P0306

1UR-FSE ENGINE CONTROL SYSTEM: SFI SYSTEM: P0300: 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

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. 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 rate. 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 exceeds the threshold levels and may cause emission deterioration, the ECM illuminates the MIL and sets a DTC.






If DTCs that indicate misfires are set for different cylinders, 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.

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.
- After the first 1000 crankshaft revolutions, an excessive misfiring rate (approximately 20 to 60 misfires per 1000 crankshaft revolutions) occurs 4 times in sequential crankshaft revolutions.

The ECM flashes the MIL and sets a DTC when either one of the following conditions, which could cause the Three-Way Catalytic Converter (TWC) damage, is detected (2 trip detection logic):

- In every 200 crankshaft revolutions at a high engine rpm, the threshold misfiring percentage is recorded once.
- In every 200 crankshaft revolutions at a normal engine rpm, the threshold misfiring percentage is recorded 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-damage-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 Using the Techstream, switch the ECM from normal mode to check mode Check Mode Procedure.
6 Read the misfire counts of each cylinder Cylinder #1 Misfire Count to Cylinder #8 Misfire Count with the engine in an idling condition. If any misfire count is displayed, skip the following confirmation driving pattern.
7 Drive the vehicle several times with the conditions, such as engine rpm and engine load, shown in Misfire RPM and Misfire Load in the Data List.
HINT: 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.





8 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.

9 Record the DTC(s), freeze frame data and misfire counts.
10 Turn the engine 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 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 is 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 #8 Misfire Count).
- Be sure to confirm that no misfiring cylinder DTCs are set again by conducting the confirmation driving pattern after finishing repairs.
- For 6 and 8 cylinder engines, the ECM intentionally does not set the specific misfiring cylinder DTCs at high engine RPM. If misfires occur only in high engine RPM areas, only DTC P0300 is set.
In the event of DTC P0300 being present, perform the following operations:
1 Clear the DTC DTC Check / Clear.
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 +/-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 less than 75°C (167°F), the misfire have occurred only while warming up the engine.
- An extremely imbalanced drive wheel, which causes body vibration, may cause misfire DTCs detection.

PROCEDURE

1. CHECK ANY OTHER DTC OUTPUT (IN ADDITION TO MISFIRE DTCS)
(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, P0306, P0307 and P0308 are output, troubleshoot those DTCs first.

B -- GO TO DTC CHART SFI System
A -- Continue to next step.

2. 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 / 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.

3. CHECK VENTILATION HOSE (HOSE CONNECTIONS)
OK:
Ventilation hose is connected correctly and is not damaged.
NG -- REPAIR OR REPLACE VENTILATION HOSE
OK -- Continue to next step.

4. CHECK MISFIRE COUNT OF PORT INJECTION
(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 / Active Test / Control the Injection Way / Port. (Procedure "A")
(f) Allow the engine to idle.
(g) Monitor all of the misfire count values that are displayed on the Techstream: Powertrain / Engine / Data List / Misfire / Cylinder #1 Misfire Count to Cylinder #8 Misfire Count.
If no misfire counts occur for any of the cylinders, perform the following procedure: (Procedure "B")
(1) Move the gear selector lever to the D position.
(2) Repeat procedure "A" to "B" above.
(3) Monitor all of the misfire count values that are displayed on the Techstream.
Result:






B -- CHECK MISFIRE COUNT OF DIRECT INJECTION
A -- Continue to next step.

5. CHECK MISFIRE COUNT OF DIRECT INJECTION
(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 / Active Test / Control the Injection Way / Direct. (Procedure "A")
(f) Allow the engine to idle.
(g) Monitor all of the misfire count values that are displayed on the Techstream: Powertrain / Engine / Data List / Misfire / Cylinder #1 Misfire Count to Cylinder #8 Misfire Count.
If no misfire counts occur for any of the cylinders, perform the following procedure: (Procedure "B")
(1) Move the gear selector lever to the D position.
(2) Repeat procedure "A" to "B" above.
(3) Monitor all of the misfire count values that are displayed on the Techstream.
Result:






D -- CHECK FUEL PRESSURE (LOW PRESSURE SIDE)
C -- REPLACE FUEL INJECTOR FOR PORT INJECTION (MISFIRING CYLINDER)
B -- CHECK AIR INDUCTION SYSTEM
A -- Continue to next step.

6. CHECK SPARK PLUG
(a) Remove the ignition coil and the spark plug of the misfiring cylinder.
(b) Measure the spark plug electrode gap Testing and Inspection.
NG -- REPLACE SPARK PLUG
OK -- Continue to next step.

7. CHECK FOR SPARK AND IGNITION
(a) Disconnect the injector connectors, in order to prevent the engine from starting.
(b) Install the spark plug to the ignition coil.
(c) Attach the spark plug assembly to the cylinder head cover.
(d) Crank the engine for less than 2 seconds and check the spark.
OK:
Sparks jump across the electrode gap.
(e) Reconnect the injector connectors.
NG -- CHANGE TO NORMAL SPARK PLUG AND CHECK SPARK OF MISFIRING CYLINDER
OK -- Continue to next step.

8. CHECK CYLINDER COMPRESSION PRESSURE (MALFUNCTIONING CYLINDER)
(a) Measure the cylinder compression pressure of the misfiring cylinder On-Vehicle Inspection.
OK -- REPLACE ECM
NG -- CHECK ENGINE TO DETERMINE CAUSE OF LOW COMPRESSION
9. 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 each injector connector.
NOTE:
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 connector.
(3) Ground the spark plug.
(4) Check if sparks occur while the engine is being cranked.
OK:
Sparks jump across the electrode gap.
NG -- REPLACE IGNITION COIL ASSEMBLY THEN CONFIRM THAT THERE IS NO MISFIRE
OK -- REPLACE SPARK PLUG
10. 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.

11. READ VALUE USING TECHSTREAM (COOLANT TEMP)
(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 / All Data / Coolant Temp.
(e) Read the Data List 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
OK -- Continue to next step.

12. INSPECT MASS AIR FLOW METER (BANK 1 AND BANK 2)
(a) Inspect the mass air flow meter On-Vehicle Inspection.
NG -- REPLACE MASS AIR FLOW METER
OK -- Continue to next step.

13. CHECK VALVE TIMING P0016
NG -- ADJUST VALVE TIMING
OK -- REPLACE ECM
14. CHECK FUEL PRESSURE (LOW PRESSURE SIDE)
(a) Check the fuel pressure (low pressure side) Testing and Inspection.
OK -- REPLACE FUEL INJECTOR FOR PORT INJECTION
NG -- Continue to next step.

15. CHECK FUEL PUMP OPERATION
(a) Check the fuel pump operation Fuel Pump.
OK -- CHECK AND REPLACE FUEL SYSTEM (PRESSURE REGULATOR, PIPE LINE AND FILTER)
NG -- REPLACE FUEL PUMP
16. CHECK MISFIRE COUNT OF DIRECT INJECTION
(a) Connect the Techstream to the DLC3.
(b) Turn the engine switch on (IG).
(c) Turn the Techstream ON.
(d) Clear DTCs.
(e) Enter the following menus: Powertrain / Engine / Active Test / Control the Injection Way / Direct. (Procedure "A")
(f) Allow the engine to idle.
(g) Monitor all of the misfire count values that are displayed on the Techstream: Powertrain / Engine / Data List / Misfire / Cylinder #1 Misfire Count to Cylinder #8 Misfire Count.
If no misfire counts occur for any of the cylinders, perform the following procedure: (Procedure "B")
(1) Move the gear selector lever to the D position.
(2) Repeat procedure "A" to "B" above.
(3) Monitor all of the misfire count values that are displayed on the Techstream.
Result:






C -- CHECK MISFIRE COUNT
B -- CHECK FUEL PRESSURE SENSOR
A -- REPLACE FUEL INJECTOR FOR DIRECT INJECTION (MISFIRING CYLINDER)
17. CHECK FUEL PRESSURE SENSOR
(a) Connect the Techstream to the DLC3.
(b) Turn the engine switch on (IG) and turn the Techstream ON.
(c) Start the engine.
(d) Enter the following menus: Powertrain / Engine / Data List / All Data / Fuel Press.
(e) While revving the engine, check that the fuel pressure fluctuates.
Standard:
Idling
3 to 5 MPa
2500 rpm (No load)
6 to 10 MPa
HINT: The A/C switch and all accessory switches should be OFF, and the transmission gear selector lever should be in the N or P position, and the engine should be fully warmed up.

NG -- REPAIR OR REPLACE FUEL SYSTEM FOR HIGH PRESSURE

(a) Check the fuel pressure Testing and Inspection.

NG -- REPLACE FUEL PUMP ASSEMBLY (for Low Pressure)
OK -- Continue to next step.

18. READ VALUE USING TECHSTREAM
(a) Connect the Techstream to the DLC3.
(b) Start the engine and turn the Techstream ON.
(c) Enter the following menus: Powertrain / Engine / Active Test / Control the Injection way / Direct.
HINT: The A/C switch and all accessory switches should be OFF, and the transmission gear selector lever should be in the N or P position, and the engine should be fully warmed up.
(d) Read the value: Data List / A/F Control System / Short FT #1, Long FT #1, Short FT #2, Long FT #2 and Fuel Pump Duty (D4).
Result:






D -- REPLACE FUEL INJECTOR FOR DIRECT INJECTION (MALFUNCTIONING CYLINDER INJECTOR)
C -- REPLACE ECM
B -- REPLACE FUEL PRESSURE SENSOR
A -- REPLACE FUEL PRESSURE SENSOR
19. CHECK 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 / Data List / All Data / Misfire RPM, Misfire Load, Cylinder #1 Misfire Count to Cylinder #8 Misfire Count and Injection Way.
(f) Drive the vehicle with Misfire RPM and Misfire Load.
(g) Monitor all of the misfire count values or DTCs and Injection Way displayed on the Techstream.
Result:






E -- CHECK FUEL PRESSURE SENSOR
D -- REPLACE FUEL INJECTOR FOR DIRECT INJECTION (MALFUNCTIONING CYLINDER INJECTOR)
C -- CHECK AIR INDUCTION SYSTEM
B -- CHECK SPARK PLUG
A -- CHECK FOR INTERMITTENT PROBLEMS