Part 1
1UR-FSE ENGINE CONTROL SYSTEM: SFI SYSTEM: P0300-P0308: Random / Multiple Cylinder Misfire Detected
P0308 - Cylinder 8 Misfire Detected
DESCRIPTION
When the engine misfires, high concentrations of hydrocarbons (HC) enter the exhaust gas. Extremely high hydrocarbons concentration levels can cause an increase in exhaust emission levels. 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 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 misfire count (approximately 20 to 50 misfires per 1000 crankshaft revolutions) occurs once.
- After the first 1000 crankshaft revolutions, an excessive misfire count (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 damage, is detected (2 trip detection logic):
- In every 200 crankshaft revolutions at a high engine speed, the threshold misfire percentage is recorded once.
- In every 200 crankshaft revolutions at a normal engine speed, the threshold misfire percentage is recorded 3 times.
MONITOR STRATEGY
TYPICAL ENABLING CONDITIONS
Misfire
Monitor Period of Emission-Related Misfire
Monitor Period of Catalyst-Damaging Misfire (MIL Blinks)
TYPICAL MALFUNCTION THRESHOLDS
Monitor Period of Emission-Related Misfire
Monitor Period of Catalyst-Damaging Misfire (MIL Blinks)
MONITOR RESULT
Refer to Checking Monitor Status Mode 6 Data.
WIRING DIAGRAM
Mass air flow meter circuit: Refer to P0102 P0102.
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. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can be helpful in determining whether the vehicle was running or stopped, whether the engine was warmed up or not, whether the air fuel ratio was lean or rich, as well as other data recorded at the time of a malfunction.
- 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 8 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 DTCs Reading and Clearing Diagnostic Trouble Codes.
(2) Start the engine and conduct the confirmation driving pattern.
(3) Read the misfire count of each cylinder or DTC(s) using the Techstream.
(4) Repair the cylinder(s) that has a high misfiring count 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 to be detected.
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 the 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 (HOSE CONNECTIONS)
OK:
PCV hose is connected correctly 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).
(c) Turn the Techstream on.
(d) Enter the following menus: Powertrain / Engine / Data List / Catalyst OT MF F/C.
(e) Read the value displayed on the Techstream.
Result:
B -- CHECK MISFIRE COUNT OF PORT INJECTION
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 / Active Test / Prohibit the Catalyst OT Misfire prevent F/C.
(e) Perform the Active Test.
NOTICE:
When performing the Active Test, make sure that the vehicle is stopped and either idling or being revved within 3000 rpm.
NEXT -- Continue to next step.
6. 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 Reading and Clearing Diagnostic Trouble Codes.
(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 / 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 shift lever to D.
(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
A -- Continue to next step.
7. 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 Reading and Clearing Diagnostic Trouble Codes.
(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: Enter the following menus: Powertrain / Engine / Data List / Cylinder #1 Misfire Count Cylinder #8 Misfire Count.
If no misfire counts occur for any of the cylinders, perform the following procedure: (Procedure "B")
(1) Move the shift lever to D.
(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 ASSEMBLY (FOR DIRECT INJECTION) Components
8. 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 Reading and Clearing Diagnostic Trouble Codes.
(e) Enter the following menus: Powertrain / Engine / Data List / 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 ASSEMBLY (FOR DIRECT INJECTION MALFUNCTIONING CYLINDER) Components
C -- CHECK INTAKE SYSTEM
B -- CHECK SPARK PLUG
A -- CHECK FOR INTERMITTENT PROBLEMS Check For Intermittent Problems
9. 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 Reading and Clearing Diagnostic Trouble Codes.
(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 / 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 shift lever to D.
(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 INJECTOR ASSEMBLY (MALFUNCTIONING CYLINDER) Components
B -- CHECK INTAKE SYSTEM
A -- Continue to next step.
10. CHECK SPARK PLUG
(a) Inspect the spark plug Testing and Inspection.
NG -- REPLACE SPARK PLUG Removal
OK -- Continue to next step.
11. CHECK FOR SPARK AND IGNITION
(a) Remove the ignition coil assemblies.
(b) Remove the spark plugs.
(c) Install the spark plug to the ignition coil.
(d) Disconnect the 2 fuel delivery pipe connectors.
(e) Disconnect the 4 connectors with wire harness locks from the 2 injector drivers.
(f) Attach the spark plug assembly to the cylinder head cover.
(g) Crank the engine for less than 2 seconds and check the spark.
OK:
Sparks jump across the electrode gap.
(h) Reconnect the 4 connectors with wire harness locks to the 2 injector drivers.
(i) Reconnect the 2 fuel delivery pipe connectors.
(j) Reinstall the spark plugs.
(k) Reinstall the ignition coil assemblies.
NG -- CHANGE TO NORMAL SPARK PLUG AND CHECK SPARK OF MISFIRING CYLINDER
OK -- Continue to next step.
12. CHECK CYLINDER COMPRESSION PRESSURE (MALFUNCTIONING 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.
13. CHECK INTAKE SYSTEM
(a) Check the intake system for vacuum leaks.
OK:
No leaks in the intake system.
NG -- REPAIR OR REPLACE INTAKE SYSTEM
OK -- Continue to next step.
14. CHECK VALVE TIMING P0016
NG -- ADJUST VALVE TIMING
OK -- Continue to next step.
15. CHECK FUEL PRESSURE (LOW PRESSURE SIDE)
(a) Check the fuel pressure (low pressure side) Fuel System.
NG -- CHECK FUEL PUMP OPERATION
OK -- Continue to next step.
16. 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 / 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 Components
OK -- Continue to next step.