P0304
2GR-FE ENGINE CONTROL SYSTEM: SFI SYSTEM: P0300-P0306: Random / Multiple Cylinder Misfire Detected
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
DTC P0305 - Cylinder 5 Misfire Detected
DTC P0306 - Cylinder 6 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 VVT sensor and the crankshaft position sensor. The VVT 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.
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 sets a DTC when either one of the following conditions, which could cause emission deterioration, is detected (2 trip detection logic).
- Within the first 1000 crankshaft revolutions of the engine starting, an excessive misfiring rate (approximately 20 to 50 misfires per 1000 crankshaft revolutions) occurs once.
- An excessive misfiring rate (approximately 20 to 50 misfires per 1000 crankshaft revolutions) occurs a total of 4 times.
The ECM flashes the MIL and sets a DTC when either one of the following conditions, which could cause the three-way catalytic converter damage, is detected (2 trip detection logic).
- At a high engine speed, a catalyst damage misfire, which monitored every 200 crankshaft revolutions, occurs once.
- At a normal engine speed, a catalyst damage misfire, which monitored every 200 crankshaft revolutions, occurs 3 times.
HINT
If a catalyst damage misfire occurs, the ECM informs the driver by flashing the MIL.
MONITOR STRATEGY
TYPICAL ENABLING CONDITIONS
Monitor period of emission-related misfire:
Monitor period of catalyst-damaged misfire (MIL blinks):
TYPICAL MALFUNCTION THRESHOLDS
Monitor period of emission-related misfire:
Monitor period of catalyst-damaged misfire (MIL blinks):
MONITOR RESULT
Refer to CHECKING MONITOR STATUS Mode 6 Data.
CONFIRMATION DRIVING PATTERN
1. Connect the Techstream to the DLC3.
2. Turn the engine switch on (IG).
3. Turn the Techstream on.
4. Record the DTC(s) and freeze frame data.
5. Clear DTCs (even if no DTCs are stored, perform the clear DTC procedure).
6. Using the Techstream, switch the ECM from normal mode to check mode Check Mode Procedure.
7. Read the misfire counts of each cylinder (Cylinder #1 Misfire Count to Cylinder #6 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.
HINT
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.
9. Check whether misfires have occurred by checking DTCs and freeze frame data.
HINT
Do not turn the engine 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 erased.
10. Record the DTC(s), freeze frame data and misfire counts.
11. Turn the engine 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 Fuel Injector Circuit Fuel Injector Circuit.
Refer to DTC P0102 P0102.
INSPECTION PROCEDURE
NOTICE:
Inspect the fuses for circuits related to this system before performing the following inspection procedure.
HINT
- If any DTCs other than misfire DTCs are output, troubleshoot those DTCs first.
- Read freeze frame data using the Techstream. 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 #6 Misfire Count).
- Be sure to confirm that no misfiring cylinder DTCs are stored again by conducting the confirmation driving pattern after finishing repairs.
- For 6 cylinder engine, the ECM intentionally does not set the specific misfiring cylinder DTCs at high engine speed. If misfires occur only in high engine speed areas, only DTC P0300 is set.
In the event of DTC P0300 being present, perform the following operations:
(1) Clear the DTCs Reading and Clearing Diagnostic Trouble Codes.
(2) Start the engine and conduct the confirmation driving pattern.
(3) Read the misfiring rates of each cylinder or DTC(s) using the Techstream.
(4) Repair the cylinder(s) that has a high misfiring rate or is indicated by the DTC.
(5) After finishing repairs, conduct the confirmation driving pattern again, in order to verify that DTC P0300 is not set.
- 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 +/-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 less than 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 DTC OUTPUT (IN ADDITION TO MISFIRE CODES)
(a) Connect the Techstream to the DLC3.
(b) Turn the engine switch on (IG).
(c) Turn the Techstream on.
(d) Enter the following menus: Powertrain / Engine / Trouble Codes.
(e) Read DTCs.
Result:
HINT
If any DTCs other than P0300, P0301, P0302, P0303, P0304, P0305 and P0306 are output, troubleshoot those DTCs first.
B -- GO TO DTC CHART SFI System
A -- Continue to next step.
2. CHECK PCV HOSE (HOSE CONNECTIONS)
(a) Check the PCV hose connections On-Vehicle Inspection.
OK:
PCV hose is correctly connected and is not damaged.
NG -- REPAIR OR REPLACE PCV HOSE
OK -- Continue to next step.
3. READ VALUE USING TECHSTREAM (MISFIRE RPM AND MISFIRE LOAD)
(a) Connect the Techstream to the DLC3.
(b) Turn the engine switch on (IG) and turn the Techstream on.
(c) Enter the following menus: Powertrain / Engine / Data List / Misfire RPM and Misfire Load.
(d) 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 -- Continue to next step.
4. READ VALUE USING TECHSTREAM (CATALYST OT MF F/C)
(a) Connect the Techstream to the DLC3.
(b) Turn the engine switch on (IG) and turn the Techstream on.
(c) Enter the following menus: Powertrain / Engine / Data List / Catalyst OT MF F/C.
(d) Read the value displayed on the Techstream.
Result:
B -- READ VALUE USING TECHSTREAM (MISFIRE COUNT)
A -- Continue to next step.
5. PERFORM ACTIVE TEST USING TECHSTREAM
(a) Connect the Techstream to the DLC3.
(b) Turn the engine switch on (IG) and turn the Techstream on.
(c) Enter the following menus: Powertrain / Engine / Active Test / Prohibit the Catalyst OT Misfire Prevent F/C.
(d) Perform the Active Test.
NOTICE:
When performing the Active Test, make sure the vehicle is stopped and the engine is either idling or being revved at 3000 rpm or less.
NEXT -- Continue to next step.
6. READ VALUE USING TECHSTREAM (MISFIRE COUNT)
(a) Connect the Techstream to the DLC3.
(b) Turn the engine switch on (IG).
(c) Turn the Techstream on.
(d) Enter the following menus: Powertrain / Engine / Data List / Cylinder #1 Misfire Count, Cylinder #2 Misfire Count, Cylinder #3 Misfire Count, Cylinder #4 Misfire Count, Cylinder #5 Misfire Count and Cylinder #6 Misfire Count.
(e) Start the engine and allow the engine to idle.
(f) Read each value for Cylinder #1 Misfire Count to Cylinder #6 Misfire Count displayed on the Techstream. If no misfire counts occur in any cylinders, perform procedure [A] and [B] and then check the misfire counts again.
(g) Drive the vehicle with the Misfire RPM and Misfire Load noted in the "Read Value Using Techstream (Misfire RPM And Misfire Load)" procedures above [A].
(h) Read the Cylinder #1 Misfire Count to Cylinder #6 Misfire Count or DTCs displayed on the Techstream [B].
Result
HINT
- 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 less than 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 AIR INDUCTION SYSTEM
A -- Continue to next step.
7. INSPECT SPARK PLUG
(a) Inspect the spark plug of the misfiring cylinder Testing and Inspection.
NG -- REPLACE SPARK PLUG Removal
OK -- Continue to next step.
8. CHECK FOR SPARK (SPARK TEST)
(a) Perform a spark test Testing and Inspection.
HINT
If the result of the spark test is normal, proceed to the next step.
NEXT -- Continue to next step.
9. CHECK CYLINDER COMPRESSION PRESSURE
(a) Measure the cylinder compression pressure of the misfiring cylinder On-Vehicle Inspection.
NG -- CHECK ENGINE TO DETERMINE CAUSE OF LOW COMPRESSION
OK -- Continue to next step.
10. CHECK ECM TERMINAL VOLTAGE (POWER SOURCE OF FUEL INJECTOR)
(a) Disconnect the ECM connector.
(b) Turn the engine switch on (IG).
(c) Measure the voltage according to the value(s) in the table below.
Standard voltage:
(d) Reconnect the ECM connector.
NG -- GO TO FUEL INJECTOR CIRCUIT Fuel Injector Circuit
OK -- Continue to next step.
11. CHECK FUEL INJECTOR OF MISFIRING CYLINDER
(a) Check the injector injection (whether fuel volume is high or low, and whether injection pattern is poor) Testing and Inspection.
NG -- REPLACE FUEL INJECTOR ASSEMBLY Removal
OK -- Continue to next step.
12. CHECK AIR INDUCTION SYSTEM
(a) Check the air induction system for vacuum leakage.
OK:
No leakage from air induction system.
NG -- REPAIR OR REPLACE AIR INDUCTION SYSTEM
OK -- Continue to next step.
13. CHECK FUEL PRESSURE
(a) Check the fuel pressure Fuel System.
NG -- CHECK FUEL LINE
OK -- Continue to next step.
14. READ VALUE USING TECHSTREAM (COOLANT TEMP) P0171
NG -- REPLACE ENGINE COOLANT TEMPERATURE SENSOR Removal
OK -- Continue to next step.
15. READ VALUE USING TECHSTREAM (MAF) P0171
NG -- CHECK HARNESS AND CONNECTOR
OK -- Continue to next step.
16. CHECK VALVE TIMING P0011
OK -- CHECK HARNESS AND CONNECTOR
NG -- ADJUST VALVE TIMING Reassembly
17. CHECK AIR INDUCTION SYSTEM
(a) Check the air induction system for vacuum leakage.
OK:
No leakage from air induction system.
NG -- REPAIR OR REPLACE AIR INDUCTION SYSTEM
OK -- Continue to next step.
18. CHECK FUEL PRESSURE
(a) Check the fuel pressure Fuel System.
NG -- CHECK FUEL LINE
OK -- Continue to next step.
19. READ VALUE USING TECHSTREAM (COOLANT TEMP) P0171
NG -- REPLACE ENGINE COOLANT TEMPERATURE SENSOR Removal
OK -- Continue to next step.
20. READ VALUE USING TECHSTREAM (MAF) P0171
NG -- CHECK HARNESS AND CONNECTOR
OK -- Continue to next step.
21. CHECK VALVE TIMING P0011
NG -- ADJUST VALVE TIMING Reassembly
OK -- Continue to next step.
22. INSPECT SPARK PLUG
(a) Inspect the spark plug of the misfiring cylinder Testing and Inspection.
NG -- REPLACE SPARK PLUG Removal
OK -- Continue to next step.
23. CHECK FOR SPARK (SPARK TEST)
(a) Perform a spark test Testing and Inspection.
HINT
If the result of the spark test is normal, proceed to the next step.
NEXT -- Continue to next step.
24. CHECK CYLINDER COMPRESSION PRESSURE
(a) Measure the cylinder compression pressure of the misfiring cylinder On-Vehicle Inspection.
NG -- CHECK ENGINE TO DETERMINE CAUSE OF LOW COMPRESSION
OK -- Continue to next step.
25. CHECK ECM TERMINAL VOLTAGE (POWER SOURCE OF FUEL INJECTOR)
(a) Disconnect the ECM connector.
(b) Turn the engine switch on (IG).
(c) Measure the voltage according to the value(s) in the table below.
Standard voltage:
(d) Reconnect the ECM connector.
NG -- GO TO FUEL INJECTOR CIRCUIT Fuel Injector Circuit
OK -- Continue to next step.
26. CHECK FUEL INJECTOR OF MISFIRING CYLINDER
(a) Check the injector injection (whether fuel volume is high or low, and whether injection pattern is poor) Testing and Inspection.
NG -- REPLACE FUEL INJECTOR ASSEMBLY Removal
OK -- Continue to next step.
27. CHECK HARNESS AND CONNECTOR
(a) Check the connection and terminal contact pressure of connectors and wire harnesses between the mass air flow meter and ECM Electronic Circuit Inspection Procedure.
HINT
Repair any problems.
NEXT -- Continue to next step.
28. CHECK WHETHER DTC OUTPUT RECURS (DTC P0300, P0301, P0302, P0303, P0304, P0305 OR P0306)
(a) Connect the Techstream to the DLC3.
(b) Turn the engine switch on (IG).
(c) Turn the Techstream on
(d) Clear the DTCs Reading and Clearing Diagnostic Trouble Codes.
(e) Turn the engine switch off and wait for at least 30 seconds.
(f) Drive the vehicle in accordance with the driving pattern described in Confirmation Driving Pattern.
(g) Enter the following menus: Powertrain / Engine / Utility / All Readiness.
(h) Input DTC: P0300, P0301, P0302, P0303, P0304, P0305 or P0306.
(i) Check the DTC judgment result.
Result:
B -- END
A -- Continue to next step.
29. CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER - ECM) P0102
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.
30. REPLACE MASS AIR FLOW METER SUB- ASSEMBLY
(a) Replace the mass air flow meter assembly Removal.
HINT
If the result of the inspection performed in steps 15 and 20 indicated no problem, proceed to the next step without replacing the mass air flow meter assembly.
NEXT -- Continue to next step.
31. CONFIRM WHETHER MALFUNCTION HAS BEEN SUCCESSFULLY REPAIRED
(a) Connect the Techstream to the DLC3.
(b) Turn the engine switch on (IG).
(c) Turn the Techstream on
(d) Clear the DTCs Reading and Clearing Diagnostic Trouble Codes.
(e) Turn the engine switch off and wait for at least 30 seconds.
(f) Drive the vehicle in accordance with the driving pattern described in Confirmation Driving Pattern.
(g) Enter the following menus: Powertrain / Engine / Utility / All Readiness.
(h) Input DTC: P0300, P0301, P0302, P0303, P0304, P0305 or P0306.
(i) Check the DTC judgment result.
Result:
B -- END
A -- REPLACE ECM Removal
32. CHECK FUEL LINE
(a) Check the fuel lines for leaks or blockage.
NG -- REPAIR OR REPLACE FUEL LINE
OK -- REPLACE FUEL PUMP Removal