P0303

1UR-FE ENGINE CONTROL: SFI SYSTEM: P0300-P0308: 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

DTC P0307 - Cylinder 7 Misfire Detected

DTC P0308 - Cylinder 8 Misfire Detected

DESCRIPTION





Text in Illustration





When the engine misfires, high concentrations of hydrocarbons (HC) enter the exhaust gas. Extremely high HC concentration levels can cause increases in exhaust emissions levels. High concentrations of HC can also cause increases in the Three-way Catalytic Converter (TWC) temperature, which may cause damage to the Three-way Catalytic Converter (TWC). To prevent these increases 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 (TWC) reaches the point of thermal degradation, the MIL blinks. 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 as when the crankshaft rotation speed variations exceed predetermined thresholds.

If the misfire rate exceeds the threshold level, the ECM illuminates the MIL and stores a DTC.





When multiple DTCs for misfiring cylinders are 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 immediately when either one of the following conditions, which could cause catalyst deterioration, is detected (2 trip detection logic).

- Within the first 1000 crankshaft revolutions of the engine starting, an excessive misfiring rate (approximately 40 to 60 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 immediately when either one of the following conditions, which could cause Three-way Catalytic Converter (TWC) damage, is detected. Also, the ECM stores a DTC when either one of the following conditions is detected (2 trip detection logic).

- At a high engine speed, a sufficient amount of misfires to damage the catalyst occurring within 200 crankshaft revolutions is detected once.

- At a normal engine speed, a sufficient amount of misfires to damage the catalyst occurring within 200 crankshaft revolutions is detected 3 times.

MONITOR STRATEGY





TYPICAL ENABLING CONDITIONS

Misfire





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.

WIRING DIAGRAM













CONFIRMATION DRIVING PATTERN

- Connect the Techstream to the DLC3.

- Turn the engine switch on (IG).

- Turn the Techstream on.

- Record the DTC(s) and freeze frame data.

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

- Using the Techstream, switch the ECM from normal mode to check mode Check Mode Procedure.

- Read the misfire counts of each cylinder (cylinder No. 1 to No. 8) with the engine idling. If any 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.

HINT
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.





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

HINT
Do not turn the engine 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 engine switch off and wait for at least 30 seconds.

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

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 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 may be a cause of the problem:
* The fuel level is low.
* Improper fuel is being used.
* The spark plugs are dirty.
- After finishing repairs, check that no misfires occur in each cylinder (cylinder No. 1, No. 2, No. 3, No. 4, No. 5, No. 6, No. 7 and No. 8).
- Be sure to confirm that no misfiring cylinder DTCs are stored again by conducting the confirmation driving pattern after the repairs.
- For 6 and 8 cylinder engines, the ECM intentionally does not store the specific misfiring cylinder DTCs at high engine speed. If misfires only occur during high engine speed driving, only DTC P0300 is stored.
- In the event of DTC P0300 being output, perform the following operations:
* Clear the DTCs DTC Check / Clear.
* Start the engine and conduct the confirmation driving pattern.
* Read the misfiring rates of each cylinder or the DTCs using the Techstream.
* Repair the cylinders that have a high misfiring rate or are indicated by the DTCs.
* After finishing repairs, conduct the confirmation driving pattern again in order to verify that DTC P0300 is not stored.
- 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 more).
- When Coolant Temp in the freeze frame data is below 75°C (167°F), the misfires may 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 FOR ANY OTHER DTCS 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 and ECT / Trouble Codes.

(e) Read DTCs.

Result





HINT
If any DTCs other than P0300, P0301, P0302, P0303, P0304, P0305, P0306, P0307 and P0308 are output, troubleshoot those DTCs first.

B -- GO TO DTC CHART 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 connected correctly and is not damaged.

NG -- REPAIR OR REPLACE PCV HOSE Removal
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).

(c) Turn the Techstream on.

(d) Enter the following menus: Powertrain / Engine and ECT / Data List / All Data / Misfire RPM and Misfire Load.

(e) 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 engine switch on (IG).

(c) Turn the Techstream on.

(d) Enter the following menus: Powertrain / Engine and ECT / Data List / Catalyst OT MF F/C.

(e) 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).

(c) Turn the Techstream on.

(d) Enter the following menus: Powertrain / Engine and ECT / Active Test / Prohibit the Catalyst OT Misfire prevent F/C.

(e) 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) Clear DTCs DTC Check / Clear.

(e) Enter the following menus: Powertrain / Engine and ECT / Data List / All Data / Cylinder #1 Misfire Rate, #2, #3, #4, #5, #6, #7 and #8.

(f) Allow the engine to idle.

(g) Read each value for CYL #1 to #8 (Cylinder #1 Misfire Rate to #8) displayed on the Techstream. If no misfire counts occur in any cylinders, perform the following procedures:

(1) Move the shift lever to D.

(2) Check CYL #1 to #8 (Cylinder #1 Misfire Rate to #8).

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

Procedure A: Drive the vehicle while satisfying the Misfire RPM and Misfire Load values noted in the "Read Value Using Techstream (Misfire RPM and Misfire Load)" procedure above.

Procedure B: Read CYL #1 to #8 (Cylinder #1 Misfire Rate to #8) or the DTCs output 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 less than 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 SPARKS AND IGNITION

(a) Perform a spark test Removal.

CAUTION:
Always disconnect all the injector connectors.

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

OK:

Spark jumps across electrode gap.

NG -- CHANGE TO NORMAL SPARK PLUG AND CHECK SPARK OF MISFIRING CYLINDER
OK -- Continue to next step.

9. CHECK CYLINDER COMPRESSION PRESSURE

(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) Fuel Injector Circuit

NG -- GO TO FUEL INJECTOR CIRCUIT Fuel Injector Circuit
OK -- Continue to next step.

11. CHECK HARNESS AND CONNECTOR Fuel Injector Circuit

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.

12. CHECK FUEL INJECTOR ASSEMBLY 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.

13. CHECK AIR INDUCTION SYSTEM

(a) Check the air induction system for vacuum leakage Testing and Inspection.

OK:

No leakage in air induction system.

NG -- REPAIR OR REPLACE AIR INDUCTION SYSTEM
OK -- Continue to next step.

14. CHECK FUEL PRESSURE

(a) Check the fuel pressure Testing and Inspection.

NG -- CHECK FUEL LINE
OK -- Continue to next step.

15. READ VALUE USING TECHSTREAM (COOLANT TEMP) P0171

NG -- REPLACE ENGINE COOLANT TEMPERATURE SENSOR
OK -- Continue to next step.

16. READ VALUE USING TECHSTREAM (MAF)

(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 and ECT / Data List / All Data / MAF and Coolant Temp.

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

(f) Read MAF with the engine speed at 3000 rpm.

Standard:

Between 18.3 g/sec. and 25.8 g/sec. (shift lever: N; A/C: Off).

NG -- CHECK HARNESS AND CONNECTOR
OK -- Continue to next step.

17. CHECK VALVE TIMING P0011

NG -- ADJUST VALVE TIMING Reassembly
OK -- Continue to next step.

18. PERFORM ACTIVE TEST USING TECHSTREAM (CONTROL THE EGR STEP POSITION)

(a) Connect the Techstream to the DLC3.

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

HINT
- When performing the Active Test, make sure the shift lever is in P or N.
- The A/C switch and all accessory switches should be off.
(c) Turn the Techstream on.

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

(e) Confirm that Throttle Idle Position is ON and check the engine idling condition and the value of MAP in the Data List while performing the Active Test.

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

OK:

MAP and idling condition change in response to EGR step position as follows.

Standard:





NG -- INSPECT EGR VALVE ASSEMBLY

OK -- CHECK HARNESS AND CONNECTOR

19. INSPECT EGR VALVE ASSEMBLY

(a) Remove the EGR valve assembly Removal.

(b) Check if the EGR valve is stuck open.

OK:

EGR valve is tightly closed.

NG -- REPLACE EGR VALVE ASSEMBLY Removal

OK -- CHECK HARNESS AND CONNECTOR

20. CHECK AIR INDUCTION SYSTEM

(a) Check the air induction system for vacuum leakage Testing and Inspection.

OK:

No leakage in air induction system.

NG -- REPAIR OR REPLACE AIR INDUCTION 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) P0171

NG -- REPLACE ENGINE COOLANT TEMPERATURE SENSOR
OK -- Continue to next step.

23. READ VALUE USING TECHSTREAM (MAF)

(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 and ECT / Data List / All Data / MAF and Coolant Temp.

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

(f) Read MAF with the engine speed at 3000 rpm.

Standard:

Between 18.3 g/sec. and 25.8 g/sec. (shift lever: N; A/C: Off).

NG -- CHECK HARNESS AND CONNECTOR
OK -- Continue to next step.

24. CHECK VALVE TIMING P0011

NG -- ADJUST VALVE TIMING Reassembly
OK -- Continue to next step.

25. PERFORM ACTIVE TEST USING TECHSTREAM (CONTROL THE EGR STEP POSITION)

(a) Connect the Techstream to the DLC3.

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

HINT
- When performing the Active Test, make sure the shift lever is in P or N.
- The A/C switch and all accessory switches should be off.
(c) Turn the Techstream on.

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

(e) Confirm that Throttle Idle Position is ON and check the engine idling condition and the value of MAP in the Data List while performing the Active Test.

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

OK:

MAP and idling condition change in response to EGR step position as follows.

Standard:





NG -- INSPECT EGR VALVE ASSEMBLY

OK -- INSPECT SPARK PLUG

26. INSPECT EGR VALVE ASSEMBLY

(a) Remove the EGR valve assembly Removal.

(b) Check if the EGR valve is stuck open.

OK:

EGR valve is tightly closed.

NG -- REPLACE EGR VALVE ASSEMBLY Removal
OK -- Continue to next step.

27. INSPECT SPARK PLUG

(a) Inspect the spark plug of the misfiring cylinder Removal.

NG -- REPLACE SPARK PLUG Removal
OK -- Continue to next step.

28. CHECK FOR SPARKS AND IGNITION

(a) Perform a spark test Removal.

CAUTION:
Always disconnect all injector connectors.

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

OK:

Sparks jump across electrode gap.

NG -- CHANGE TO NORMAL SPARK PLUG AND CHECK SPARK OF MISFIRING CYLINDER
OK -- Continue to next step.

29. CHECK CYLINDER COMPRESSION PRESSURE

(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.

30. CHECK FUEL INJECTOR ASSEMBLY (POWER SOURCE) Fuel Injector Circuit

NG -- GO TO FUEL INJECTOR CIRCUIT Fuel Injector Circuit
OK -- Continue to next step.

31. CHECK HARNESS AND CONNECTOR (FUEL INJECTOR - ECM) Fuel Injector Circuit

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.

32. CHECK FUEL INJECTOR ASSEMBLY 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.

33. 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.

34. CHECK WHETHER DTC OUTPUT RECURS

(a) Connect the Techstream to the DLC3.

(b) Turn the engine switch on (IG).

(c) Turn the Techstream on.

(d) Clear the DTCs DTC Check / Clear.

(e) Turn the engine switch off.

(f) Turn the engine switch on (IG) and turn the Techstream on.

(g) Start the engine and warm it up.

(h) Drive the vehicle in accordance with the driving pattern described in Confirmation Driving Pattern.

(i) Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.

(j) Input the DTC: P0300, P0301, P0302, P0303, P0304, P0305, P0306, P0307 or P0308.

(k) Check the DTC judgment result.

Result





B -- END
A -- Continue to next step.

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

(a) Disconnect the mass air flow meter connector.

(b) Disconnect the ECM connector.

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

Standard Resistance:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.

36. REPLACE MASS AIR FLOW METER ASSEMBLY

(a) Replace the mass air flow meter assembly Removal.

HINT
If the results of the inspections performed in steps 16 and 23 indicated no problem, proceed to the next step without replacing the mass air flow meter assembly.

NEXT -- Continue to next step.

37. 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 DTC Check / Clear.

(e) Turn the engine switch off.

(f) Turn the engine switch on (IG) and turn the Techstream on.

(g) Start the engine and warm it up.

(h) Drive the vehicle in accordance with the driving pattern described in Confirmation Driving Pattern.

(i) Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.

(j) Input the DTC: P0300, P0301, P0302, P0303, P0304, P0305, P0306, P0307 or P0308.

(k) Check the DTC judgment result.

Result





B -- REPLACE ECM Removal

A -- END

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

(a) Change the installed spark plug to a spark plug that functions normally.

(b) 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 to the ignition coil and connect the ignition coil connector.

(2) Disconnect the injector connectors.

(3) Ground the spark plug.

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

OK:

Sparks jump across electrode gap.

NG -- CHANGE TO NORMAL IGNITION COIL ASSEMBLY AND CHECK SPARK OF MISFIRING CYLINDER

OK -- REPLACE SPARK PLUG Removal

39. CHANGE TO NORMAL IGNITION COIL ASSEMBLY AND CHECK SPARK OF MISFIRING CYLINDER

(a) Change the ignition coil assembly to an ignition coil assembly that functions normally.

(b) Perform a spark test.

CAUTION:
Always disconnect all fuel 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 fuel injector connectors.

(3) Ground the spark plug.

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

OK:

Sparks jump across electrode gap.

NG -- REPLACE ECM Removal

OK -- REPLACE IGNITION COIL ASSEMBLY Removal

40. CHECK FUEL LINE

(a) Check the fuel lines for leaks or blockage.

NG -- REPAIR OR REPLACE FUEL LINE

OK -- REPLACE FUEL PUMP