P0303

1GR-FE ENGINE CONTROL: 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 enter the exhaust gas. High hydrocarbon concentration levels can cause an increase in exhaust emission 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 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

Text in Illustration

The ECM illuminates the MIL and stores 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 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)

Monitor Period of Emissions-related Misfire

Monitor Period of Catalyst-damaging Misfire (MIL Blinks)

TYPICAL MALFUNCTION THRESHOLDS

Monitor Period of Emissions-related Misfire

Monitor Period of Catalyst-damaging Misfire (MIL Blinks)

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 DTCs and freeze frame data.

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

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 No. 1 to No. 6) with the engine idling. 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, as 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.

9. 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 will be cleared.

10. Record the DTCs, freeze frame data and misfire counts.

11. Turn the ignition switch off and wait for at least 5 seconds.

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

MONITOR RESULT

Refer to Checking Monitor Status Mode 6 Data.

WIRING DIAGRAM

Refer to DTC P0102 P0102.

INSPECTION PROCEDURE

NOTICE:
Inspect the fuses for circuits related to this system before performing the following 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 can be considered to be a possible cause of the problem:
(1) There was an insufficient amount of fuel in the tank.
(2) Improper fuel was used.
(3) The spark plugs have been contaminated.
* After finishing repairs, check the misfire counts of the cylinders (Cylinder #1 Misfire Count to Cylinder #6 Misfire Count).
* Be sure to confirm that no misfiring cylinder DTCs are stored again by conducting the confirmation driving pattern after finishing repairs.
* For 6 and 8 cylinder engines, the ECM intentionally does not store the specific misfiring cylinder DTCs at high engine speeds. If misfires occur only at high engine speeds, only DTC P0300 is stored.
In the event of DTC P0300 being output, perform the following operations:
(1) Clear the DTCs Reading and Clearing Diagnostic Trouble Codes.
(2) Start the engine and conduct the confirmation driving pattern.
(3) Read the misfiring rates of each cylinder or the DTCs using the Techstream.
(4) Repair the cylinders that have a high misfiring rate or are indicated by the DTCs.
(5) 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 +/-20%, the air-fuel ratio may be Rich (-20% or less) or Lean (+20% or more).
* When Coolant Temp in the freeze frame data is below 75°C (167°F), the misfire 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 ignition switch to ON.

(c) Turn the Techstream on.

(d) Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.

(e) Read DTCs.

HINT
Write down the 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.

OK:

PCV hose is correctly connected 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 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) Enter the following menus: Powertrain / Engine and ECT / Data List / Cylinder #1 Misfire Count, #2, #3, #4, #5 and #6.

(b) Read the values for Cylinder #1 Misfire Count to Cylinder #6 Misfire Count displayed on the Techstream. If no misfire counts occur in any cylinders, perform the following procedure:

* Start the engine and let it idle.

* Move the shift lever to D.

* Check Cylinder #1 Misfire Count to Cylinder #6 Misfire Count.

* If misfire counts are still not displayed, perform the steps below.

(c) 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.

(d) Read Cylinder #1 Misfire Count to Cylinder #6 Misfire Count 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 Engine Run Time is below 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 Testing and Inspection.

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

8. CHECK FOR SPARKS AND IGNITION

(a) Perform a spark test Testing and Inspection.

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 -- REPLACE SPARK PLUG WITH NORMAL ONE 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 TERMINAL VOLTAGE (POWER SOURCE OF FUEL INJECTOR OF MISFIRING CYLINDER)

(a) Disconnect the fuel injector assembly connector (of the misfiring cylinder).

(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 -- REPAIR OR REPLACE HARNESS OR CONNECTOR (NO. 1 INTEGRATION RELAY (IG2) - FUEL INJECTOR)
OK -- Continue to next step.

11. CHECK HARNESS AND CONNECTOR (ECM - FUEL INJECTOR OF MISFIRING CYLINDER)

(a) Disconnect the fuel injector assembly connector (of the misfiring cylinder).

(b) Disconnect the ECM connector.

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

Standard Resistance:

(d) Reconnect the fuel injector assembly connector.

(e) Reconnect the ECM connector.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (FUEL INJECTOR - ECM)
OK -- Continue to next step.

12. CHECK FUEL INJECTOR OF MISFIRING CYLINDER

(a) Check the fuel injector resistance Testing and Inspection.

(b) 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 Intake System.

OK:

No leakage from air induction system.

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

14. CHECK FUEL PRESSURE

(a) Check the fuel pressure Fuel System.

NG -- REPAIR OR REPLACE FUEL PUMP, PRESSURE REGULATOR, FUEL PIPE LINE AND FILTER
OK -- Continue to next step.

15. READ VALUE USING TECHSTREAM (COOLANT TEMP) P0171

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

16. READ VALUE USING TECHSTREAM (MAF)

(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 / All Data / MAF, Coolant Temp and Engine Speed.

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

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

Standard:

Between 13.8 g/sec. and 17.3 g/sec. (shift lever: N; A/C: Off).

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

17. CHECK VALVE TIMING P0011

OK -- CHECK HARNESS AND CONNECTOR

NG -- ADJUST VALVE TIMING Reassembly

18. CHECK AIR INDUCTION SYSTEM

(a) Check the air induction system for vacuum leakage Intake System.

OK:

No leakage from air induction system.

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

19. CHECK FUEL PRESSURE

(a) Check the fuel pressure Fuel System.

NG -- REPAIR OR REPLACE FUEL PUMP, PRESSURE REGULATOR, FUEL PIPE LINE AND FILTER
OK -- Continue to next step.

20. READ VALUE USING TECHSTREAM (COOLANT TEMP) P0171

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

21. READ VALUE USING TECHSTREAM (MAF)

(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 / All Data / MAF, Coolant Temp and Engine Speed.

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

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

Standard:

Between 13.8 g/sec. and 17.3 g/sec. (shift lever: N; A/C: Off).

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

22. CHECK VALVE TIMING P0011

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

23. INSPECT SPARK PLUG

(a) Inspect the spark plug Testing and Inspection.

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

24. CHECK FOR SPARKS AND IGNITION

(a) Perform a spark test Testing and Inspection.

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 -- REPLACE SPARK PLUG WITH NORMAL ONE AND CHECK SPARK OF MISFIRING CYLINDER
OK -- Continue to next step.

25. 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.

26. CHECK TERMINAL VOLTAGE (POWER SOURCE OF FUEL INJECTOR OF MISFIRING CYLINDER)

(a) Disconnect the fuel injector assembly connector (of the misfiring cylinder).

(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 -- REPAIR OR REPLACE HARNESS OR CONNECTOR (NO. 1 INTEGRATION RELAY (IG2) - FUEL INJECTOR)
OK -- Continue to next step.

27. CHECK HARNESS AND CONNECTOR (ECM - FUEL INJECTOR OF MISFIRING CYLINDER)

(a) Disconnect the fuel injector assembly connector (of the misfiring cylinder).

(b) Disconnect the ECM connector.

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

Standard Resistance:

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

31. CHECK HARNESS AND CONNECTOR (MASS AIR FLOW - 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:

(d) Reconnect the mass air flow meter connector.

(e) Reconnect the ECM connector.

NG -- REPLACE HARNESS OR CONNECTOR (MASS AIR FLOW - ECM)
OK -- Continue to next step.

32. REPLACE MASS AIR FLOW METER

(a) Replace the mass air flow meter Removal.

HINT
If the results of the inspections performed in steps 16 and 21 indicated no problem, proceed to the next step without replacing the mass air flow meter.

NEXT -- Continue to next step.

33. CONFIRM WHETHER MALFUNCTION HAS BEEN SUCCESSFULLY REPAIRED

(a) Connect the Techstream to the DLC3.

(b) Turn the ignition switch to ON.

(c) Turn the Techstream on.

(d) Clear DTCs Reading and Clearing Diagnostic Trouble Codes.

(e) Turn the ignition switch off and wait for at least 30 seconds.

(f) Turn the ignition switch to ON.

(g) Turn the Techstream on.

(h) Start the engine.

(i) Warm up the engine.

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

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

(l) Input the DTC: P0300, P0301, P0302, P0303, 0304, P0305 or P0306.

(m) Check the DTC judgment result.

Result

B -- REPLACE ECM Removal

A -- END

34. 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:
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 connectors.

(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 IGNITION COIL WITH NORMAL ONE AND CHECK SPARK OF MISFIRING CYLINDER

OK -- REPLACE SPARK PLUG Removal

35. 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:
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 Removal