P0303
2TR-FE ENGINE CONTROL: SFI SYSTEM: P0300-P0304: 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
DESCRIPTION
Text in Illustration
When the engine misfires, high concentrations of hydrocarbons enter the exhaust gas. High hydrocarbon concentration levels can cause an increase in exhaust emissions 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 rate. 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 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, 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 stores a DTC when either one of the following conditions, which could cause catalyst deterioration, is detected (2 trip detection logic).
* Within the first 1000 crankshaft revolutions after the engine starts, an excessive number of misfires (approximately 20 to 50 misfires per 1000 crankshaft revolutions) occurs once.
* An excessive number of misfires (approximately 20 to 50 misfires per 1000 crankshaft revolutions) occurs a total of 4 times.
The ECM flashes the MIL and stores a DTC when either one of the following conditions, which could cause damage to the three-way catalytic converter, is detected (2 trip detection logic).
* At a high engine speed, catalyst-damaging misfire, which is monitored every 200 crankshaft revolutions, occurs once.
* At a normal engine speed, catalyst-damaging misfire, which is monitored every 200 crankshaft revolutions, occurs 3 times.
HINT
If catalyst-damaging misfire occurs, the ECM informs the driver by flashing the MIL.
MONITOR STRATEGY
TYPICAL ENABLING CONDITIONS
Misfire
Monitor Period of Emissions-related Misfire
Monitor Period of Catalyst-damaging Misfire (MIL Blinks)
TYPICAL MALFUNCTION THRESHOLDS
Emissions-related Misfire
Catalyst-damaging Misfire (MIL Blinks)
MONITOR RESULT
Refer to Checking Monitor Status Mode 6 Data.
WIRING DIAGRAM
CONFIRMATION DRIVING PATTERN
1. Connect the Techstream to the DLC3.
2. Turn the ignition switch to ON.
3. Turn the Techstream on.
4. Record the DTC(s) and freeze frame data.
5. Using the Techstream, switch the ECM from normal mode to check mode Scan Tool Testing and Procedures.
6. Read the misfire count of each cylinder (Cylinder #1 to #4) with the engine idling. If any misfire count is displayed, skip the following confirmation driving pattern.
7. If no misfire counts are displayed, drive the vehicle several times at the engine speed and engine load recorded in the freeze frame data.
HINT
- In order to detect misfire DTCs, drive the vehicle at the engine speed and engine load recorded in the freeze frame data for the time specified in the table below.
8. Check whether misfires have occurred by checking DTCs and freeze frame data.
HINT
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 are cleared.
9. Record the DTCs, freeze frame data and misfire count.
10. Turn the ignition switch off and wait for at least 5 seconds.
INSPECTION PROCEDURE
HINT
- If any DTCs other than misfire DTCs are output, troubleshoot those DTCs first.
- Read freeze frame data using the Techstream. 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 reproduced, one of the following factors can be considered to be a possible cause of the problem:
(1) The fuel level is low.
(2) Improper fuel was 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 any cylinder (Cylinder #1, #2, #3 and #4).
- Be sure to confirm that no misfiring cylinder DTCs are stored again by conducting the confirmation driving pattern after the repairs.
- When either Short FT #1 or Long FT #1 values in the freeze frame data are not within 20% of the central value, 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 misfires occurred only while warming up the engine.
PROCEDURE
1. CHECK FOR ANY OTHER DTCS OUTPUT (IN ADDITION TO MISFIRE CODES)
(a) Connect the Techstream to the DLC3.
(b) Turn the ignition switch to ON.
(c) Turn the Techstream on.
(d) Enter the following menus: Powertrain / Engine and ECT / DTC.
(e) Read the DTCs.
Result
HINT
If any DTCs other than P0300, P0301, P0302, P0303 and P0304 are output, troubleshoot those DTCs first.
B -- GO TO DTC CHART Engine Control System - SFI System
A -- Continue to next step.
2. CHECK PCV HOSE CONNECTIONS
(a) Check the PCV hose connections Testing and 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 ignition switch to ON and turn the Techstream on.
(c) Enter the following menus: Powertrain / Engine and ECT / 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
(a) Connect the Techstream to the DLC3.
(b) Turn the ignition switch to ON and turn the Techstream on.
(c) Enter the following menus: Powertrain / Engine and ECT / 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 ignition switch to ON and turn the Techstream on.
(c) Enter the following menus: Powertrain / Engine and ECT / 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 ignition switch to ON.
(c) Turn the Techstream on.
(d) Enter the following menus: Powertrain / Engine and ECT / Data List / Cylinder #1 (to #4) Misfire Count.
(e) Drive the vehicle at the engine speed and engine load noted in the "Read Value Using Techstream (Misfire RPM and Misfire Load)" procedure above.
(f) Read Cylinder #1 (to #4) Misfire Count or the DTCs displayed on the Techstream.
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's 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's 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
A -- Continue to next step.
7. CHECK SPARK PLUG
(a) Check the spark plug of the misfiring cylinder Testing and Inspection.
NG -- REPLACE SPARK PLUG Removal
OK -- Continue to next step.
8. CHECK FOR SPARK AND IGNITION
(a) Perform a spark test Testing and Inspection.
NG -- REPLACE SPARK PLUG WITH NORMAL ONE AND CHECK SPARK OF MISFIRING CYLINDER
OK -- Continue to next step.
9. CHECK CYLINDER COMPRESSION PRESSURE OF MISFIRING CYLINDER
(a) Measure the cylinder compression pressure of the misfiring cylinder Engine.
NG -- CHECK ENGINE TO DETERMINE CAUSE OF LOW COMPRESSION
OK -- Continue to next step.
10. CHECK FUEL INJECTOR ASSEMBLY (POWER SOURCE)
(a) Disconnect the fuel injector assembly connector.
(b) Measure the voltage according to the value(s) in the table below.
Standard Voltage:
Text in Illustration
(c) Reconnect the fuel injector assembly connector.
NG -- CHECK FUEL INJECTOR CIRCUIT
OK -- Continue to next step.
11. CHECK HARNESS AND CONNECTOR (FUEL INJECTOR ASSEMBLY - ECM)
(a) Disconnect the fuel injector assembly connector.
(b) Disconnect the ECM connector.
(c) Measure the resistance according to the value(s) in the table below.
Standard Resistance (Check for Open):
Standard Resistance (Check for Short):
(d) Reconnect the fuel injector assembly connector.
(e) Reconnect the ECM connector.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (FUEL INJECTOR ASSEMBLY - ECM)
OK -- Continue to next step.
12. INSPECT ECM TERMINAL OF MISFIRING CYLINDER (#10, #20, #30 AND/OR #40 VOLTAGE)
(a) Disconnect the ECM connector.
(b) Measure the voltage according to the value(s) in the table below.
Standard Voltage:
Text in Illustration
(c) Reconnect the ECM connector.
NG -- CHECK HARNESS AND CONNECTOR (ECM - BODY GROUND)
OK -- Continue to next step.
13. CHECK FUEL INJECTOR OF MISFIRING CYLINDER
(a) Check the fuel 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.
14. CHECK INTAKE SYSTEM
(a) Check the intake system for vacuum leakage Testing and Inspection.
OK:
No leakage from intake system.
NG -- REPAIR OR REPLACE INTAKE SYSTEM
OK -- Continue to next step.
15. CHECK FUEL PRESSURE
(a) Check the fuel pressure Testing and Inspection.
NG -- CHECK FUEL LINE
OK -- Continue to next step.
16. READ VALUE USING TECHSTREAM (COOLANT TEMP)
(a) Connect the Techstream to the DLC3.
(b) Turn the ignition switch to ON.
(c) Turn the Techstream on.
(d) Enter the following menus: Powertrain / Engine and ECT / Data List / Coolant Temp.
(e) Read 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 95°C (167°F and 203°F).
NG -- REPLACE ENGINE COOLANT TEMPERATURE SENSOR Removal
OK -- Continue to next step.
17. INSPECT MASS AIR FLOW METER
(a) Inspect the mass air flow meter On-Vehicle Inspection.
NG -- REPLACE MASS AIR FLOW METER Removal
OK -- Continue to next step.
18. ADJUST VALVE TIMING
HINT
There are no marks on the cylinder head to align for the purpose of checking valve timing. Valve timing can only be inspected by aligning the colored plates on the timing chain with the marks on the pulleys. It may be necessary to remove and reinstall the chain to align the timing marks Installation.
NEXT -- Continue to next step.
19. CHECK WHETHER DTC OUTPUT RECURS (DTC P0300, P0301, P0302, P0303 AND/OR P0304)
(a) Connect the Techstream to the DLC3.
(b) Turn the ignition switch to ON.
(c) Turn the Techstream on.
(d) Clear the DTCs DTC Check / Clear.
(e) Start the engine and warm it up.
(f) Switch the ECM from normal mode to check mode using the Techstream.
(g) Run the engine at an engine speed of 1000 rpm for 3 minutes.
(h) Enter the following menus: Powertrain / Engine and ECT / DTC.
(i) Read the DTCs.
Result
B -- REPLACE ECM Removal
A -- SYSTEM IS OK
20. CHECK INTAKE SYSTEM
(a) Check the intake system for vacuum leakage Testing and Inspection.
OK:
No leakage from intake system.
NG -- REPAIR OR REPLACE INTAKE SYSTEM
OK -- Continue to next step.
21. CHECK FUEL PRESSURE
(a) Check the fuel pressure Testing and Inspection.
NG -- CHECK FUEL LINE
OK -- Continue to next step.
22. READ VALUE USING TECHSTREAM (COOLANT TEMP)
(a) Connect the Techstream to the DLC3.
(b) Turn the ignition switch to ON.
(c) Turn the Techstream on.
(d) Enter the following menus: Powertrain / Engine and ECT / Data List / Coolant Temp.
(e) Read 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 95°C (167°F and 203°F).
NG -- REPLACE ENGINE COOLANT TEMPERATURE SENSOR Removal
OK -- Continue to next step.
23. INSPECT MASS AIR FLOW METER
(a) Inspect the mass air flow meter On-Vehicle Inspection.
NG -- REPLACE MASS AIR FLOW METER Removal
OK -- Continue to next step.
24. ADJUST VALVE TIMING
HINT
There are no marks on the cylinder head to align for the purpose of checking valve timing. Valve timing can only be inspected by aligning the colored plates on the timing chain with the marks on the pulleys. It may be necessary to remove and reinstall the chain to align the timing marks Installation.
NEXT -- Continue to next step.
25. CHECK WHETHER DTC OUTPUT RECURS (DTC P0300, P0301, P0302, P0303 AND/OR P0304)
(a) Connect the Techstream to the DLC3.
(b) Turn the ignition switch to ON.
(c) Turn the Techstream on.
(d) Clear the DTCs DTC Check / Clear.
(e) Start the engine and warm it up.
(f) Switch the ECM from normal mode to check mode using the Techstream.
(g) Run the engine at an engine speed of 1000 rpm for 3 minutes.
(h) Enter the following menus: Powertrain / Engine and ECT / DTC.
(i) Read the DTCs.
Result
B -- CHECK SPARK PLUG
A -- SYSTEM IS OK
26. CHECK SPARK PLUG
(a) Check the spark plug of the misfiring cylinder Testing and Inspection.
NG -- REPLACE SPARK PLUG Removal
OK -- Continue to next step.
27. CHECK FOR SPARK AND IGNITION (SPARK TEST)
(a) Perform a spark test Testing and Inspection.
NG -- REPLACE SPARK PLUG WITH NORMAL ONE AND CHECK SPARK OF MISFIRING CYLINDER
OK -- Continue to next step.
28. CHECK CYLINDER COMPRESSION PRESSURE OF MISFIRING CYLINDER
(a) Measure the cylinder compression pressure of the misfiring cylinder Engine.
NG -- CHECK ENGINE TO DETERMINE CAUSE OF LOW COMPRESSION
OK -- Continue to next step.
29. CHECK FUEL INJECTOR ASSEMBLY (POWER SOURCE)
(a) Disconnect the fuel injector assembly connector.
(b) Measure the voltage according to the value(s) in the table below.
Standard Voltage:
Text in Illustration
(c) Reconnect the fuel injector assembly connector.
NG -- CHECK FUEL INJECTOR CIRCUIT
OK -- Continue to next step.
30. CHECK HARNESS AND CONNECTOR (FUEL INJECTOR ASSEMBLY - ECM)
(a) Disconnect the fuel injector assembly connector.
(b) Disconnect the ECM connector.
(c) Measure the resistance according to the value(s) in the table below.
Standard Resistance (Check for Open):
Standard Resistance (Check for Short):
(d) Reconnect the fuel injector assembly connector.
(e) Reconnect the ECM connector.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (FUEL INJECTOR ASSEMBLY - ECM)
OK -- Continue to next step.
31. INSPECT ECM TERMINAL OF MISFIRING CYLINDER (#10, #20, #30 AND/OR #40 VOLTAGE)
(a) Disconnect the ECM connector.
(b) Measure the voltage according to the value(s) in the table below.
Standard Voltage:
Text in Illustration
(c) Reconnect the ECM connector.
NG -- CHECK HARNESS AND CONNECTOR (ECM - BODY GROUND)
OK -- Continue to next step.
32. CHECK FUEL INJECTOR OF MISFIRING CYLINDER
(a) Check the fuel 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 -- REPLACE ECM Removal
33. REPLACE SPARK PLUG WITH NORMAL ONE AND CHECK SPARK OF MISFIRING CYLINDER
(a) Replace the installed spark plug with a spark plug that functions normally.
(b) Perform a spark test.
CAUTION:
During the test, disconnect all the injector connectors.
NOTICE:
Do not crank the engine for more than 2 seconds.
(1) Install the spark plug to the ignition coil.
(2) Disconnect the 4 fuel injector connectors.
(3) Touch the spark plug assembly to the cylinder head.
(4) Crank the engine for less than 2 seconds and check for sparks.
OK:
Sparks jump across electrode gap.
NG -- REPLACE IGNITION COIL WITH NORMAL ONE AND CHECK SPARK OF MISFIRING CYLINDER
OK -- REPLACE SPARK PLUG Removal
34. REPLACE IGNITION COIL WITH NORMAL ONE AND CHECK SPARK OF MISFIRING CYLINDER
(a) Replace the ignition coil with an ignition coil that functions normally.
(b) Perform a spark test.
CAUTION:
During the test, disconnect all the injector connectors.
NOTICE:
Do not crank the engine for more than 2 seconds.
(1) Install the spark plug to the ignition coil and connect the ignition coil connector.
(2) Disconnect the 4 fuel injector connectors.
(3) Touch the spark plug assembly to the cylinder head.
(4) Crank the engine for less than 2 seconds and check for sparks.
OK:
Sparks jump across electrode gap.
NG -- REPLACE ECM Removal
OK -- REPLACE IGNITION COIL Removal
35. CHECK HARNESS AND CONNECTOR (ECM - BODY GROUND)
(a) Disconnect the ECM connector.
(b) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (ECM - BODY GROUND)
OK -- REPLACE FUEL INJECTOR ASSEMBLY Removal
36. CHECK FUEL LINE
(a) Check the fuel lines for leaks or blockage Testing and Inspection.
OK:
No leaks or blockage.
NG -- REPAIR OR REPLACE FUEL LINE
OK -- REPLACE FUEL PUMP Removal