P0304
2GR-FSE 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 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 VVT sensor and the Crankshaft Position (CKP) sensor. The VVT 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 10 to 50 misfires per 1000 crankshaft revolutions) occurs once.
- After the first 1000 crankshaft revolutions, an excessive misfiring rate (approximately 10 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 speed, the threshold misfiring percentage is recorded once.
- In every 200 crankshaft revolutions at a normal engine speed, 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. Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure) Reading and Clearing Diagnostic Trouble Codes.
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 in an idling condition. If any misfire count is displayed, skip the following confirmation driving pattern.
8. Drive the vehicle several times with the conditions, such as engine speed and engine load, 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 confirm the Misfire and Misfire Load in the Date List.
9. Check whether misfires have occurred by checking DTCs and freeze frame data.
HINT
Do not turn the engine switch off until the output 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 DTC P0102 P0102.
Refer to DTC P0201 P0201.
Refer to DTC P0351 P0351.
Refer to DTC P1276 P1276.
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 Freeze Frame Data.
- 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 to #6 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 cylinder engines, the ECM intentionally does not set the specific misfiring cylinder DTCs at high engine RPM. 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 DTC Reading and Clearing Diagnostic Trouble Codes.
(2) Start the engine and conduct the confirmation driving pattern.
(3) Read the misfire rate of each cylinder or DTC(s) using the Techstream.
(4) Repair the cylinder(s) that has a high misfire 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 more).
- When the Coolant Temp in the freeze frame data is less than 75°C (167°F), the misfire has occurred only while warming up the engine.
- An extremely imbalanced drive wheel which causes body vibration may cause misfire DTC 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) and turn the Techstream on.
(c) Enter the following menus: Powertrain / Engine / Trouble Codes.
(d) 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 CONNECTIONS
(a) Check the PCV hose connections On-Vehicle Inspection.
OK:
PCV valve and hose are connected correctly and are 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 / Misfire RPM and Misfire Load.
(d) Read and note the Misfire RPM and Misfire Load (engine 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) 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 -- 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) 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 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) Start the engine.
(c) Turn the Techstream on.
(d) Enter the following menus: Powertrain / Engine / Active Test / Control the Injection Way / Port / Gas Misfire / Cylinder #1 Misfire Count to Cylinder #6 Misfire Count.
(e) 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:
B -- CHECK MISFIRE COUNT OF DIRECT INJECTION
A -- Continue to next step.
7. CHECK MISFIRE COUNT OF DIRECT INJECTION
(a) Connect the Techstream to the DLC3.
(b) Start the engine.
(c) Turn the Techstream on.
(d) Enter the following menus: Powertrain / Engine / Active Test / Control the Injection Way / Direct / Gas Misfire / Cylinder #1 Misfire Count to Cylinder #6 Misfire Count.
(e) 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:
B -- CHECK AIR INDUCTION SYSTEM
C -- REPLACE FUEL INJECTOR FOR PORT INJECTION (MISFIRING CYLINDER) Removal
D -- CHECK FUEL PRESSURE (LOW PRESSURE SIDE)
A -- Continue to next step.
8. 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.
9. 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.
10. CHECK CYLINDER COMPRESSION PRESSURE (MALFUNCTION CYLINDER)
(a) Measure the cylinder compression pressure of the misfiring cylinder On-Vehicle Inspection.
NG -- REPAIR OR REPLACE ENGINE TO DETERMINE CAUSE OF LOW COMPRESSION
OK -- REPLACE ECM Removal
11. CHECK AIR INDUCTION SYSTEM
(a) Check the air induction system for vacuum leaks.
OK:
No leaks in air induction system.
NG -- REPAIR OR REPLACE AIR INDUCTION SYSTEM
OK -- Continue to next step.
12. 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 / MAF and Coolant Temp.
(e) Read the 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 100°C (167°F and 212°F).
NG -- REPLACE ENGINE COOLANT TEMPERATURE SENSOR Removal
OK -- Continue to next step.
13. READ VALUE USING TECHSTREAM (MAF)
(a) Connect the Techstream to the DLC3.
(b) Start the engine.
(c) Turn the Techstream on.
(d) Enter the following menus: Powertrain / Engine / Data List / MAF and Coolant Temp.
(e) Allow the engine to idle until the Coolant Temp reaches 75°C (167°F) or more.
(f) Read MAF with the engine speed of 3000 rpm.
Standard:
Between 13.0 gm/sec and 14.0 gm/sec (shift lever: N, A/C: off).
NG -- CHECK HARNESS AND CONNECTOR
OK -- Continue to next step.
14. CHECK VALVE TIMING
(a) Remove the cylinder head cover RH and LH.
(b) Turn the crankshaft pulley, and align its groove with the timing mark "0" of the timing chain cover.
(c) Check that the timing mark of each camshaft timing gear is aligned with the timing mark of each bearing cap as shown in the illustration.
If not, turn the crankshaft 1 revolution (360°), then align the marks as above.
OK:
Timing marks on camshaft timing gears are aligned as shown in the illustration.
(d) Reinstall the cylinder head cover.
NG -- ADJUST VALVE TIMING
OK -- REPLACE ECM Removal
15. CHECK FUEL PRESSURE (LOW PRESSURE SIDE)
(a) Check the fuel pressure (low pressure side) Testing and Inspection.
NG -- CHECK FUEL PUMP OPERATION (FOR LOW PRESSURE)
OK -- REPLACE FUEL INJECTOR FOR PORT INJECTION (MISFIRING CYLINDER)
16. CHECK FUEL PUMP OPERATION (FOR LOW PRESSURE)
(a) Check the fuel pump operation Testing and Inspection.
NG -- REPLACE FUEL PUMP (FOR LOW PRESSURE) Removal
OK -- CHECK AND REPLACE FUEL SYSTEM (PRESSURE REGULATOR, PIPE LINE AND FILTER)
17. CHECK MISFIRE COUNT OF DIRECT INJECTION
(a) Connect the Techstream to the DLC3.
(b) Start the engine.
(c) Turn the Techstream on.
(d) Enter the following menus: Powertrain / Engine / Active Test / Control the Injection Way / Direct / Gas Misfire / Cylinder #1 Misfire Count to Cylinder #6 Misfire Count.
(e) 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:
B -- CHECK MISFIRE COUNT
A -- REPLACE FUEL INJECTOR FOR DIRECT INJECTION (MISFIRING CYLINDER)
18. CHECK MISFIRE COUNT
(a) Connect the Techstream to the DLC3.
(b) Start the engine and turn the Techstream on.
(c) Clear DTCs Reading and Clearing Diagnostic Trouble Codes.
(d) Enter the following menus: Powertrain / Engine / Data List / Misfire RPM, Misfire Load, Cylinder #1 to #6 Misfire Count and Injection Way.
(e) Drive the vehicle with Misfire RPM and Misfire Load.
(f) Monitor all of the misfire count values or DTCs and Injection Way displayed on the Techstream.
Result:
B -- INSPECT SPARK PLUG
C -- CHECK AIR INDUCTION SYSTEM
D -- REPLACE FUEL INJECTOR FOR DIRECT INJECTION (MALFUNCTION CYLINDER INJECTOR) Removal
A -- CHECK FOR INTERMITTENT PROBLEMS Check for Intermittent Problems
19. 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.
20. 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.
21. CHECK CYLINDER COMPRESSION PRESSURE (MISFIRE CYLINDER)
(a) Measure the cylinder compression pressure of the misfiring cylinder On-Vehicle Inspection.
NG -- CHECK ENGINE TO DETERMINE CAUSE OF LOW COMPRESSION
OK -- REPLACE ECM Removal
22. CHECK AIR INDUCTION SYSTEM
(a) Check the air induction system for vacuum leaks.
OK:
No leaks from air induction system.
NG -- REPAIR OR REPLACE AIR INDUCTION SYSTEM
OK -- Continue to next step.
23. 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 / MAF and Coolant Temp.
(e) Read the 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 100°C (167°F and 212°F).
NG -- REPLACE ENGINE COOLANT TEMPERATURE SENSOR Removal
OK -- Continue to next step.
24. READ VALUE USING TECHSTREAM (MAF)
(a) Connect the Techstream to the DLC3.
(b) Start the engine.
(c) Turn the Techstream on.
(d) Enter the following menus: Powertrain / Engine / Data List / MAF and Coolant Temp.
(e) Allow the engine to idle until the Coolant Temp reaches 75°C (167°F) or more.
(f) Read MAF with the engine speed of 3000 rpm.
Standard:
Between 13.0 gm/sec and 14.0 gm/sec (shift lever: N, A/C: off).
NG -- CHECK HARNESS AND CONNECTOR
OK -- Continue to next step.
25. CHECK VALVE TIMING
(a) Remove the cylinder head cover RH and LH.
(b) Turn the crankshaft pulley, and align its groove with the timing mark "0" of the timing chain cover.
(c) Check that the timing mark of each camshaft timing gear is aligned with the timing mark of each bearing cap as shown in the illustration.
If not, turn the crankshaft 1 revolution (360°), then align the marks as above.
OK:
Timing marks on camshaft timing gears are aligned as shown in the illustration.
(d) Reinstall the cylinder head cover.
NG -- ADJUST VALVE TIMING
OK -- REPLACE ECM Removal
26. CHECK HARNESS AND CONNECTOR
(a) Check the connection and terminal contact pressure of connectors and wire harness between the mass air flow meter sub-assembly and ECM Electronic Circuit Inspection Procedure.
HINT
Repair any problems.
NEXT -- Continue to next step.
27. 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) 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 / Utility / All Readiness.
(j) Input the DTC: P0300, P0301, P0302, P0303, P0304, P0305 or P0306.
(k) Check the DTC judgment result.
Result:
B -- END
A -- Continue to next step.
28. CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER - ECM)
(a) Disconnect the E29 MAF meter connector.
(b) Disconnect the E5 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 ECM connector.
(e) Reconnect the MAF meter connector.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.
29. REPLACE MASS AIR FLOW METER
(a) Replace the mass air flow meter Removal.
HINT
If the result of the inspection performed in steps 13 and 24 indicated no problem, proceed to the next step without replacing the mass air flow meter.
NEXT -- Continue to next step.
30. 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) 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 / Utility / All Readiness.
(j) Input the DTC: P0300, P0301, P0302, P0303, P0304, P0305 or P0306.
(k) Check the DTC judgment result.
Result:
B -- END
A -- REPLACE ECM Removal