P0300

2AZ-FE ENGINE CONTROL SYSTEM: SFI SYSTEM: P0300-P0304: 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

DESCRIPTION

When the engine misfires, high concentrations of hydrocarbons (HC) enter the exhaust gas. High HC concentration levels can cause increase in exhaust emission levels. Extremely 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 (CMP) sensor and the Crankshaft Position (CKP) sensor. The CMP 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 count exceeds the threshold levels, and could cause emission deterioration, the ECM illuminates the MIL and sets a DTC.

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.

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 20 to 50 misfires per 1000 crankshaft revolutions) occurs once.
- An excessive misfiring rate (approximately 20 to 50 misfires per 1,000 crankshaft revolutions) occurs a total of 4 times.

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).
HINT: If a catalyst damage misfire occurs, the monitor informs the driver by blinking the MIL (1 trip).

- In every 200 crankshaft revolutions at a high engine rpm, the threshold misfiring percentage is recorded once.
- In every 200 crankshaft revolutions at a normal engine rpm, 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-damaged-misfire (MIL blinks):

MONITOR RESULT

Refer to CHECKING MONITOR STATUS Mode 6 Data.

WIRING DIAGRAM

Wiring diagram of the ignition system.

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 DTC(s) and freeze frame data.
5. Using the Techstream, switch the ECM from normal mode to check mode Check Mode Procedure.
6. Read the misfire counts of each cylinder, Cylinder #1 Misfire Rate to Cylinder #4 Misfire Rate, with the engine in an idling condition. If any misfire count is displayed, skip the following confirmation driving pattern.
7. Drive the vehicle several times with the 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 operate the vehicle for the period of time shown in the table below, using the Misfire RPM and Misfire Load in the Data List.

8. Check whether misfires have occurred by checking DTCs and freeze frame data.
HINT: Do not turn the ignition switch to 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.

9. Record the DTC(s), freeze frame data and misfire counts.
10. Turn the ignition switch to OFF and wait for at least 5 seconds.

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 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 Misfire Rate to Cylinder #4 Misfire Rate]).
- Be sure to confirm that no misfiring cylinder DTCs are set again by conducting the confirmation driving pattern after finishing repairs.
- 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 the Coolant Temp in the freeze frame data is less than 75°C (167°F), the misfire have occurred only while warming up the engine.
- An extremely imbalanced drive wheel which causes body vibration may cause misfire DTCs detection.

PROCEDURE

1. CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO MISFIRE DTCS)
(a) Connect the Techstream to the DLC3.
(b) Turn the ignition switch to ON.
(c) Turn the Techstream ON.
(d) Select the following menu items: Powertrain / Engine and ECT / Trouble Codes.
(e) Read DTCs.
HINT: Write down indicated DTCs.

Result

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

B -- GO TO DTC CHART
A -- Continue to next step.
2. READ VALUE USING TECHSTREAM (MISFIRE RPM AND MISFIRE LOAD)
(a) Connect the Techstream to the DLC3.
(b) Turn the ignition switch to ON.
(c) Turn the Techstream ON.
(d) Select the following menu items: Powertrain / Engine and ECT / Data List / Misfire / Misfire RPM and Misfire Load.
(e) 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.
3. CHECK PCV HOSE CONNECTIONS
OK:
PCV hose is correctly connected and is not damaged.
NG -- REPAIR OR REPLACE PCV HOSE
OK -- Continue to next step.
4. READ VALUE USING TECHSTREAM (CATALYST OT MF F/C)
(a) Connect the Techstream to the DLC3.
(b) Turn the ignition switch to ON.
(c) Turn the Techstream ON.
(d) Select the following menu items: Powertrain / Engine and ECT / Data List / Catalyst OT MF F/C.
(e) Read the value displayed on the Techstream.

Result

B -- READ VALUE USING TECHSTREAM (CYLINDER MISFIRE RATE)
A -- Continue to next step.
5. PERFORM ACTIVE TEST USING TECHSTREAM (PROHIBIT CAT OT F/C)
(a) Connect the Techstream to the DLC3.
(b) Turn the ignition switch to ON.
(c) Turn the Techstream ON.
(d) Select the following menu items: Powertrain / Engine and ECT / Active Test / Prohibit the Catalyst OT Misfire prevent F/C.
(e) 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. READ VALUE USING TECHSTREAM (CYLINDER MISFIRE RATE)
- (a) Select the following menu items: Powertrain / Engine and ECT / Data List / Misfire / Cylinder #1 Misfire Rate, #2, #3 and #4.
- (b) Start the engine and allow the engine to idle.
- (c) Read each value for Cylinder #1 Misfire Rate to #4 displayed on the Techstream. If no misfire counts occur in any cylinders, perform steps (d) and (e) and then check the misfire counts again.
- (d) Drive the vehicle with the Misfire RPM and Misfire Load noted in the "READ VALUE USING TECHSTREAM (MISFIRE RPM AND MISFIRE LOAD)" procedures above.
- (e) Read the Cylinder #1 Misfire Rate to #4 or DTCs displayed 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 ECT 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 the 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) Remove the ignition coil and the spark plug from the misfiring cylinder.
(b) Measure the spark plug electrode gap.
Standard gap:
1.0 to 1.1 mm (0.039 to 0.043 in.)
(c) Check the electrode for carbon deposits.

Recommended spark plug:

NOTICE: If the electrode gap is out of standard, replace the spark plug. Do not adjust the electrode gap.
(d) Reinstall the ignition coil.
NG -- REPLACE SPARK PLUG
OK -- Continue to next step.
8. CHECK FOR SPARKS AND IGNITION

(a) Disconnect the injector connectors to prevent the engine from starting.
CAUTION: Always disconnect all injector connectors.
(b) Remove the ignition coil from the cylinder head.
(c) Install the spark plug onto the ignition coil.
(d) Attach the spark plug assembly to the cylinder head.
(e) Crank the engine for less than 2 seconds and check the spark.
NOTICE: Do not crank the engine for more than 2 seconds.

OK:
Sparks jump across electrode gap.
(f) Install the ignition coil.
(g) Reconnect the injector connectors.
NG -- CHANGE TO NORMAL SPARK PLUG 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. INSPECT ECM TERMINAL OF MISFIRING CYLINDER (#10, #20, #30 AND /OR #40 VOLTAGE)

(a) Disconnect the ECM connector.
(b) Turn the ignition switch to ON.
(c) Measure the voltage according to the value(s) in the table below.
Standard voltage:

(d) Reconnect the ECM connector.
NG -- GO TO FUEL INJECTOR CIRCUIT
OK -- Continue to next step.
11. CHECK FUEL INJECTOR OF MISFIRING CYLINDER
(a) Check the injector injection (whether fuel volume is high or low, and whether injection pattern is poor) Testing and Inspection.
NG -- REPLACE FUEL INJECTOR
OK -- Continue to next step.
12. CHECK VALVE CLEARANCE OF MISFIRING CYLINDER
(a) Check the valve clearance Adjustments.
NG -- ADJUST VALVE CLEARANCE
OK -- Continue to next step.
13. CHECK AIR INDUCTION SYSTEM
(a) Check the air induction system for vacuum leak Testing and Inspection.
OK:
No leak from air induction system.
NG -- REPAIR OR REPLACE AIR INDUCTION SYSTEM
OK -- Continue to next step.
14. CHECK VALVE TIMING P0011
NG -- ADJUST VALVE TIMING
OK -- Continue to next step.
15. CHECK FUEL PRESSURE
(a) Check the fuel pressure Testing and Inspection.
NG -- REPAIR OR REPLACE FUEL PUMP, PRESSURE REGULATOR, FUEL PIPE LINE OR FILTER
OK -- Continue to next step.
16. READ VALUE USING TECHSTREAM (COOLANT TEMP) P0171
NG -- REPLACE ENGINE COOLANT TEMPERATURE SENSOR
OK -- Continue to next step.
17. INSPECT MASS AIR FLOW METER P0171
NG -- REPLACE MASS AIR FLOW METER
OK -- REPLACE ECM
18. CHECK AIR INDUCTION SYSTEM
(a) Check the air induction system for vacuum leak Testing and Inspection.
OK:
No leak from air induction system.
NG -- REPAIR OR REPLACE AIR INDUCTION SYSTEM
OK -- Continue to next step.
19. CHECK VALVE TIMING P0011
NG -- ADJUST VALVE TIMING
OK -- Continue to next step.
20. CHECK FUEL PRESSURE
(a) Check the fuel pressure Testing and Inspection.
NG -- REPAIR OR REPLACE FUEL PUMP, PRESSURE REGULATOR, FUEL PIPE LINE OR FILTER
OK -- Continue to next step.
21. READ VALUE USING TECHSTREAM (COOLANT TEMP) P0171
NG -- REPLACE ENGINE COOLANT TEMPERATURE SENSOR
OK -- Continue to next step.
22. INSPECT MASS AIR FLOW METER P0171
NG -- REPLACE MASS AIR FLOW METER
OK -- Continue to next step.
23. INSPECT SPARK PLUG

(a) Remove the ignition coil and the spark plug of the misfiring cylinder.
(b) Measure the spark plug electrode gap.
Standard gap:
1.0 to 1.1 mm (0.039 to 0.043 in.)
(c) Check the electrode for carbon deposits.

Recommended spark plug:

(a) Disconnect the injector connectors to prevent the engine from starting.
CAUTION: Always disconnect all injector connectors.
(b) Remove the ignition coil from the cylinder head.
(c) Install the spark plug onto the ignition coil.
(d) Attach the spark plug assembly to the cylinder head.
(e) Crank the engine for less than 2 seconds and check the spark.
NOTICE: Do not crank the engine for more than 2 seconds.

OK:
Sparks jump across electrode gap.
(f) Install the ignition coil.
(g) Reconnect the injector connectors.
NG -- CHANGE TO NORMAL SPARK PLUG 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. INSPECT ECM TERMINAL OF MISFIRING CYLINDER (#10, #20, #30 AND/OR #40 VOLTAGE)

(a) Disconnect the ECM connector.
(b) Turn the ignition switch to ON.
(c) Measure the voltage according to the value(s) in the table below.
Standard voltage:

(d) Reconnect the ECM connector.
NG -- GO TO FUEL INJECTOR CIRCUIT
OK -- Continue to next step.
27. CHECK FUEL INJECTOR OF MISFIRING CYLINDER
(a) Check the injector injection (whether fuel volume is high or low, and whether injection pattern is poor) Testing and Inspection.
NG -- REPLACE FUEL INJECTOR
OK -- Continue to next step.
28. CHECK VALVE CLEARANCE OF MISFIRING CYLINDER
(a) Check the valve clearance Adjustments.
NG -- ADJUST VALVE CLEARANCE
OK -- REPLACE ECM
29. CHANGE TO NORMAL SPARK PLUG AND CHECK SPARK OF MISFIRING CYLINDER
(a) Change the installed spark plug to a spark plug that functions normally.
(b) Perform a spark test.
CAUTION: Always disconnect all injector connectors.
NOTICE: 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 -- CHANGE TO NORMAL IGNITION COIL AND CHECK SPARK OF MISFIRING CYLINDER
OK -- REPLACE SPARK PLUG
30. CHANGE TO NORMAL IGNITION COIL AND CHECK SPARK OF MISFIRING CYLINDER
(a) Change the ignition coil to a ignition coil that functions normally.
(b) Perform a spark test.
CAUTION: Always disconnect all injector connectors.
NOTICE: 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 -- REPLACE ECM
OK -- REPLACE IGNITION COIL