GSIC - Global Service Information Center

### 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

## for Preparation Click here

## DESCRIPTION

When the engine misfires, high concentrations of hydrocarbons (HC) enter the exhaust gas. Extremely high HC concentration levels can cause 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 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 could cause emissions deterioration, the ECM illuminates the MIL and set a DTC.

DTC No. | DTC Detection Condition | Trouble Area

P0300

Simultaneous misfiring of several cylinder detected
(2 trip detection logic)

1. Open or short in engine wire harness
2. Connector connection
3. Vacuum hose connections
4. Ignition system
5. Injector
6. Fuel pressure
7. Mass Air Flow (MAF) meter
8. Engine Coolant Temperature (ECT) sensor
9. Compression pressure
10. Valve clearance
11. Valve timing
12. PCV valve and hose
13. PCV hose connections
14. Air induction system
15. ECM

P0301
P0302
P0303
P0304
P0305
P0306

Misfiring of specific cylinder detected
(2 trip detection logic)

1. Open or short in engine wire harness
2. Connector connection
3. Vacuum hose connections
4. Ignition system
5. Injector
6. Fuel pressure
7. MAF meter
8. ECT sensor
9. Compression pressure
10. Valve clearance
11. Valve timing
12. PCV valve and hose
13. PCV hose connections
14. Air induction system
15. ECM

When DTCs for misfiring cylinders are randomly set, 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.
Reference: Inspect using an oscilloscope.
With the engine idling, check the waveform between terminals #10 to #60 and E1 of the ECM connectors.

Item | Content
Tester Connection | CH 1: #10 to #60 - E01 CH 2: INJF - E01
Tool Setting | 20 V/DIV., 100 or 1 msec./DIV.
Condition | Idling

HINT:

  The correct waveform is as shown.

## 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).

1. Within the first 1,000 crankshaft revolutions of the engine starting, an excessive misfiring rate (approximately 20 to 50 misfires per 1,000 crankshaft revolutions) occurs ones.
2. After the first 1,000 crankshaft revolutions, an excessive misfiring rate (approximately 20 to 60 misfires per 1,000 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 TWC damage, is detected (2 trip detection logic).

1. For every 200 crankshaft revolutions at a high engine rpm, the threshold misfiring percentage is recorded once.
2. For every 200 crankshaft revolutions at a normal engine rpm, the threshold misfiring percentage is recorded 3 times.

## WIRING DIAGRAM

## CONFIRMATION DRIVING PATTERN

1. Connect the intelligent tester the DLC3.
2. Turn the ignition switch ON and turn the tester ON.
3. Record the DTC(s) and freeze frame data.
4. Using the tester, change the ECM from normal mode to check mode (Click here).
5. Read the misfire counts of each cylinder (CYL #10 to #60) with the engine in an idling condition. If any misfire count is displayed, skip the following confirmation driving pattern.
6. Drive the vehicle several times with the engine 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 derive the vehicle for the period of time shown in the table below, with the Misfire RPM and Misfire Load in the Data List.

   Engine Speed | Time
   Idling | 3.5 minutes or more
   1,000 rpm | 3 minutes or more
   2,000 rpm | 1.5 minutes or more
   3,000 rpm | 1 minute or more

7. Check whether misfires have occurred by checking DTCs and freeze frame data.

   HINT:
     Do not turn the ignition 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.
8. Record the DTC(s), freeze frame data and misfire counts.
9. Turn the ignition switch OFF and wait for at least 5 seconds.

## INSPECTION PROCEDURE

HINT:

1. If any DTCs other than the misfire DTCs are output, troubleshoot those DTCs first.
2. Read freeze frame data using the intelligent tester. Freeze frame data records the engine conditions when a malfunction is detected. When troubleshooting, freeze frame data can help determine if the vehicle was running or stopped, 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.
3. If the misfire does not recur when the vehicle is brought to the workshop, reproduce the conditions stored in the freeze frame data.
4. The misfire still cannot be reproduced even though the conditions stored in the freeze frame data have been duplicated, one of the following factors may be a possible cause of the problem:

1. The fuel in the fuel tank is low.
2. Improper fuel is used.
3. The spark plugs have been contaminated.
4. The problem is complex.

5. After finishing repairs, check the misfire counts of the cylinders (CYL #10, #20, #30, #40, #50 and #60).
6. Be sure to confirm that no misfiring cylinder DTCs are set again by conducting the confirmation driving pattern, after repair.
7. For 6 and 8 cylinder engines, the ECM intentionally does not set the specific misfiring cylinder DTCs at a high engine rpm. If misfires occur only at a high engine rpm, only DTC P0300 is set.
   In the event that DTC P0300 is present, perform the following operations:

1. Clear the DTC (Click here).
2. Start the engine and conduct the confirmation driving pattern.
3. Read the misfiring rates of each cylinder or DTC using the tester.
4. Repair each cylinder 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.

8. When 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).
9. When the Coolant Temp value in the freeze frame data is less than 75°C (167°F), the misfires have occurred only while warming up the engine.

1.CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO MISFIRE DTCS)

1. Connect the intelligent tester to the DLC3.

1. Turn the ignition switch ON and turn the tester ON.

1. Turn the tester ON.

1. Enter the following menus: Powertrain / Engine and ECT / DTC.

1. Read DTCs.

   Result:

     Display (DTC output) | Proceed to
     P0300, P0301, P0302, P0303, P0304, P0305 or P0306 | A
     P0300, P0301, P0302, P0303, P0304, P0305 or P0306 and other DTCs | B

   HINT:
     If any DTCs other than P0300, P0301, P0302, P0303, P0304, P0305 and P0306 are output, troubleshoot those DTCs first.

| B |

GO TO RELEVANT DTC CHART

A |

2.READ DATA LIST (MISFIRE RPM AND MISFIRE LOAD)

1. Connect the intelligent tester to the DLC3.

1. Turn the ignition switch ON and turn the tester ON.

1. Enter the following menu items: Powertrain / Engine and ECT / Data List / Misfire RPM and Misfire Load.

1. Read and note the Misfire RPM (engine speed) and Misfire Load (engine load) values.

   HINT:
     The Misfire RPM and Misfire Load indicate the vehicle conditions under which the misfire occurred.

NEXT |

3.CHECK PCV HOSE CONNECTIONS

OK:
  PCV hose is connected correctly and is not damaged.

| NG |

REPAIR OR REPLACE PCV HOSE

OK |

4.CHECK MISFIRE COUNT (CYL #10, #20, #30, #40, #50 AND #60)

1. Connect the intelligent tester to the DLC3.

1. Turn the ignition switch ON and turn the tester ON.

1. Clear DTCs (Click here).

1. Enter the following menus: Powertrain / Engine and ECT / Data List / Cylinder #10 (to #60) Misfire Rate. *1

1. Allow the engine to idle.

1. Read each value of Cylinder #10 to #60 displayed on the tester. If no misfire counts occur in any cylinders, perform the following operations. *2

   1. Move the shift lever to the drive position.

   2. Repeat steps *1 and *2 above.

   3. Check the Cylinder #10 to #60.

   4. If misfire counts are still not displayed, perform steps *3 and *4 and then check the misfire counts again.

1. Drive the vehicle with the Misfire RPM and Misfire Load noted in step 2. *3

1. Read the Cylinder #10 to #60 or DTCs displayed on the tester. *4

   Result:

     High Misfire Rate Cylinder | Proceed to
     1 or 2 cylinders have misfire counts | A
     3 cylinders or more have misfire counts | B

| B |

Go to step 13

A |

5.CHECK SPARK PLUG

1. Remove the ignition coil and the spark plug of the misfiring cylinder.

1. Measure the spark plug electrode gap.

   Standard:
     Between 1.0 and 1.1 mm (0.039 and 0.043 in.)

1. Check the electrode for carbon deposits.

   Recommended spark plug:

     Manufacturer | Product
     DENSO | K20HR-U11
     NGK | LFR6C-11

   NOTICE:
     If the electrode gap is larger than the standard, replace the spark plug. Do not adjust the electrode gap.

| NG |

REPLACE SPARK PLUG

OK |

6.CHECK FOR SPARKS AND IGNITION

1. Disconnect the injector connectors, in order to prevent the engine from starting.

1. Install the spark plug to the ignition coil.

1. Attach the spark plug assembly to the cylinder head cover.

1. Crank the engine for less than 2 seconds and check the spark.

   OK:
     Sparks jump across electrode gap.

| NG |

Go to step 8

OK |

7.CHECK CYLINDER COMPRESSION PRESSURE OF MISFIRING CYLINDER

1. Measure the cylinder compression pressure of the misfiring cylinder.

| OK |

Go to step 9

NG |

REPAIR OR REPLACE MALFUNCTION PARTS

8.CHANGE NORMAL SPARK PLUG AND CHECK SPARK OF MISFIRING CYLINDER

1. Change the installed spark plug to a spark plug that functions normally.

1. Perform a spark test.

   CAUTION:
     Always disconnect each injector connector.

   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 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 |

REPLACE IGNITION COIL ASSEMBLY THEN CONFIRM THAT THERE IS NO MISFIRE

OK |

REPLACE SPARK PLUG

9.INSPECT ECM TERMINAL OF MISFIRING CYLINDER (#10, #20, #30, #40, #50 AND/OR #60 VOLTAGE)

1. Turn the ignition switch ON.

1. Measure the voltage between the applicable terminals of the E15 and E17 ECM connectors.

   Standard voltage:

     Tester Connection | Specified Condition
     #10 (E17-2) - (E15-7) E01 | 9 to 14 V
     #20 (E17-3) - (E15-7) E01 | 9 to 14 V
     #30 (E17-4) - (E15-7) E01 | 9 to 14 V
     #40 (E17-5) - (E15-7) E01 | 9 to 14 V
     #50 (E17-6) - (E15-7) E01 | 9 to 14 V
     #60 (E17-7) - (E15-7) E01 | 9 to 14 V

| OK |

Go to step 11

NG |

10.CHECK WIRE HARNESS (INJECTOR - ECM)

1. Disconnect the injector connector (of the misfiring cylinder).

1. Disconnect the E17 ECM connector.

1. Turn the ignition switch ON.

1. Measure the resistance and voltage of the wire harness side connectors.

   Standard voltage:

     Cylinder | Tester Connection | Specified Condition
     No. 1 | F5-1 - Ground | 11 to 14 V
     No. 2 | F6-1 - Ground | 11 to 14 V
     No. 3 | F7-1 - Ground | 11 to 14 V
     No. 4 | F8-1 - Ground | 11 to 14 V
     No. 5 | F18-1 - Ground | 11 to 14 V
     No. 6 | F19-1 - Ground | 11 to 14 V

   Standard resistance:

     Cylinder | Tester Connection | Specified Condition
     No. 1 | F5-1 or E17-2 (#10) - Ground | 10 kΩ or higher
     No. 1 | F5-1 - E17-2 (#10) | Below 1 Ω
     No. 2 | F6-1 or E17-3 (#20) - Ground | 10 kΩ or higher
     No. 2 | F6-1 - E17-3 (#20) | Below 1 Ω
     No. 3 | F7-1 or E17-4 (#30) - Ground | 10 kΩ or higher
     No. 3 | F7-1 - E17-4 (#30) | Below 1 Ω
     No. 4 | F8-1 or E17-5 (#40) - Ground | 10 kΩ or higher
     No. 4 | F8-1 - E17-5 (#40) | Below 1 Ω
     No. 5 | F18-1 or E17-6 (#50) - Ground | 10 kΩ or higher
     No. 5 | F18-1 - E17-6 (#50) | Below 1 Ω
     No. 6 | F19-1 or E17-7 (#60) - Ground | 10 kΩ or higher
     No. 6 | F19-1 - E17-7 (#60) | Below 1 Ω

| NG |

REPAIR OR REPLACE HARNESS AND CONNECTOR

OK |

11.CHECK FUEL INJECTOR OF MISFIRING CYLINDER

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

| NG |

REPLACE FUEL INJECTOR ASSEMBLY

OK |

12.CHECK VALVE CLEARANCE OF MISFIRING CYLINDER

| NG |

ADJUST VALVE CLEARANCE

OK |

13.CHECK AIR INDUCTION SYSTEM

1. Check the air induction system for vacuum leakage.

   OK:
     No leakage from air induction system.

| NG |

REPAIR OR REPLACE AIR INDUCTION SYSTEM

OK |

14.CHECK VALVE TIMING (CHECK FOR LOOSE AND JUMPED TOOTH ON TIMING CHAIN)

1. Remove the cylinder head cover.

1. Turn the crankshaft pulley, and align its groove with the timing mark "0" of the timing chain cover.

1. Check that the timing marks of the camshaft timing gears are aligned with the timing marks of the bearing cap as shown in the illustration.
   If not, turn the crankshaft 1 revolution (360°) and align the marks as above.

   OK:
     Timing marks on camshaft timing gears are aligned as shown in illustration.

| NG |

ADJUST VALVE TIMING

OK |

15.CHECK FUEL PRESSURE

1. Check the fuel pressure.

| NG |

CHECK AND REPLACE FUEL PUMP, PRESSURE REGULATOR, FUEL PIPE LINE AND FILTER

OK |

16.READ DATA LIST (COOLANT TEMP)

1. Connect the intelligent tester to the DLC3.

1. Turn the ignition switch ON and turn the tester ON.

1. Enter the following menus items: Powertrain / Engine and ECT / Data List / Coolant Temp.

1. 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 95°C (167°F and 203°F)

| NG |

REPLACE ENGINE COOLANT TEMPERATURE SENSOR

OK |

17.READ DATA LIST (MAF)

1. Connect the intelligent tester to the DLC3.

1. Turn the ignition switch ON and turn the tester ON.

1. Enter the following menu items: Powertrain / Engine and ECT / Data List / Coolant Temp and MAF.

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

1. Read the MAF with the engine in an idling condition and at an engine speed of 2,500 rpm.

   Standard:
     MAF while engine idling: Between 3.2 g/s and 4.7 g/s (shift position: N, A/C: OFF).
     MAF at engine speed of 2,500 rpm: Between 13.1 g/s and 18.9 g/s (shift position: N, A/C: OFF).

| NG |

REPLACE MASS AIR FLOW METER

OK |

CHECK FOR INTERMITTENT PROBLEMS