump assembly
  9. Mass air flow meter
  10. Engine coolant temperature sensor
  11. Compression pressure
  12. Valve timing
  13. PCV valve and hose
  14. PCV hose connections
  15. Intake system
  16. EGR valve assembly
  17. ECM
P0301
P0302
P0303
P0304
When one of following conditions is detected
(2 trip detection logic):
  1. High temperature misfire occurs in TWC (MIL blinks)
  2. Emission deterioration misfire occurs (MIL illuminates)
  3. Misfiring of specific cylinder occurs
When DTCs for misfiring cylinders are randomly set, but DTC P0300 is not set, it indicates that misfires have been detected in different cylinders at different times. DTC P0300 is only set when several misfiring cylinders are detected at the same time.

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. 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.

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

    Engine Speed (rpm)
    		Duration
    Idling
    		5 minutes or more
    1000
    		4 minutes or more
    2000
    		3 minutes or more
    3000
    		2 minutes or more

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

    HINT:
    Do not turn the ignition switch off until the stored 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 will be cleared.

  9. Record the DTC(s), freeze frame data and misfire counts.
  10. Turn the ignition switch off and wait for at least 5 seconds.

WIRING DIAGRAM

Refer to the DTC P0102 for the mass air flow meter circuit (Click here).
Refer to the Fuel Injector Circuit for the fuel injector circuit (Click here).

INSPECTION PROCEDURE

NOTICE:
Inspect the fuses for circuits related to this system before performing the following inspection procedure.

HINT:
  1. If any DTCs other than misfire DTCs are output, troubleshoot those DTCs first.
  2. 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 be helpful in determining whether the vehicle was running or stopped, whether the engine was warmed up or not, whether the air fuel ratio was lean or rich, as well as other data recorded at the time of a malfunction.
  3. 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.
  4. 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.
  5. After finishing repairs, check the misfire counts of the cylinders Cylinder #1 Misfire Count to Cylinder #4 Misfire Count.
  6. Be sure to confirm that no misfiring cylinder DTCs are set again by conducting the confirmation driving pattern after finishing repairs.
  7. When one of Short FT #1, Long FT #1, Short FT #2 or Long FT #2 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).
  8. When the Coolant Temp in the freeze frame data is less than 75°C (167°F), the misfires have occurred only while warming up the engine.
  9. An extremely imbalanced drive wheel which causes body vibration may cause misfire DTCs to be detected.

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

  1. Connect the intelligent tester to the DLC3.

  1. Turn the ignition switch to ON.

  1. Turn the tester on.

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

  1. Read the DTCs.

    HINT:
    Write down the indicated 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

HINT:
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 (HOSE CONNECTIONS)

  1. Check the PCV hose connections (Click here).

OK:
PCV hose is correctly connected and is 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.

  1. Turn the ignition switch to ON.

  1. Turn the tester on.

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

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

    HINT:
    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 MISFIRE COUNT, #2, #3 AND #4)

  1. Connect the intelligent tester to the DLC3.

  1. Turn the ignition switch to ON.

  1. Turn the tester on.

  1. Clear the DTCs (Click here).

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

  1. Allow the engine to idle.

  1. Read each value for Cylinder #1 (to #4) Misfire Count displayed on the tester. If no misfire counts occur in any cylinders, perform the following procedures:

    1. Move the shift lever to D or first gear.

    2. Check the Cylinder #1 (to #4) Misfire Count.

    3. If misfire counts are still not displayed, perform steps "A" and "B" below.

      1. A: Drive the vehicle with the Misfire RPM and Misfire Load noted in the read value using the intelligent tester (Misfire RPM and Misfire Load) procedures above.
      2. B: Read Cylinder #1 (to #4) Misfire Count or the DTCs displayed on the tester.

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

HINT:
  1. 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.
  2. If the freeze frame data record of the engine coolant temperature is below 75°C (167°F), it may only be possible to detect the misfire when the engine is cold.
  3. 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
Go to step 17
A


5.INSPECT SPARK PLUG

  1. Inspect the spark plug of misfire cylinder (Click here).



NG
REPLACE SPARK PLUG (Click here)
OK


6.CHECK FOR SPARKS (SPARK TEST)

  1. Perform the spark test (Click here).



NG
Go to step 34
OK


7.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


8.INSPECT ECM TERMINAL OF MISFIRING CYLINDER (#10, #20, #30 AND/OR #40 VOLTAGE)


    A209787E03

  1. Disconnect the ECM connector.

  1. Turn the ignition switch to ON.

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

    Standard Voltage:
    Tester Connection
    		Switch Condition
    		Specified Condition
    B8-86 (#10) - B8-46 (E01)
    		Ignition switch ON
    		11 to 14 V
    B8-85 (#20) - B8-46 (E01)
    		Ignition switch ON
    		11 to 14 V
    B8-84 (#30) - B8-46 (E01)
    		Ignition switch ON
    		11 to 14 V
    B8-83 (#40) - B8-46 (E01)
    		Ignition switch ON
    		11 to 14 V

    Text in Illustration 
    *a
    		Front view of wire harness connector
    (to ECM)

  1. Reconnect the ECM connector.



NG
CHECK FUEL INJECTOR CIRCUIT (Click here)
OK


9.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
REPLACE FUEL INJECTOR ASSEMBLY (Click here)
OK


10.CHECK INTAKE SYSTEM

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

    OK:
    No leaks in intake system.



NG
REPAIR OR REPLACE INTAKE SYSTEM (Click here)
OK


11.CHECK FUEL PRESSURE

  1. Check the fuel pressure (Click here).



NG
Go to step 36
OK


12.READ VALUE USING INTELLIGENT TESTER (COOLANT TEMP)

  1. Connect the intelligent tester to the DLC3.

  1. Turn the ignition switch to ON.

  1. Turn the tester on.

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

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

    Standard value:
    With cold engine:
    Same as ambient air temperature.
    With warm engine:
    80 to 100°C (176 to 212°F).



NG
REPLACE ENGINE COOLANT TEMPERATURE SENSOR (Click here)
OK


13.READ VALUE USING INTELLIGENT TESTER (MAF)

  1. Connect the intelligent tester to the DLC3.

  1. Start the engine.

  1. Turn the tester on.

  1. Enter the following menus: Powertrain / Engine and ECT / Data List / MAF and Coolant Temp.

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

  1. Read MAF with the engine speed at 2500 rpm.

    Standard:
    Between 2.3 gm/sec and 6.0 gm/sec (shift lever: neutral; A/C: Off).



NG
Go to step 29
OK


14.CHECK VALVE TIMING
A187739E02

  1. Remove the cylinder head cover (Click here).

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

  1. Check that the alignment mark of the camshaft timing sprocket is in the position shown in the illustration.

    HINT:
    If not, turn the crankshaft damper 1 revolution (360°) to align the alignment mark and sprocket as above.

    OK:
    Alignment marks on camshaft timing gears are aligned as shown in the illustration

Text in Illustration 
*1
Mark Plate
*2
Alignment Mark
*a
Reference Camshaft Layout
*b
No. 1 Cylinder at TDC Compression

  1. Reinstall the cylinder head cover (Click here).



NG
ADJUST VALVE TIMING (Click here)
OK


15.PERFORM ACTIVE TEST USING INTELLIGENT TESTER (CONTROL THE EGR STEP POSITION)

  1. Connect the intelligent tester to the DLC3.

  1. Turn the ignition switch to ON.

  1. Turn the tester on.

  1. Start the engine and warm it up until the engine coolant temperature reaches 75°C (167°F) or more.

    HINT:
    The A/C switch and all accessory switches should be off.

  1. Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the EGR Step Position.

  1. Check the MAP and Engine Speed in Date List at the idling condition while performing Active Test.

    OK:
    MAP and idling condition change in response to EGR step position.


    Standard:

    -
    		EGR Step Position (Active Test)
    0 Steps
    		0 to 30 Steps
    Idling condition
    		Steady idling
    		Idling changes from steady to rough idling
    MAP
    (Data List)
    		MAP value is 20 to 40 kPa (150 to 300 mmHg)
    (EGR valve is fully closed)
    		MAP value is at least +10 kPa (75 mmHg) higher than when EGR valve is fully closed

    HINT:
    1. Do not leave the EGR valve open for 10 seconds or more during the Active Test.
    2. Be sure to return the EGR valve to step 0 when Active Test is completed.

    Result 
    Result
    		Proceed to
    NG
    		A
    OK
    		B



B
Go to step 29
A


16.INSPECT EGR VALVE ASSEMBLY

  1. Remove the EGR valve assembly (Click here).

  1. Check if the EGR valve is stuck open.

    OK:
    EGR valve is tightly closed (it is not stuck open).

  1. Reinstall the EGR valve assembly (Click here).



OK
Go to step 29

NG
REPLACE EGR VALVE ASSEMBLY (Click here)

17.CHECK INTAKE SYSTEM

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

    OK:
    No leaks in intake system.



NG
REPAIR OR REPLACE INTAKE SYSTEM (Click here)
OK


18.CHECK FUEL PRESSURE

  1. Check the fuel pressure (Click here).



NG
Go to step 36
OK


19.READ VALUE USING INTELLIGENT TESTER (COOLANT TEMP)

  1. Connect the intelligent tester to the DLC3.

  1. Turn the ignition switch to ON.

  1. Turn the tester on.

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

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

    Standard value:
    With cold engine:
    Same as ambient air temperature.
    With warm engine:
    80 to 100°C (176 to 212°F).



NG
REPLACE ENGINE COOLANT TEMPERATURE SENSOR (Click here)
OK


20.READ VALUE USING INTELLIGENT TESTER (MAF)

  1. Connect the intelligent tester to the DLC3.

  1. Start the engine.

  1. Turn the tester on.

  1. Enter the following menus: Powertrain / Engine and ECT / Data List / MAF and Coolant Temp.

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

  1. Read MAF with the engine speed at 2500 rpm.

    Standard:
    Between 2.3 gm/sec and 6.0 gm/sec (shift lever: neutral; A/C: Off).



NG
Go to step 29
OK


21.CHECK VALVE TIMING
A187739E02

  1. Remove the cylinder head cover (Click here).

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

  1. Check that the alignment mark of the camshaft timing sprocket is in the position shown in the illustration.

    HINT:
    If not, turn the crankshaft damper 1 revolution (360°) to align the alignment mark and sprocket as above.

    OK:
    Alignment marks on camshaft timing gears are aligned as shown in the illustration

Text in Illustration 
*1
Mark Plate
*2
Alignment Mark
*a
Reference Camshaft Layout
*b
No. 1 Cylinder at TDC Compression

  1. Reinstall the cylinder head cover (Click here).



NG
ADJUST VALVE TIMING (Click here)
OK


22.READ VALUE USING INTELLIGENT TESTER (CONTROL THE EGR STEP POSITION)

  1. Connect the intelligent tester to the DLC3.

  1. Turn the ignition switch to ON.

  1. Turn the tester on.

  1. Start the engine and warm it up until the engine coolant temperature reaches 75°C (167°F) or more.

    HINT:
    The A/C switch and all accessory switches should be off.

  1. Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the EGR Step Position.

  1. Check the MAP and Engine Speed in Date List at the idling condition while performing Active Test.

    OK:
    MAP and idling condition change in response to EGR step position.


    Standard:

    -
    		EGR Step Position (Active Test)
    0 Steps
    		0 to 30 Steps
    Idling condition
    		Steady idling
    		Idling changes from steady to rough idling
    MAP
    (Data List)
    		MAP value is 20 to 40 kPa (150 to 300 mmHg)
    (EGR valve is fully closed)
    		MAP value is at least +10 kPa (75 mmHg) higher than when EGR valve is fully closed

    HINT:
    1. Do not leave the EGR valve open for 10 seconds or more during the Active Test.
    2. Be sure to return the EGR valve to step 0 when Active Test is completed.

    Result 
    Result
    		Proceed to
    NG
    		A
    OK
    		B



B
Go to step 24
A


23.INSPECT EGR VALVE ASSEMBLY

  1. Remove the EGR valve assembly (Click here).

  1. Check if the EGR valve is stuck open.

    OK:
    EGR valve is tightly closed (it is not stuck open).

  1. Reinstall the EGR valve assembly (Click here).



NG
REPLACE EGR VALVE ASSEMBLY (Click here)
OK


24.INSPECT SPARK PLUG

  1. Inspect the spark plugs (Click here).



NG
REPLACE SPARK PLUG (Click here)
OK


25.CHECK FOR SPARKS (SPARK TEST)

  1. Perform the spark test (Click here).



NG
Go to step 34
OK


26.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


27.INSPECT ECM TERMINAL OF MISFIRING CYLINDER (#10, #20, #30 AND/OR #40 VOLTAGE)


    A209787E03

  1. Disconnect the ECM connector.

  1. Turn the ignition switch to ON.

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

    Standard Voltage:
    Tester Connection
    		Switch Condition
    		Specified Condition
    B8-86 (#10) - B8-46 (E01)
    		Ignition switch ON
    		11 to 14 V
    B8-85 (#20) - B8-46 (E01)
    		Ignition switch ON
    		11 to 14 V
    B8-84 (#30) - B8-46 (E01)
    		Ignition switch ON
    		11 to 14 V
    B8-83 (#40) - B8-46 (E01)
    		Ignition switch ON
    		11 to 14 V

    Text in Illustration 
    *a
    		Front view of wire harness connector
    (to ECM)

  1. Reconnect the ECM connector.



NG
CHECK FUEL INJECTOR CIRCUIT (Click here)
OK


28.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
REPLACE FUEL INJECTOR ASSEMBLY (Click here)
OK


29.CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER CONNECTOR CONNECTION)

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


NEXT


30.CHECK WHETHER DTC OUTPUT RECURS

  1. Perform the confirmation driving pattern.

    HINT:
    Refer to the CONFIRMATION DRIVING PATTERN.

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

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

  1. Check the DTC judgment result.
    Result 
    Result
    		Proceed to
    ABNORMAL
    (P0300, P0301, P0302, P0303, or P0304 outputs)
    		A
    NORMAL
    (No DTCs output)
    		B



B
END
A


31.CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER - ECM)

  1. Disconnect the mass air flow meter connector.

  1. Disconnect the ECM connector.

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

    Standard Resistance (Check for Open):
    Tester Connection
    		Condition
    		Specified Condition
    B53-5 (VG) - B8-69 (VG)
    		Always
    		Below 1 Ω
    B53-4 (E2G) - B8-92 (E2G)

    Standard Resistance (Check for Short):
    Tester Connection
    		Condition
    		Specified Condition
    B53-5 (VG) or B8-69 (VG) - Body ground
    		Always
    		10 kΩ or higher

  1. Reconnect the mass air flow meter connector.

  1. Reconnect the ECM connector.



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK


32.REPLACE MASS AIR FLOW METER

  1. Replace the mass air flow meter (Click here).

    HINT:
    If the results of the inspection performed in step 13 and step 20 indicated no problem, proceed to the next step without replacing the mass air flow meter.


NEXT


33.CHECK WHETHER DTC OUTPUT RECURS

  1. Perform the confirmation driving pattern.

    HINT:
    Refer to the CONFIRMATION DRIVING PATTERN.

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

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

  1. Check the DTC judgment result.
    Result 
    Result
    		Proceed to
    NORMAL
    (No DTCs output)
    		A
    ABNORMAL
    (P0300, P0301, P0302, P0303, or P0304 outputs)
    		B



B
REPLACE ECM (Click here)
A

END 

34.CHANGE TO NORMALLY FUNCTIONING SPARK PLUG AND CHECK SPARK OF MISFIRING CYLINDER


    A200758

  1. Change the installed spark plug to a normally functioning spark plug.

  1. Perform a spark test.

    CAUTION:
    Always disconnect all injector connectors.

    NOTICE:
    Do not crank the engine for more than 2 seconds.

    1. Install the spark plug into the ignition coil assembly and connect the ignition coil assembly connector.

    2. Disconnect the fuel injector assembly connectors.

    3. Touch the spark plug to the cylinder head.

    4. Check if sparks occur while the engine is being cranked.

      OK:
      Sparks jump across electrode gap.



NG
Go to step 35
OK

REPLACE SPARK PLUG (Click here)  

35.CHANGE TO NORMALLY FUNCTIONING IGNITION COIL AND CHECK SPARK OF MISFIRING CYLINDER


    A200758

  1. Change the ignition coil assembly to a normally functioning ignition coil assembly.

  1. Perform a spark test.

    CAUTION:
    Always disconnect all injector connectors.

    NOTICE:
    Do not crank the engine for more than 2 seconds.

    1. Install the spark plug into the ignition coil assembly and connect the ignition coil assembly connector.

    2. Disconnect the fuel injector assembly connector.

    3. Touch the spark plug to the cylinder head.

    4. Check if sparks occur while the engine is being cranked.

      OK:
      Sparks jump across electrode gap.



NG
REPLACE ECM (Click here)
OK

REPLACE IGNITION COIL ASSEMBLY (Click here)  

36.CHECK FUEL LINE

  1. Check the fuel lines for leaks or blockage.

    OK:
    No leaks and blockage.



NG
REPAIR OR REPLACE FUEL LINE
OK

REPLACE FUEL PUMP ASSEMBLY (Click here)