SFI SYSTEM, Diagnostic DTC:P0300,P0301,P0302,P0303 and 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 either 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 connections Vacuum hose connections Ignition system Fuel injector assembly Fuel pressure Fuel line Fuel pump Mass air flow meter Engine coolant temperature sensor Compression pressure Valve timing PCV valve and hose PCV hose connections Intake system ECM
P0301 P0302 P0303 P0304	Misfiring of specific cylinder occurs and either 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.

WIRING DIAGRAM

Refer to DTC P0102 (Click here).

Refer to Fuel Injector Circuit (Click here).

CONFIRMATION DRIVING PATTERN

Connect the GTS to the DLC3.
Turn the ignition switch to ON.
Turn the GTS on.
Record the DTC(s) and freeze frame data.
Using the GTS, switch the ECM from normal mode to check mode (Click here).
Read the misfire counts of each cylinder (cylinder No. 1 to No. 4) with the engine idling. If any misfire count (Cylinder #1 Misfire Count to Cylinder #4 Misfire Count) is displayed, skip the following confirmation driving pattern.

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

Tip:

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


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

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

Tip:
Do not turn the ignition switch off until the stored DTCs and freeze frame data have been recorded. When the ECM returns to normal mode (default), the stored DTCs, freeze frame data and other data will be cleared.
Record the DTCs, freeze frame data and misfire counts.
Turn the ignition switch off and wait for at least 30 seconds.
Clear the DTCs (Click here).

CAUTION / NOTICE / HINT

Tip:

Check the "Fuel Cut Elps Time" in the Data List or the Freeze Frame Data. If the elapsed time is over 0 seconds, then the engine speed is high (engine speed at which fuel cut occurs + 500 rpm). When this has happened, there is the possibility that the valve rocker arm will become loose and a fire could start, so check that the valve rocker arm is properly attached (Click here).
By clearing the DTC, "Fuel Cut Elps Time" will be cleared.
If any DTCs other than misfire DTCs are output, troubleshoot those DTCs first.
Read freeze frame data using the GTS. 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. The fuel level is low.
2. Improper fuel is being used.
3. The spark plugs are dirty.
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 the Coolant Temp in the freeze frame data is below 75°C (167°F), the misfire has occurred only while warming up the engine.
An extremely imbalanced drive wheel which causes body vibration may cause misfire DTCs detection.

PROCEDURE

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

Connect the GTS to the DLC3.
Turn the ignition switch to ON.
Turn the GTS on.
Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.
Read the DTCs.

Tip:
Write down the indicated DTCs.

Table 1. 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

Tip:

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

GO TO DTC CHART

(Click here)

CHECK PCV HOSE CONNECTIONS
1. Check the PCV hose connections (Click here).
OK

PCV hose is correctly connected and is not damaged.
REPAIR OR REPLACE PCV HOSE
READ VALUE USING GTS (MISFIRE RPM AND MISFIRE LOAD)
1. Connect the GTS to the DLC3.
2. Turn the ignition switch to ON.
3. Turn the GTS on.
4. Enter the following menus: Powertrain / Engine and ECT / Data List / Misfire RPM and Misfire Load.
5. Read and note the Misfire RPM and Misfire Load values.
  
  Tip:
  The Misfire RPM and Misfire Load values indicate the vehicle conditions under which the misfire occurred.

READ VALUE USING GTS (MISFIRE COUNT)

Connect the GTS to the DLC3.
Turn the ignition switch to ON.
Turn the GTS on.
Clear the DTCs (Click here).
Enter the following menus: Powertrain / Engine and ECT / Data List / Cylinder #1 Misfire Count to Cylinder #4 Misfire Count.
Allow the engine to idle.
Read each value for Cylinder #1 Misfire Count to Cylinder #4 Misfire Count displayed on the GTS. If no misfire counts occur in any cylinders, perform steps (h) and (i) and then check the misfire counts again.
Drive the vehicle with the Misfire RPM and Misfire Load noted in the "Read Value Using GTS (Misfire RPM and Misfire Load)" procedures above.
Read the Cylinder #1 Misfire Count to Cylinder #4 Misfire Count or DTCs displayed on the GTS.

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

Tip:

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 less than 120 seconds, the misfire may be detected immediately after the engine is started.

CHECK INTAKE SYSTEMClick here

INSPECT SPARK PLUG
1. Inspect the spark plug of the misfiring cylinder (Click here).
  
  Tip:
  Perform "Inspection After Repair" after replacing the spark plug (Click here).
REPLACE SPARK PLUG

(Click here)
CHECK FOR SPARKS (SPARK TEST)
1. Perform a spark test (Click here).
  Tip:
  - If the result of the spark test is normal, proceed to the next step.
  - Perform "Inspection After Repair" after repairing or replacing the ignition system (Click here).
CHECK CYLINDER COMPRESSION PRESSURE
1. Measure the cylinder compression pressure of the misfiring cylinder (Click here).
  
  Tip:
  Perform "Inspection After Repair" after repairing or replacing the engine assembly (Click here).
CHECK ENGINE TO DETERMINE CAUSE OF LOW COMPRESSION

CHECK FUEL INJECTOR ASSEMBLY (POWER SOURCE)

Disconnect the fuel injector assembly connector.
Turn the ignition switch to ON.

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

Standard Voltage


Tester Connection	Switch Condition	Specified Condition
C13-1 - Body ground	Ignition switch ON	11 to 14 V
C15-1 - Body ground	Ignition switch ON	11 to 14 V
C17-1 - Body ground	Ignition switch ON	11 to 14 V
C19-1 - Body ground	Ignition switch ON	11 to 14 V

Table 3. Text in Illustration
*a	Front view of wire harness connector (to Fuel Injector Assembly)

Reconnect the fuel injector assembly connector.

CHECK FUEL INJECTOR CIRCUIT

(Click here)

CHECK HARNESS AND CONNECTOR (FUEL INJECTOR ASSEMBLY - ECM)

Disconnect the fuel injector assembly connector.
Disconnect the ECM connector.

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

Standard Resistance (Check for Open)


Tester Connection	Condition	Specified Condition
C13-2 - C111-98 (#10)	Always	Below 1 Ω
C15-2 - C111-95 (#20)	Always	Below 1 Ω
C17-2 - C111-96 (#30)	Always	Below 1 Ω
C19-2 - C111-97 (#40)	Always	Below 1 Ω

Standard Resistance (Check for Short)


Tester Connection	Condition	Specified Condition
C13-2 or C111-98 (#10) - Body ground	Always	10 kΩ or higher
C15-2 or C111-95 (#20) - Body ground	Always	10 kΩ or higher
C17-2 or C111-96 (#30) - Body ground	Always	10 kΩ or higher
C19-2 or C111-97 (#40) - Body ground	Always	10 kΩ or higher

Reconnect the fuel injector assembly connector.
Reconnect the ECM connector.

REPAIR OR REPLACE HARNESS OR CONNECTOR (FUEL INJECTOR ASSEMBLY - ECM)

CHECK FUEL INJECTOR ASSEMBLY 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).
  
  Tip:
  Perform "Inspection After Repair" after replacing the fuel injector assembly (Click here).
REPLACE FUEL INJECTOR ASSEMBLY

(Click here)
CHECK INTAKE SYSTEM
1. Check the intake system for vacuum leaks (Click here).
  
  OK
  
  No leaks in the intake system.
  
  Tip:
  Perform "Inspection After Repair" after repairing or replacing the intake system (Click here).
REPAIR OR REPLACE INTAKE SYSTEM
CHECK FUEL PRESSURE
1. Check the fuel pressure (Click here).
CHECK FUEL LINEClick here
READ VALUE USING GTS (COOLANT TEMP)
1. Connect the GTS to the DLC3.
2. Turn the ignition switch to ON.
3. Turn the GTS on.
4. Enter the following menus: Powertrain / Engine and ECT / Data List / Coolant Temp.
5. Read the Coolant Temp twice, when the engine is both cold and warmed up.
  
  Standard
  
  With cold engine
  
  Same as ambient air temperature.
  
  With warm engine
  
  Between 75°C and 100°C (167°F and 212°F).
  
  Tip:
  Perform "Inspection After Repair" after replacing the engine coolant temperature sensor (Click here).
REPLACE ENGINE COOLANT TEMPERATURE SENSOR

(Click here)
READ VALUE USING GTS (MAF)
1. Connect the GTS to the DLC3.
2. Start the engine.
3. Turn the GTS on.
4. Enter the following menus: Powertrain / Engine and ECT / Data List / Engine Speed, MAF and Coolant Temp.
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
  
  Between 6.5 gm/sec and 10.5 gm/sec (shift lever: N (for CVT), or neutral (for M/T), A/C: Off).
CHECK HARNESS AND CONNECTORClick here
CHECK ENGINE MECHANICAL SYSTEM
1. Check for mechanical malfunctions that affect the valve timing, such as a jumped tooth or stretching of the timing chain (Click here).
REPAIR OR REPLACE MALFUNCTIONING PARTS, COMPONENT AND AREA

CHECK WHETHER DTC OUTPUT RECURS (P0300, P0301, P0302, P0303 OR P0304)

Connect the GTS to the DLC3.
Turn the ignition switch to ON.
Turn the GTS on.
Clear the DTCs (Click here).
Turn the ignition switch off and wait for 30 seconds.
Turn the ignition switch to ON and turn the GTS on.
Start the engine and warm it up.
Drive the vehicle referring to the Confirmation Driving Pattern.
Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.
Input the DTC: P0300, P0301, P0302, P0303 or P0304.
Check the DTC judgment result.

Table 4. Result
Result	Proceed to
ABNORMAL (DTC P0300, P0301, P0302, P0303 or P0304 is output)	A
NORMAL (DTC is not output)	B

CHECK HARNESS AND CONNECTORClick here

END

CHECK INTAKE SYSTEM
1. Check the intake system for vacuum leaks (Click here).
  
  OK
  
  No leaks in the intake system
  
  Tip:
  Perform "Inspection After Repair" after repairing or replacing the intake system (Click here).
REPAIR OR REPLACE INTAKE SYSTEM
CHECK FUEL PRESSURE
1. Check the fuel pressure (Click here).
CHECK FUEL LINEClick here
READ VALUE USING GTS (COOLANT TEMP)
1. Connect the GTS to the DLC3.
2. Turn the ignition switch to ON.
3. Turn the GTS on.
4. Enter the following menus: Powertrain / Engine and ECT / Data List / Coolant Temp.
5. Read the Coolant Temp twice, when the engine is both cold and warmed up.
  
  Standard
  
  With cold engine
  
  Same as ambient air temperature.
  
  With warm engine
  
  Between 75°C and 100°C (167°F and 212°F).
  
  Tip:
  Perform "Inspection After Repair" after replacing the engine coolant temperature sensor (Click here).
REPLACE ENGINE COOLANT TEMPERATURE SENSOR

(Click here)
READ VALUE USING GTS (MAF)
1. Connect the GTS to the DLC3.
2. Start the engine.
3. Turn the GTS on.
4. Enter the following menus: Powertrain / Engine and ECT / Data List / Engine Speed, MAF and Coolant Temp.
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
  
  Between 6.5 gm/sec and 10.5 gm/sec (shift lever: N (for CVT), or neutral (for M/T), A/C: Off).
CHECK HARNESS AND CONNECTORClick here
INSPECT SPARK PLUG
1. Inspect the spark plug of the misfiring cylinder (Click here).
  
  Tip:
  Perform "Inspection After Repair" after replacing the spark plug (Click here).
REPLACE SPARK PLUG

(Click here)
CHECK FOR SPARKS (SPARK TEST)
1. Perform a spark test (Click here).
  Tip:
  - If the result of the spark test is normal, proceed to the next step.
  - Perform "Inspection After Repair" after repairing or replacing the ignition system (Click here).
CHECK CYLINDER COMPRESSION PRESSURE
1. Measure the cylinder compression pressure of the misfiring cylinder (Click here).
  
  Tip:
  Perform "Inspection After Repair" after repairing or replacing the engine assembly (Click here).
CHECK ENGINE TO DETERMINE CAUSE OF LOW COMPRESSION

CHECK FUEL INJECTOR ASSEMBLY (POWER SOURCE)

Disconnect the fuel injector assembly connector.
Turn the ignition switch to ON.

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

Standard Voltage


Tester Connection	Switch Condition	Specified Condition
C13-1 - Body ground	Ignition switch ON	11 to 14 V
C15-1 - Body ground	Ignition switch ON	11 to 14 V
C17-1 - Body ground	Ignition switch ON	11 to 14 V
C19-1 - Body ground	Ignition switch ON	11 to 14 V

Table 5. Text in Illustration
*a	Front view of wire harness connector (to Fuel Injector Assembly)

Reconnect the fuel injector assembly connector.

CHECK FUEL INJECTOR CIRCUIT

(Click here)

CHECK HARNESS AND CONNECTOR (FUEL INJECTOR ASSEMBLY - ECM)

Disconnect the fuel injector assembly connector.
Disconnect the ECM connector.

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

Standard Resistance (Check for Open)


Tester Connection	Condition	Specified Condition
C13-2 - C111-98 (#10)	Always	Below 1 Ω
C15-2 - C111-95 (#20)	Always	Below 1 Ω
C17-2 - C111-96 (#30)	Always	Below 1 Ω
C19-2 - C111-97 (#40)	Always	Below 1 Ω

Standard Resistance (Check for Short)


Tester Connection	Condition	Specified Condition
C13-2 or C111-98 (#10) - Body ground	Always	10 kΩ or higher
C15-2 or C111-95 (#20) - Body ground	Always	10 kΩ or higher
C17-2 or C111-96 (#30) - Body ground	Always	10 kΩ or higher
C19-2 or C111-97 (#40) - Body ground	Always	10 kΩ or higher

Reconnect the fuel injector assembly connector.
Reconnect the ECM connector.

REPAIR OR REPLACE HARNESS OR CONNECTOR (FUEL INJECTOR ASSEMBLY - ECM)

CHECK FUEL INJECTOR ASSEMBLY 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).
  
  Tip:
  Perform "Inspection After Repair" after replacing the fuel injector assembly (Click here).
REPLACE FUEL INJECTOR ASSEMBLY

(Click here)
CHECK ENGINE MECHANICAL SYSTEM
1. Check for mechanical malfunctions that affect the valve timing, such as a jumped tooth or stretching of the timing chain (Click here).
REPAIR OR REPLACE MALFUNCTIONING PARTS, COMPONENT AND AREA

CHECK WHETHER DTC OUTPUT RECURS (DTC P0300, P0301, P0302, P0303 OR P0304)

Connect the GTS to the DLC3.
Turn the ignition switch to ON.
Turn the GTS on.
Clear the DTCs (Click here).
Turn the ignition switch off and wait for 30 seconds.
Turn the ignition switch to ON and turn the GTS on.
Start the engine and warm it up.
Drive the vehicle referring to the Confirmation Driving Pattern.
Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.
Input the DTC: P0300, P0301, P0302, P0303 or P0304.
Check the DTC judgment result.

Table 6. Result
Result	Proceed to
ABNORMAL (DTC P0300, P0301, P0302, P0303 or P0304 is output)	A
NORMAL (DTC is not output)	B

END

CHECK HARNESS AND CONNECTOR
1. Check the connection and terminal contact pressure of connectors and wire harnesses between the mass air flow meter and ECM (Click here).
  
  Tip:
  Repair any problems.

CHECK WHETHER DTC OUTPUT RECURS (DTC P0300, P0301, P0302, P0303 OR P0304)

Connect the GTS to the DLC3.
Turn the ignition switch to ON.
Turn the GTS on.
Clear the DTCs (Click here).
Turn the ignition switch off and wait for 30 seconds.
Turn the ignition switch to ON and turn the GTS on.
Start the engine and warm it up.
Drive the vehicle referring to the Confirmation Driving Pattern.
Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.
Input the DTC: P0300, P0301, P0302, P0303 or P0304.
Check the DTC judgment result.

Table 7. Result
Result	Proceed to
ABNORMAL (DTC P0300, P0301, P0302, P0303 or P0304 is output)	A
NORMAL (DTC is not output)	B

END

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

Disconnect the mass air flow meter connector.
Disconnect the ECM connector.

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

Standard Resistance (Check for Open)


Tester Connection	Condition	Specified Condition
C3-5 (VG) - C111-137 (VG)	Always	Below 1 Ω
C3-4 (E2G) - C111-104 (E2G)	Always	Below 1 Ω

Standard Resistance (Check for Short)


Tester Connection	Condition	Specified Condition
C3-5 (VG) or C111-137 (VG) - Body ground	Always	10 kΩ or higher

Reconnect the mass air flow meter connector.
Reconnect the ECM connector.

REPAIR OR REPLACE HARNESS OR CONNECTOR (MASS AIR FLOW METER - ECM)

REPLACE MASS AIR FLOW METER
1. Replace the mass air flow meter (Click here).
  Tip:
  - If the results of the inspections performed in steps 14 and 20 indicated no problem, proceed to the next step without replacing the mass air flow meter.
  - Perform "Inspection After Repair" after replacing the mass air flow meter (Click here).

CONFIRM WHETHER MALFUNCTION HAS BEEN SUCCESSFULLY REPAIRED

Connect the GTS to the DLC3.
Turn the ignition switch to ON.
Turn the GTS on.
Clear the DTCs (Click here).
Turn the ignition switch off and wait for 30 seconds.
Turn the ignition switch to ON and turn the GTS on.
Start the engine and warm it up.
Drive the vehicle referring to the Confirmation Driving Pattern.
Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.
Input the DTC: P0300, P0301, P0302, P0303 or P0304.
Check the DTC judgment result.

Table 8. Result
Result	Proceed to
ABNORMAL (DTC P0300, P0301, P0302, P0303 or P0304 is output)	A
NORMAL (DTC is not output)	B

REPLACE ECM

(Click here)

END

CHECK FUEL LINE
1. Check the fuel lines for leaks or blockage.
  
  Tip:
  Perform "Inspection After Repair" after replacing the fuel pump (Click here).
REPLACE FUEL PUMP

(Click here Click here)

REPAIR OR REPLACE FUEL LINE