2Az-Fe Engine Control System. Dtc P0300 Random / Multiple Cylinder Misfire Detected

When the engine misfires, high concentrations of hydrocarbons (HC) enter the exhaust gas. Extremely 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 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 count exceeds the threshold levels, and could cause emission control system performance deterioration, the ECM illuminates the MIL and sets a DTC.

DTC No.	DTC Detection Condition	Trouble Area
P0300	Simultaneous misfiring of several cylinders occurs and one of following conditions below is detected (2 trip detection logic): High temperature misfire occurs in three-way catalytic converter (MIL blinks) Emission deterioration misfire occurs (MIL illuminates)	Open or short in engine wire harness Connector connections Vacuum hose connections Ignition system Fuel injector assembly Fuel pressure Fuel line Fuel pump assembly Mass air flow meter Engine coolant temperature sensor Compression pressure Valve clearance Valve timing PCV valve and hose PCV hose connections Intake system ECM
P0301 P0302 P0303 P0304	Misfiring of a specific cylinder occurs and one of following conditions below is detected (2 trip detection logic): High temperature misfire occurs in three-way catalytic converter (MIL blinks) Emission deterioration misfire occurs (MIL illuminates)

When DTCs for misfiring cylinders are randomly 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.

CONFIRMATION DRIVING PATTERN

Connect the intelligent tester to the DLC3.
Turn the ignition switch to ON.
Turn the tester on.
Record the DTC(s) and freeze frame data.
Using the tester, switch the ECM from normal mode to check mode (CAMRY_ACV40 RM000000PDL01VX.html).
Read the misfire counts of each cylinder, Cylinder #1 Misfire Count to Cylinder #4 Misfire Count, with the engine idling. If any misfire count is displayed, skip the following confirmation driving pattern.
Drive the vehicle several times with the conditions, such as engine speed 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. Confirm the Misfire RPM and Misfire Load in the Data List.

Engine Speed
Duration
Idling
8 minutes or more
1000
4.5 minutes or more
2000
2.5 minutes or more
3000
1.5 minutes or more
Check whether misfires have occurred by checking DTCs and freeze frame data.
HINT:
Do not turn the ignition 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 are cleared.
Record the DTC(s), freeze frame data and misfire counts.
Turn the ignition switch off and wait for at least 5 seconds.

WIRING DIAGRAM

Refer to DTC P0100 (CAMRY_ACV40 RM000003SKB00XX_07.html).

INSPECTION PROCEDURE

HINT:

If any DTCs other than misfire DTCs are output, troubleshoot those DTCs first.
Read freeze frame data using the intelligent tester. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. 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 is considered to be a possible cause of the problem:

There was insufficient fuel in the tank.
Improper fuel is used.
The spark plugs have been contaminated.
The problem requires further diagnosis.

After finishing repairs, check the misfire counts of the cylinders (Cylinder #1 Misfire Count to Cylinder #4 Misfire Count).
Be sure to confirm that no misfiring cylinder DTCs are stored again by conducting the confirmation driving pattern after finishing repairs.
When one of Short FT #1 or Long FT #1 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 misfires have occurred only while warming up the engine.
An extremely imbalanced drive wheel which causes body vibration may cause misfire DTCs detection.

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

Connect the intelligent tester to the DLC3.

Turn the ignition switch to ON.

Turn the tester on.

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

Read the DTCs.

Result:

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

HINT:

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

GO TO DTC CHART (CAMRY_ACV40 RM000000PDF0C4X.html)

A

2.CHECK PCV HOSE CONNECTIONS

Check the PCV hose connections.
OK:
PCV hose is correctly connected and is not damaged.

REPAIR OR REPLACE PCV HOSE

OK

3.READ VALUE USING INTELLIGENT TESTER (MISFIRE RPM AND MISFIRE LOAD)

Connect the intelligent tester to the DLC3.

Turn the ignition switch to ON.

Turn the tester on.

Enter the following menus: Powertrain / Engine and ECT / Data List / All Data / Misfire RPM and Misfire Load.

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

4.READ VALUE USING INTELLIGENT TESTER (CYLINDER #1, #2, #3 AND #4 MISFIRE COUNT)

Connect the intelligent tester to the DLC3.

Turn the ignition switch to ON.

Turn the tester on.

Enter the following menus: Powertrain / Engine and ECT / Data List / All Data / Cylinder #1 (to #4) Misfire Count.

Read each value for Cylinder #1 (to #4) Misfire Count displayed on the tester. If no misfire counts occur in any cylinders, perform steps [A] and [B] and then check the misfire counts again.

Drive the vehicle with the Misfire RPM and Misfire Load noted in the "READ VALUE USING INTELLIGENT TESTER (MISFIRE RPM AND MISFIRE LOAD)" procedures above [A].

Read the Cylinder #1 (to #4) Misfire Count or DTCs displayed on the tester [B].

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.

Go to step 17

A

5.INSPECT SPARK PLUG

Inspect the spark plug of the misfiring cylinder (CAMRY_ACV40 RM000001QVP03SX_01_0002.html).

REPLACE SPARK PLUG (CAMRY_ACV40 RM000001QVN005X.html)

OK

6.CHECK FOR SPARK (SPARK TEST)

Perform a spark test (CAMRY_ACV40 RM000001QVP03SX_01_0001.html).
CAUTION:
Always disconnect all injector connectors.
NOTICE:
Do not crank the engine for more than 2 seconds.
OK:
Spark jumps across electrode gap.

Go to step 36

OK

7.CHECK CYLINDER COMPRESSION PRESSURE OF MISFIRING CYLINDER

Measure the cylinder compression pressure of the misfiring cylinder (CAMRY_ACV40 RM000000YHZ01GX_01_0008.html).

CHECK ENGINE TO DETERMINE CAUSE OF LOW COMPRESSION

OK

8.CHECK FUEL INJECTOR ASSEMBLY (POWER SOURCE)

Camry. Acv40 Gsv40.2Az-Fe Engine Control System.Sfi System.
Dtc
P0300 Random / Multiple Cylinder Misfire Detected

Disconnect the fuel injector assembly connectors.

Turn the ignition switch to ON.

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

Standard Voltage:

Tester Connection	Condition	Specified Condition
C7-1 - Body ground	Ignition switch ON	11 to 14 V
C8-1 - Body ground	Ignition switch ON	11 to 14 V
C9-1 - Body ground	Ignition switch ON	11 to 14 V
C10-1 - Body ground	Ignition switch ON	11 to 14 V

Text in Illustration
*1	Front view of wire harness connector (to Fuel Injector Assembly)

Turn the ignition switch off.

Reconnect the fuel injector assembly connectors.

CHECK FUEL INJECTOR CIRCUIT (CAMRY_ACV40 RM000000ZRM04OX.html)

OK

9.CHECK HARNESS AND CONNECTOR (FUEL INJECTOR ASSEMBLY - ECM)

Disconnect the fuel injector assembly connectors.

Disconnect the ECM connector.

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

Standard Resistance (Check for Open):

Tester Connection	Condition	Specified Condition
C7-2 - C24-108 (#10)	Always	Below 1 Ω
C9-2 - C24-107 (#20)	Always	Below 1 Ω
C8-2 - C24-106 (#30)	Always	Below 1 Ω
C10-2 - C24-105 (#40)	Always	Below 1 Ω

Standard Resistance (Check for Short):

Tester Connection	Condition	Specified Condition
C7-2 or C24-108 (#10) - Body ground	Always	10 kΩ or higher
C9-2 or C24-107 (#20) - Body ground	Always	10 kΩ or higher
C8-2 or C24-106 (#30) - Body ground	Always	10 kΩ or higher
C10-2 or C24-105 (#40) - Body ground	Always	10 kΩ or higher

Reconnect the fuel injector assembly connectors.

Reconnect the ECM connector.

REPAIR OR REPLACE HARNESS OR CONNECTOR (FUEL INJECTOR ASSEMBLY - ECM)

OK

10.INSPECT FUEL INJECTOR ASSEMBLY OF MISFIRING CYLINDER

Inspect the fuel injector assembly injection (whether fuel volume is high or low, and whether injection pattern is poor) (CAMRY_ACV40 RM000000YCT00PX.html).

REPLACE FUEL INJECTOR ASSEMBLY (CAMRY_ACV40 RM000000YCV01KX.html)

OK

11.CHECK INTAKE SYSTEM

Check the intake system for vacuum leaks.
OK:
No leaks in the intake system.

REPAIR OR REPLACE INTAKE SYSTEM

OK

12.CHECK FUEL PRESSURE

Check the fuel pressure (CAMRY_ACV40 RM000000YCR00RX_01_0002.html).

Go to step 38

OK

13.READ VALUE USING INTELLIGENT TESTER (COOLANT TEMP)

Connect the intelligent tester to the DLC3.

Turn the ignition switch to ON.

Turn the tester on.

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

Read the Coolant Temp twice, when the engine is both cold and warmed up.
Standard value:
With cold engine:
Same as ambient air temperature.
With warm engine:
Between 75°C and 100°C (176°F and 212°F).

REPLACE ENGINE COOLANT TEMPERATURE SENSOR (CAMRY_ACV40 RM000002A42028X.html)

OK

14.READ VALUE USING INTELLIGENT TESTER (MAF)

Connect the intelligent tester to the DLC3.

Turn the ignition switch to ON.

Turn the tester on.

Enter the following menus: Powertrain / Engine and ECT / Data List / All Data / MAF and Coolant Temp.

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

Read the MAF with the engine in an idling condition and at an engine speed of 2500 rpm.
Standard:
Between 6 g/sec. and 10 g/sec. (shift position: N, A/C: OFF).

Go to step 29

OK

15.CHECK VALVE TIMING

Remove the cylinder head cover.

Turn the crankshaft pulley, then align its groove with the timing mark "0" on the timing chain cover.

Check that the point marks on the camshaft timing gears are aligned with the timing chain cover surface as shown in the illustration.
If not, turn the crankshaft 1 revolution (360°), then align the marks as above.
OK:
Alignment marks on camshaft timing gears are aligned as shown in the illustration.
Text in Illustration
*1
Alignment Marks
*2
Groove

Reinstall the cylinder head cover.

ADJUST VALVE TIMING (CAMRY_ACV40 RM000000YI601HX.html)

OK

16.CHECK VALVE CLEARANCE OF MISFIRING CYLINDER

Check the valve clearance (CAMRY_ACV40 RM000001A8Z02JX.html).

Go to step 29

ADJUST VALVE CLEARANCE (CAMRY_ACV40 RM000001A8Z02JX.html)

17.CHECK INTAKE SYSTEM

Check the intake system for vacuum leaks.
OK:
No leaks in the intake system.

REPAIR OR REPLACE INTAKE SYSTEM

OK

18.CHECK FUEL PRESSURE

Check the fuel pressure (CAMRY_ACV40 RM000000YCR00RX_01_0002.html).

Go to step 38

OK

19.READ VALUE USING INTELLIGENT TESTER (COOLANT TEMP)

Check the fuel pressure (CAMRY_ACV40 RM000000YCR00RX_01_0002.html).
Standard pressure:
304 to 343 kPa (3.1 to 3.5 kgf/cm², 44.1 to 49.7 psi)

REPLACE ENGINE COOLANT TEMPERATURE SENSOR (CAMRY_ACV40 RM000002A42028X.html)

OK

20.READ VALUE USING INTELLIGENT TESTER (MAF)

Connect the intelligent tester to the DLC3.

Turn the ignition switch to ON.

Turn the tester on.

Enter the following menus: Powertrain / Engine and ECT / Data List / All Data / MAF and Coolant Temp.

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

Read the MAF with the engine in an idling condition and at an engine speed of 2500 rpm.
Standard:
Between 6 g/sec. and 10 g/sec. (shift position: N, A/C: OFF).

Go to step 29

OK

21.CHECK VALVE TIMING

Remove the cylinder head cover.

Turn the crankshaft pulley, then align its groove with the timing mark "0" on the timing chain cover.

Check that the point marks on the camshaft timing gears are aligned with the timing chain cover surface as shown in the illustration.
If not, turn the crankshaft 1 revolution (360°), then align the marks as above.
OK:
Alignment marks on camshaft timing gears are aligned as shown in the illustration.
Text in Illustration
*1
Alignment Marks
*2
Groove

Reinstall the cylinder head cover.

ADJUST VALVE TIMING (CAMRY_ACV40 RM000000YI601HX.html)

OK

22.INSPECT SPARK PLUG

Inspect the spark plug of the misfiring cylinder (CAMRY_ACV40 RM000001QVP03SX_01_0002.html).

REPLACE SPARK PLUG (CAMRY_ACV40 RM000001QVN005X.html)

OK

23.CHECK FOR SPARK (SPARK TEST)

Perform a spark test (CAMRY_ACV40 RM000001QVP03SX_01_0001.html).
CAUTION:
Always disconnect all injector connectors.
NOTICE:
Do not crank the engine for more than 2 seconds.
OK:
Spark jumps across electrode gap.

Go to step 36

OK

24.CHECK CYLINDER COMPRESSION PRESSURE

Measure the cylinder compression pressure of the misfiring cylinder (CAMRY_ACV40 RM000000YHZ01GX_01_0008.html).

CHECK ENGINE TO DETERMINE CAUSE OF LOW COMPRESSION

OK

25.CHECK FUEL INJECTOR ASSEMBLY (POWER SOURCE)

Disconnect the fuel injector assembly connectors.

Turn the ignition switch to ON.

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

Standard Voltage:

Tester Connection	Condition	Specified Condition
C7-1 - Body ground	Ignition switch ON	11 to 14 V
C8-1 - Body ground	Ignition switch ON	11 to 14 V
C9-1 - Body ground	Ignition switch ON	11 to 14 V
C10-1 - Body ground	Ignition switch ON	11 to 14 V

Text in Illustration
*1	Front view of wire harness connector (to Fuel Injector Assembly)

Turn the ignition switch off.

Reconnect the fuel injector assembly connectors.

CHECK FUEL INJECTOR CIRCUIT (CAMRY_ACV40 RM000000ZRM04OX.html)

OK

26.CHECK HARNESS AND CONNECTOR (FUEL INJECTOR ASSEMBLY - ECM)

Disconnect the fuel injector assembly connectors.

Disconnect the ECM connector.

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

Standard Resistance (Check for Open):

Tester Connection	Condition	Specified Condition
C7-2 - C24-108 (#10)	Always	Below 1 Ω
C9-2 - C24-107 (#20)	Always	Below 1 Ω
C8-2 - C24-106 (#30)	Always	Below 1 Ω
C10-2 - C24-105 (#40)	Always	Below 1 Ω

Standard Resistance (Check for Short):

Tester Connection	Condition	Specified Condition
C7-2 or C24-108 (#10) - Body ground	Always	10 kΩ or higher
C9-2 or C24-107 (#20) - Body ground	Always	10 kΩ or higher
C8-2 or C24-106 (#30) - Body ground	Always	10 kΩ or higher
C10-2 or C24-105 (#40) - Body ground	Always	10 kΩ or higher

Reconnect the fuel injector assembly connectors.

Reconnect the ECM connector.

REPAIR OR REPLACE HARNESS OR CONNECTOR (FUEL INJECTOR ASSEMBLY - ECM)

OK

27.INSPECT FUEL INJECTOR ASSEMBLY OF MISFIRING CYLINDER

Inspect the fuel injector assembly injection (whether fuel volume is high or low, and whether injection pattern is poor) (CAMRY_ACV40 RM000000YCT00PX.html).

REPLACE FUEL INJECTOR ASSEMBLY (CAMRY_ACV40 RM000000YCV01KX.html)

OK

28.CHECK VALVE CLEARANCE OF MISFIRING CYLINDER

Check the valve clearance (CAMRY_ACV40 RM000001A8Z02JX.html).

ADJUST VALVE CLEARANCE (CAMRY_ACV40 RM000001A8Z02JX.html)

OK

29.CHECK HARNESS AND CONNECTOR

Check the connection and terminal contact pressure of connectors and wire harness between the mass air flow meter and ECM (CAMRY_ACV40 RM000000UZ301ZX.html).
HINT:
Repair any problems.

NEXT

30.PERFORM CONFIRMATION DRIVING PATTERN

Connect the intelligent tester to the DLC3.

Turn the ignition switch to ON.

Turn the tester on.

Clear the DTCs (CAMRY_ACV40 RM000000PDK0LEX.html).

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

NEXT

31.CHECK WHETHER DTC OUTPUT RECURS (DTC P0300, P0301, P0302, P0303, P0304)

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

Input the DTC: P0300, P0301, P0302, P0303 or P0304.

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

END

A

32.CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER SUB-ASSEMBLY - ECM)

Disconnect the mass air flow meter sub-assembly connector.

Disconnect the ECM connector.

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

Standard Resistance (Check for Open):

Tester Connection
Condition
Specified Condition
C2-5 (VG) - C24-118 (VG)
Always
Below 1 Ω
C2-4 (E2G) - C24-116 (E2G)
Always
Below 1 Ω

Standard Resistance (Check for Short):

Tester Connection
Condition
Specified Condition
C2-5 (VG) or C24-118 (VG) - Body ground
Always
10 kΩ or higher

Reconnect the ECM connector.

Reconnect the mass air flow meter sub-assembly connector.

REPAIR OR REPLACE HARNESS OR CONNECTOR (MASS AIR FLOW METER SUB-ASSEMBLY - ECM)

OK

33.REPLACE MASS AIR FLOW METER

Replace the mass air flow meter (CAMRY_ACV40 RM000002A3Z001X.html).

HINT:

If the result of the inspection performed in steps 14 and 20 indicated no problem, proceed to the next step without replacing the mass air flow meter.

NEXT

34.PERFORM CONFIRMATION DRIVING PATTERN

Connect the intelligent tester to the DLC3.

Turn the ignition switch to ON.

Turn the tester on.

Clear the DTCs (CAMRY_ACV40 RM000000PDK0LEX.html).

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

NEXT

35.CONFIRM WHETHER MALFUNCTION HAS BEEN SUCCESSFULLY REPAIRED

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

Input the DTC: P0300, P0301, P0302, P0303 or P0304.

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

REPLACE ECM (CAMRY_ACV40 RM0000017UO02YX.html)

END

36.CHANGE TO NORMAL SPARK PLUG AND CHECK SPARK OF MISFIRING CYLINDER

Change the installed spark plug to a known good spark plug.

Perform a spark test (CAMRY_ACV40 RM000001QVP03SX_01_0001.html).
CAUTION:
Always disconnect all injector connectors.
NOTICE:
Do not crank the engine for more than 2 seconds.
OK:
Spark jumps across electrode gap.

Go to step 37

REPLACE SPARK PLUG (CAMRY_ACV40 RM000001QVN005X.html)

37.CHANGE TO NORMAL IGNITION COIL ASSEMBLY AND CHECK SPARK OF MISFIRING CYLINDER

Change the installed ignition coil assembly to a known good ignition coil assembly.

Perform a spark test (CAMRY_ACV40 RM000001QVP03SX_01_0001.html).
CAUTION:
Always disconnect all injector connectors.
NOTICE:
Do not crank the engine for more than 2 seconds.
OK:
Spark jumps across electrode gap.

REPLACE ECM (CAMRY_ACV40 RM0000017UO02YX.html)

REPLACE IGNITION COIL ASSEMBLY (CAMRY_ACV40 RM000001QVM02HX.html)

38.CHECK FUEL LINE

Check the fuel lines for leaks or blockage.

REPAIR OR REPLACE FUEL LINE

REPLACE FUEL PUMP (CAMRY_ACV40 RM000001IRA018X.html)

Engine Speed	Duration
Idling	8 minutes or more
1000	4.5 minutes or more
2000	2.5 minutes or more
3000	1.5 minutes or more

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

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

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