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: Procedure

1. Connect the Techstream to the DLC3.
2. Turn the ignition switch to ON.
3. Turn the Techstream on.
4. Enter the following menus: Powertrain / Engine / Trouble Codes.
5. Read the DTCs.

   HINT: 

   Write down the output DTCs.

   Result

   Result	Proceed to
   P0300, P0301, P0302, P0303 and/or P0304	A
   P0300, P0301, P0302, P0303 and/or P0304 and other DTCs	B

   HINT: 

   If any DTCs other than P0300, P0301, P0302, P0303 and P0304 are output, troubleshoot those DTCs first.

B → See step   39 

A: Go to next step 

1. Check the PCV hose connections.

   OK

   PCV hose is correctly connected and is not damaged.

NG → REPAIR OR REPLACE PCV HOSE 

OK: Go to next step 

1. Connect the Techstream to the DLC3.
2. Turn the ignition switch to ON.
3. Turn the Techstream on.
4. Enter the following menus: Powertrain / Engine / Data List / All Data / Misfire / Misfire RPM and Misfire Load.
5. 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: Go to next step 

1. Connect the Techstream to the DLC3.
2. Turn the ignition switch to ON.
3. Turn the Techstream on.
4. Enter the following menus: Powertrain / Engine / Data List / All Data / Catalyst OT MF F/C.
5. Read the value displayed on the Techstream.

   Result

   Data List	Techstream Display	Proceed to
   Catalyst OT MF F/C	Avail	A
   	Not Avl	B

B → See step   6 

A: Go to next step 

1. Connect the Techstream to the DLC3.
2. Turn the ignition switch to ON.
3. Turn the Techstream on.
4. Enter the following menus: Powertrain / Engine / Active Test / Prohibit the Catalyst OT Misfire prevent F/C.
5. Perform the Active Test.
   NOTE:

   When performing the Active Test, make sure the vehicle is stopped and the engine is either idling or being revved within 3000 RPM.

NEXT: Go to next step 

1. Connect the Techstream to the DLC3.
2. Turn the ignition switch to ON.
3. Turn the Techstream on.
4. Clear the DTCs, refer to DTC CHECK / CLEAR .
5. Enter the following menus: Powertrain / Engine / Data List / All Data / Cylinder #1 (to #4) Misfire Count.
6. Allow the engine to idle.
7. Read each value for Cylinder #1 (to #4) Misfire Count displayed on the Techstream. If no misfire counts occur in any cylinders, perform the following procedures:
   1. Move the shift lever in D.
   2. Check Cylinder #1 (to #4) Misfire Count.
   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 the Cylinder #1 (to #4) Misfire Count or the DTCs output on the Techstream.

      Result

      Result (Misfire Count)	Proceed to
      Most misfires occur in only 1 or 2 cylinders	A
      3 cylinders or more have equal misfire counts	B

      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 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 record of the Engine Run Time is below 120 seconds, the misfire may be detected immediately after the engine is started.

B → See step   19 

A: Go to next step 

1. Inspect the spark plug of the misfiring cylinder, refer to ON-VEHICLE INSPECTION - Step 2 .

NG → See step   40 

OK: Go to next step 

1. Perform a spark test, refer to INSTALLATION .
   WARNING:

   Always disconnect all the injector connectors.

   NOTE:

   Do not crank the engine for more than 2 seconds.

   OK

   Spark jumps across electrode gap.

NG → See step   36 

OK: Go to next step 

1. Measure the cylinder compression pressure of the misfiring cylinder, refer to ON-VEHICLE INSPECTION - Step 9 .

NG → CHECK ENGINE TO DETERMINE CAUSE OF LOW COMPRESSION 

OK: Go to next step 

NG → See step   41 

OK: Go to next step 

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR (FUEL INJECTOR - ECM) 

OK: Go to next step 

1. Check the injector injection (whether fuel volume is high or low, and whether injection pattern is poor), refer to INSPECTION .

NG → See step   42 

OK: Go to next step 

1. Check the intake system for vacuum leaks, refer to ON-VEHICLE INSPECTION .

   OK

   No leaks from intake system.

NG → REPAIR OR REPLACE INTAKE SYSTEM 

OK: Go to next step 

1. Check the intake air control valve for tumble control valve, refer to ON-VEHICLE INSPECTION - Step 3 .

NG → See step   43 

OK: Go to next step 

1. Check the fuel pressure, refer to ON-VEHICLE INSPECTION - Step 2 .

NG → See step   38 

OK: Go to next step 

NG → See step   44 

OK: Go to next step 

1. Connect the Techstream to the DLC3.
2. Turn the ignition switch to ON.
3. Turn the Techstream on.
4. Enter the following menus: Powertrain / Engine / Data List / All Data / MAF and Coolant Temp.
5. Allow the engine to idle until Coolant Temp reaches 75°C (167°F) or higher.
6. Read MAF with the engine speed at 3000 RPM.

   Standard

   Between 8.5 g/sec. and 12.5 g/sec. (shift lever: Neutral position, A/C: Off).

NG → See step   31 

OK: Go to next step 

OK → See step   31 

NG → See step   45 

1. Check the intake system for vacuum leaks, refer to ON-VEHICLE INSPECTION .

   OK

   No leaks from intake system.

NG → REPAIR OR REPLACE INTAKE SYSTEM 

OK: Go to next step 

1. Check the intake air control valve for tumble control valve, refer to ON-VEHICLE INSPECTION - Step 3 .

NG → See step   43 

OK: Go to next step 

1. Check the fuel pressure, refer to ON-VEHICLE INSPECTION - Step 2 .

NG → See step   38 

OK: Go to next step 

NG → See step   44 

OK: Go to next step 

1. Connect the Techstream to the DLC3.
2. Turn the ignition switch to ON.
3. Turn the Techstream on.
4. Enter the following menus: Powertrain / Engine / Data List / All Data / MAF and Coolant Temp.
5. Allow the engine to idle until Coolant Temp reaches 75°C (167°F) or higher.
6. Read MAF with the engine speed at 3000 RPM.

   Standard

   Between 8.5 g/sec. and 12.5 g/sec. (shift lever: Neutral position, A/C: Off).

NG → See step   31 

OK: Go to next step 

NG → See step   45 

OK: Go to next step 

1. Inspect the spark plug of the misfiring cylinder, refer to ON-VEHICLE INSPECTION - Step 2 .

NG → See step   40 

OK: Go to next step 

1. Perform a spark test, refer to INSTALLATION .
   WARNING:

   Always disconnect all the injector connectors.

   NOTE:

   Do not crank the engine for more than 2 seconds.

   OK

   Spark jumps across electrode gap.

NG → See step   36 

OK: Go to next step 

1. Measure the cylinder compression pressure of the misfiring cylinder, refer to ON-VEHICLE INSPECTION - Step 9 .

NG → CHECK ENGINE TO DETERMINE CAUSE OF LOW COMPRESSION 

OK: Go to next step 

NG → See step   41 

OK: Go to next step 

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR (FUEL INJECTOR - ECM) 

OK: Go to next step 

1. Check the injector injection (whether fuel volume is high or low, and whether injection pattern is poor), refer to INSPECTION .

NG → See step   42 

OK: Go to next step 

1. Check the connection and terminal contact pressure of connectors and wire harnesses between the mass air flow meter and ECM, refer to ELECTRONIC CIRCUIT INSPECTION PROCEDURE .

   HINT: 

   Repair any problems.

NEXT: Go to next step 

1. Connect the Techstream to the DLC3.
2. Turn the ignition switch to ON.
3. Turn the Techstream on.
4. Clear the DTCs, refer to DTC CHECK / CLEAR .
5. Turn the ignition switch off.
6. Turn the ignition switch to ON and turn the Techstream on.
7. Start the engine and warm it up.
8. Drive the vehicle in accordance with the driving pattern described in Confirmation Driving Pattern.
9. Enter the following menus: Powertrain / Engine / Utility / All Readiness.
10. Input the DTC: P0300, P0301, P0302, P0303 or P0304.
11. Check the DTC judgment result.
    RESULT
    
    

    Result	Proceed to
    ABNORMAL (DTC P0300, P0301, P0302, P0303 or P0304 is output)	A
    NORMAL (DTC is not output)	B

B → END 

A: Go to next step 

1. Disconnect the mass air flow meter connector.
2. Disconnect the ECM connector.
3. Measure the resistance according to the value(s) in the table below.

   Standard Resistance (Check for Open)

   Tester Connection	Condition	Specified Condition
   B10-5 (VG) - B50-11 (VG)	Always	Below 1 Ω
   B10-4 (E2G) - B50-5 (E2G)	Always	Below 1 Ω

   Standard Resistance (Check for Short)

   Tester Connection	Condition	Specified Condition
   B10-5 (VG) or B50-11 (VG) - Body ground	Always	10 kΩ or higher

4. Reconnect the mass air flow meter connector.
5. Reconnect the ECM connector.

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR (MASS AIR FLOW METER - ECM) 

OK: Go to next step 

1. Replace the mass air flow meter, refer to REMOVAL .

   HINT: 

   If the results of the inspections performed in steps 17 and 23 indicated no problem, proceed to the next step without replacing the mass air flow meter.

NEXT: Go to next step 

1. Connect the Techstream to the DLC3.
2. Turn the ignition switch to ON.
3. Turn the Techstream on.
4. Clear the DTCs, refer to DTC CHECK / CLEAR .
5. Turn the ignition switch off.
6. Turn the ignition switch to ON and turn the Techstream on.
7. Start the engine and warm it up.
8. Drive the vehicle in accordance with the driving pattern described in Confirmation Driving Pattern.
9. Enter the following menus: Powertrain / Engine / Utility / All Readiness.
10. Input the DTC: P0300, P0301, P0302, P0303 or P0304.
11. Check the DTC judgment result.
    RESULT
    
    

    Result	Proceed to
    NORMAL (DTC is not output)	A
    ABNORMAL (DTC P0300, P0301, P0302, P0303 or P0304 is output)	B

B → See step   46 

A → END 

1. Change the installed spark plug to a spark plug that functions normally.
2. Perform a spark test.
   WARNING:

   Always disconnect all injector connectors.

   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 electrode gap.

NG → See step   37 

OK → See step   40 

1. Change the ignition coil to a ignition coil that functions normally.
2. Perform a spark test.
   WARNING:

   Always disconnect all injector connectors.

   NOTE:

   Do not crank the engine for more than 2 seconds.

   1. Install the spark plug into 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 electrode gap.

NG → See step   46 

OK → See step   47 

1. Check the fuel lines for leaks or blockage.

NG → REPAIR OR REPLACE FUEL LINE 

OK → See step   48