P0303

1NZ-FXE ENGINE CONTROL SYSTEM: SFI SYSTEM: P0300: 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 a misfire occurs in the engine, hydrocarbons (HC) enter the exhaust gas in high concentrations. If this HC concentration is high enough, there could be an increase in exhaust emissions levels. High concentrations of HC can also increase the temperature of the catalyst, possibly damaging the catalyst. To prevent this increase in emissions and limit the possibility of thermal damage, the ECM monitors the misfire rate. When the temperature of the catalyst reaches a point of thermal degradation, the ECM will blink the MIL. For monitoring misfire, the ECM uses both the camshaft position sensor and the crankshaft position sensor. The camshaft position sensor is used to identify misfiring cylinders and the crankshaft position sensor is used to measure variations in the crankshaft rotation speed. The misfire counter increments when crankshaft rotation speed variations exceed threshold values.
If the misfiring rate exceeds the threshold value and could cause emissions deterioration, the ECM illuminates the MIL.

NOTE: When several codes for a misfiring cylinder are recorded repeatedly but no random misfire code is recorded, it indicates that the misfires have been detected and recorded at different times.

Reference: Inspection using oscilloscope
With the engine idling, check the waveform between terminals #10 to #40 and E01 of the ECM connectors.
HINT: The correct waveform is as shown.

MONITOR DESCRIPTION

The ECM illuminates the MIL (2 trip detection logic) if:

- The percent misfire exceeds the specified limit per 1,000 engine revolutions. One occurrence of excessive misfire during engine start will illuminate the MIL. After engine start, four occurrences of excessive misfire will illuminate the MIL.

The ECM blinks the MIL (immediately) if:

- The threshold for percent of misfire causing catalyst damage is reached 1 time per 200 engine revolutions at a high rpm, and 3 times in 200 engine revolutions at a normal rpm.
- The threshold for percent of misfire causing catalyst damage is reached.

MONITOR STRATEGY

TYPICAL ENABLING CONDITIONS

Misfire:

Monitor period of emission-related misfire:

Monitor period of catalyst-damaging misfire (MIL blinks):

TYPICAL MALFUNCTION THRESHOLDS

Monitor period of emission-related misfire:

Monitor period of catalyst-damaging misfire (MIL blinks):

MONITOR RESULT

Refer to CHECKING MONITOR STATUS Mode 6 Data.

WIRING DIAGRAM

CONFIRMATION DRIVING PATTERN

1. Connect Techstream to the DLC3.
2. Turn the power switch ON (IG).
3. Turn the tester on.
4. Record the DTC(s) and freeze frame data.
5. Using the tester, switch the ECM (included in the hybrid vehicle control ECU) from normal mode to check mode Check Mode Procedure.
6. Read the misfire counts of each cylinder (CYL #1 to #4) with the engine idling. If any misfire count is displayed, skip the following confirmation driving pattern.
7. Drive the vehicle several times with the conditions, such as an 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 drive the vehicle for the period of time shown in the table below, with 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 power 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.

9. Record the DTC(s), freeze frame data and misfire counts.
10. Turn the power switch 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 Techstream. The ECM (included in the hybrid vehicle control ECU) 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 freeze frame data.
- If the misfire still cannot be reproduced even though the conditions stored in the freeze frame data have been duplicated, one of the following factors is considered to be a possible cause of the problem:
1 The fuel level is low.
2 Improper fuel is used.
3 The spark plugs are dirty.
4 The problem is complex due to multiple factors.
- After finishing repairs, check that no misfires occur in each cylinder (CYL #1, #2, #3 and #4).
- Be sure to confirm that no misfiring cylinder DTCs are set again by conducting the confirmation driving pattern after the repairs.
- For 6 and 8 cylinder engines, the ECM intentionally does not set specific misfiring cylinder DTCs at a high engine RPM. If misfires only occur during high engine RPM driving, only DTC P0300 is set.
In the event of DTC P0300 being present, perform the following operations:
1 Clear the DTC DTC Check / Clear.
2 Start the engine and conduct the confirmation driving pattern.
3 Read the misfiring rates of each cylinder or DTC(s) using the tester.
4 Repair the cylinder(s) 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.
- When either 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 the COOLANT TEMP in the freeze frame data is less than 75°C (167°F), misfires occurred only while warming up the engine.
- An extremely imbalanced drive wheel which causes vibration may cause misfire DTCs to be detected.

PROCEDURE

1. CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO MISFIRE DTCS)
(a) Connect Techstream to the DLC3.
(b) Turn the power switch ON (IG).
(c) Turn the tester on.
(d) Select the following menu items: Powertrain / Engine and ECT / Trouble Code.
(e) Read the 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 Techstream to the DLC3.
(b) Turn the power switch ON (IG) and turn the tester on.
(c) Select the following menu items: Powertrain / Engine and ECT / Data List / Misfire / Misfire RPM and Misfire Load.
(d) Read and note the MISFIRE RPM and MISFIRE LOAD (engine 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 (HOSE CONNECTIONS)
OK:
PCV hose is connected correctly and is not damaged.
NG -- REPAIR OR REPLACE PCV HOSE
OK -- Continue to next step.

4. CHECK MISFIRE COUNT (CYL #1, #2, #3 AND #4)
(a) Connect Techstream to the DLC3.
(b) Turn the power switch ON (IG).
(c) Turn the tester on.
(d) Clear the DTCs DTC Check / Clear.
(e) Select the following menu items: Powertrain / Engine and ECT / Data List / Misfire / Cylinder #1 Misfire Rate, #2, #3 and #4.
(f) Put the engine in inspection mode Service Precautions.
(g) Read each value for CYL #1 to #4 displayed on the tester. If no misfire counts occur in any cylinders, perform the following procedures:
(1) Shift the shift selector lever to the D position.
(2) Check CYL #1 to #4.
(3) If misfire counts are still not displayed, perform the following two steps and then check the misfire counts again.
(h) Drive the vehicle with the MISFIRE RPM and MISFIRE LOAD noted in the "READ VALUE USING TECHSTREAM (MISFIRE RPM AND MISFIRE LOAD)" procedures above.
(i) Read the CYL #1 to #4 or DTCs displayed on the tester.
Result:

HINT:
- If it is difficult to reproduce misfires for each cylinder, check the Data List item, 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), it may only be possible to detect the misfire when the engine is cold.
- If the freeze frame data's record of the ENGINE RUN TIME is below 120 seconds, misfire may be detected immediately after the engine is started.

B -- CHECK AIR INDUCTION SYSTEM
A -- Continue to next step.

5. CHECK SPARK PLUG

(a) Remove the ignition coil and the spark plug of the misfiring cylinder.
(b) Measure the spark plug electrode gap.
Standard gap:
0.7 to 0.8 mm (0.028 to 0.032 in.)
Maximum electrode gap:
1.16 mm (0.046 in.)
(c) Check the electrode for carbon deposits.

Recommended spark plug:

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

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

6. CHECK FOR SPARK AND IGNITION
(a) Remove the ignition coil from the cylinder head.
(b) Install the spark plug onto the ignition coil.
(c) Connect Techstream to the DLC3.
(d) Turn the power switch ON (IG) and turn the tester on.
(e) Select the following menu items: Powertrain / Engine and ECT / Active Test / Fuel Cut All.
(f) Touch the spark plug tip to the cylinder head.
(g) Perform the Fuel Cut All operation (press the RIGHT or LEFT button to change to ON).
NOTE: When Fuel Cut All is OFF and the engine is cranked, fuel injection will occur.
(h) Crank the engine for less than 2 seconds and check for spark.
OK:
Sparks jump across electrode gap.
(i) Install the ignition coil.
NG -- CHANGE TO NORMAL SPARK PLUG AND CHECK SPARK OF MISFIRING CYLINDER (MISFIRING CYLINDER)
OK -- Continue to next step.

7. CHECK CYLINDER COMPRESSION PRESSURE (MISFIRING CYLINDER)
(a) Measure the cylinder compression pressure of the misfiring cylinder.
NG -- CHECK ENGINE TO DETERMINE CAUSE OF LOW COMPRESSION
OK -- Continue to next step.

8. INSPECT ECM TERMINAL VOLTAGE (MISFIRING CYLINDER)

(a) Turn the power switch ON (IG).
(b) Measure the voltage between the terminals of the ECM connector.
Standard voltage:

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.

9. CHECK HARNESS AND CONNECTOR (INJECTOR - ECM)

(a) Disconnect the injector connector (of the misfiring cylinder).
(b) Disconnect the E4 ECM connector.
(c) Turn the power switch ON (IG).
(d) Measure the resistance and voltage according to the value(s) in the table below.
Standard voltage:

Standard resistance:

(e) Reconnect the injector connector.
(f) Reconnect the ECM connector.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.

10. CHECK FUEL INJECTOR ASSEMBLY (MISFIRING CYLINDER)
(a) Check the injector injection (whether fuel volume is high or low, and whether injection pattern is poor).
NG -- REPLACE FUEL INJECTOR ASSEMBLY
OK -- Continue to next step.

11. CHECK VALVE CLEARANCE (MISFIRING CYLINDER)
NG -- ADJUST VALVE CLEARANCE
OK -- Continue to next step.

12. CHECK AIR INDUCTION SYSTEM
(a) Check the air induction system for vacuum leaks.
OK:
No leaks in air induction system.
NG -- REPAIR OR REPLACE AIR INDUCTION SYSTEM
OK -- Continue to next step.

13. CHECK FUEL PRESSURE
(a) Check the fuel pressure Testing and Inspection.
NG -- CHECK AND REPLACE FUEL PUMP, PRESSURE REGULATOR, FUEL PIPE LINE OR FILTER
OK -- Continue to next step.

14. READ VALUE USING TECHSTREAM (COOLANT TEMP) P0115
NG -- REPLACE ENGINE COOLANT TEMPERATURE SENSOR
OK -- Continue to next step.

15. READ VALUE USING TECHSTREAM (MAF) P0102
NG -- REPLACE MASS AIR FLOW METER
OK -- Continue to next step.

16. CHECK VALVE TIMING
NG -- ADJUST VALVE TIMING
OK -- REPLACE ECM
17. CHECK AIR INDUCTION SYSTEM
(a) Check the air induction system for vacuum leaks.
OK:
No leaks in air induction system.
NG -- REPAIR OR REPLACE AIR INDUCTION SYSTEM
OK -- Continue to next step.

18. CHECK FUEL PRESSURE
(a) Check the fuel pressure Testing and Inspection.
NG -- CHECK AND REPLACE FUEL PUMP, PRESSURE REGULATOR, FUEL PIPE LINE OR FILTER
OK -- Continue to next step.

19. READ VALUE USING TECHSTREAM (COOLANT TEMP) P0115
NG -- REPLACE ENGINE COOLANT TEMPERATURE SENSOR
OK -- Continue to next step.

20. READ VALUE USING TECHSTREAM (MAF) P0102
NG -- REPLACE MASS AIR FLOW METER
OK -- Continue to next step.

21. CHECK SPARK PLUG

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

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

22. CHECK SPARKS AND IGNITION
(a) Remove the ignition coil from the cylinder head.
(b) Install the spark plug onto the ignition coil.
(c) Connect Techstream to the DLC3.
(d) Turn the power switch ON (IG) and turn the tester on.
(e) Select the following menu items: Powertrain / Engine and ECT / Active Test / Fuel Cut All.
(f) Touch the spark plug tip to the cylinder head.
(g) Perform the Fuel Cut All operation (press the RIGHT or LEFT button to change to ON).
NOTE: When Fuel Cut All is OFF and the engine is cranked, fuel injection will occur.
(h) Crank the engine for less than 2 seconds and check for spark.
OK:
Sparks jump across electrode gap.
(i) Install the ignition coil.
NG -- CHANGE TO NORMAL SPARK PLUG AND CHECK SPARK OF MISFIRING CYLINDER (MISFIRING CYLINDER)
OK -- Continue to next step.

23. CHECK CYLINDER COMPRESSION PRESSURE
(a) Measure the cylinder compression pressure of the misfiring cylinder.
NG -- CHECK ENGINE TO DETERMINE CAUSE OF LOW COMPRESSION
OK -- Continue to next step.

24. CHECK HARNESS AND CONNECTOR (INJECTOR - ECM)

Standard resistance:

(e) Reconnect the injector connector.
(f) Reconnect the ECM connector.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.

25. INSPECT ECM TERMINAL VOLTAGE (MISFIRING CYLINDER)

(a) Turn the power switch ON (IG).
(b) Measure the voltage between the terminals of the ECM connector.
Standard voltage:

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.

26. CHECK FUEL INJECTOR ASSEMBLY (MISFIRING CYLINDER)
(a) Check the injector injection (whether fuel volume is high or low, and whether injection pattern is poor).
NG -- REPLACE FUEL INJECTOR ASSEMBLY
OK -- Continue to next step.

27. CHECK VALVE CLEARANCE (MISFIRING CYLINDER)
NG -- ADJUST VALVE CLEARANCE
OK -- Continue to next step.

28. CHECK VALVE TIMING
NG -- ADJUST VALVE TIMING
OK -- REPLACE ECM
29. CHANGE TO NORMAL SPARK PLUG AND CHECK SPARK OF MISFIRING CYLINDER (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.
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 -- 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
NG -- REPLACE ECM
OK -- REPLACE IGNITION COIL