P0304

2GR-FE 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

DTC P0305 - Cylinder 5 Misfire Detected

DTC P0306 - Cylinder 6 Misfire Detected

DESCRIPTION

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

HINT: 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: Inspection using an oscilloscope
With the engine idling, check the waveform between terminals #10 to #60 and E01 of the ECM connectors.

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).

- 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 once.
- 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 Three-Way Catalytic Converter (TWC) damage, is detected (2 trip detection logic).

- 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-damage-misfire (MIL blinks):

TYPICAL MALFUNCTION THRESHOLDS

Monitor period of emission-related-misfire:

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

MONITOR RESULT

Refer to CHECKING MONITOR STATUS Mode 6 Data.

WIRING DIAGRAM

CONFIRMATION DRIVING PATTERN

1. Connect the intelligent tester to the DLC3.
2. Turn the ignition switch to the ON position.
3. Turn the tester on.
4. Record the DTC(s) and freeze frame data.
5. Using the tester, select the check mode Check Mode Procedure.
6. Read the misfire counts of each cylinder (CYL #1 to #6) 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 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 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.

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

INSPECTION PROCEDURE
HINT:
- If any DTCs other than the 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 be helpful in determining whether the vehicle was running or stopped, whether the engine was warmed up or not, whether the air-fuel ratio was lean or rich, as well as other data recorded at the time of a malfunction.

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

- After finishing repairs, check the misfire counts of the cylinders (CYL #1, #2, #3, #4, #5 and #6).
- Be sure to confirm that no misfiring cylinder DTCs are set again by conducting the confirmation driving pattern after repairs.
- For 6 and 8 cylinder engines, the ECM intentionally does not set the specific misfiring cylinder DTCs at high engine RPM. If misfires occur only in high engine RPM areas, only DTC P0300 is set.
If DTC P0300 is 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 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 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 misfires have occurred only while warming up the engine.

PROCEDURE

1. CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO MISFIRE TO DTCS)
(a) Connect the intelligent tester to the DLC3.
(b) Turn the ignition switch to the ON position.
(c) Turn the tester on.
(d) Select the following menu items: DIAGNOSIS / ENHANCED OBD II / DTC INFO / CURRENT CODES.
(e) Read the DTCs.
Result:

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

B -- GO TO DTC CHART
A -- Continue to next step.
2. READ VALUE USING INTELLIGENT TESTER (MISFIRE RPM AND MISFIRE LOAD)
(a) Connect the intelligent tester to the DLC3.
(b) Turn the ignition switch to the ON position and turn the tester on.
(c) Select the following menu items: DIAGNOSIS / ENHANCED OBD II / 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 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, #4, #5 AND #6)
(a) Connect the intelligent tester to the DLC3 (Procedure "A").
(b) Turn the ignition switch to the ON position (Procedure "B").
(c) Turn the tester on (Procedure "C").
(d) Clear the DTCs DTC Check / Clear (Procedure "D").
(e) Select the following menu items: DIAGNOSIS / ENHANCED OBD II / DATA LIST / MISFIRE / CYL #1, #2, #3, #4, #5 and #6 (Procedure "E").
(f) Allow the engine to idle (Procedure "F").
(g) Read each value of CYL #1 to #6 displayed on the tester (Procedure "G").
(1) Shift the gear selector lever to the D position.
(2) Repeat procedures "E" to "G" above.
(3) Check the CYL #1 to #6.
(4) If misfire counts are still not displayed, perform procedures "I" and "J" and then check the misfire counts again.
(h) If no misfire counts occur in any cylinders, perform the following operations (Procedure "H").
(i) Drive the vehicle with the MISFIRE RPM and MISFIRE LOAD noted in step 2 (Procedure "I").
(j) Read the CYL #1 to #6 or DTCs displayed on the tester (Procedure "J").
Result:

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:
Between 1.0 mm and 1.1 mm (0.039 in. and 0.043 in.)
(c) Check the electrode for carbon deposits.

Require 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 SPARKS AND IGNITION (SPARK TEST)
(a) Disconnect the injector connectors to prevent the engine from starting.
(b) Install the spark plug to the ignition coil.
(c) Attach the spark plug assembly to the cylinder head cover (ground the spark plug).
(d) Crank the engine for less than 2 seconds and check the sparks.
NOTE: Do not crank the engine for more than 2 seconds.

OK:
Sparks jump across electrode gap.
(e) Reconnect the injector connectors.
NG -- CHANGE SPARK PLUG WITH NORMAL ONE AND CHECK FOR SPARKS OF MISFIRING CYLINDER
OK -- Continue to next step.
7. CHECK CYLINDER COMPRESSION PRESSURE OF MISFIRING CYLINDER
(a) Measure the cylinder compression pressure of the misfiring cylinder Engine.
OK -- INSPECT ECM TERMINAL OF MISFIRING CYLINDER (#10, #20, #30, #40, #50 AND/OR #60 VOLTAGE)
NG -- CHECK ENGINE TO DETERMINE CAUSE OF LOW COMPRESSION
8. CHANGE SPARK PLUG WITH NORMAL ONE AND CHECK FOR SPARKS OF MISFIRING CYLINDER
(a) Switch the spark plug with a spark plug that functions normally.
(b) Perform the spark test again (refer to step 6).
OK:
Sparks jump across electrode gap.
NG -- CHANGE TO NORMAL IGNITION COIL AND CHECK SPARK OF MISFIRING CYLINDER
OK -- REPLACE SPARK PLUG
9. INSPECT ECM TERMINAL OF MISFIRING CYLINDER (#10, #20, #30, #40, #50 AND/OR #60 VOLTAGE)

(a) Turn the ignition switch to the ON position.
(b) Measure the voltage between the terminals of the E8 and E7 ECM connectors.
Standard voltage:

OK -- CHECK FUEL INJECTOR OF MISFIRING CYLINDER
NG -- Continue to next step.
10. CHECK HARNESS AND CONNECTOR (INJECTOR - ECM)

(a) Disconnect the injector connector (of the misfiring cylinder).
(b) Disconnect the E7 ECM connector.
(c) Turn the ignition switch to the ON position.
(d) Measure the resistance and voltage between the injector and the ECM connector terminals.
Standard:
Cylinder No. 1

Cylinder No. 2

Cylinder No. 3

Cylinder No. 4

Cylinder No. 5

Cylinder No. 6

(e) Reconnect the injector connector.
(f) Reconnect the ECM connector.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
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 ASSEMBLY
OK -- Continue to next step.
12. CHECK AIR INDUCTION SYSTEM
(a) Check the air induction system for vacuum leakage.
OK:
No leakage from air induction system.
NG -- REPAIR OR REPLACE AIR INDUCTION SYSTEM
OK -- Continue to next step.
13. CHECK VALVE TIMING (CHECK FOR LOOSE AND JUMPED TEETH ON TIMING CHAIN)

(a) Remove the cylinder head covers RH and LH.
(b) Turn the crankshaft to align the matchmarks of the crankshaft.
(c) Align the notch of the crankshaft pulley to the "0" position.
(d) Check if the matchmarks of the camshaft pulley and camshaft bearing cap align.
(e) Turn the crankshaft clockwise by 360° if the matchmarks do not align. Check if they align once again.
OK:
The matchmarks of the camshaft pulley and the camshaft bearing cap align when the notch of the crankshaft pulley is in the "0" position.
NG -- ADJUST VALVE TIMING
OK -- Continue to next step.
14. CHECK FUEL PRESSURE
(a) Check the fuel pressure Testing and Inspection.
NG -- CHECK AND REPLACE FUEL PUMP, PRESSURE REGULATOR, FUEL PIPE LINE AND FILTER
OK -- Continue to next step.
15. READ VALUE USING INTELLIGENT TESTER (COOLANT TEMP)
(a) Connect the intelligent tester to the DLC3.
(b) Turn the ignition switch to the ON position.
(c) Turn the tester on.
(d) Select the following menu items: DIAGNOSIS / ENHANCED OBD II / DATA LIST / PRIMARY / COOLANT TEMP.
(e) 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 -- Continue to next step.
16. READ VALUE USING INTELLIGENT TESTER (MAF)
(a) Connect the intelligent tester to the DLC3.
(b) Turn the ignition switch to the ON position.
(c) Turn the tester on.
(d) Select the following menu items: DIAGNOSIS / ENHANCED OBD II / DATA LIST / PRIMARY / MAF and COOLANT TEMP.
(e) Allow the engine to idle until the COOLANT TEMP reaches 75°C (167°F) or more.
(f) Read the MAF with the engine in an idling condition and at an engine speed of 2,500 rpm.
Standard:
MAF while engine is 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 -- REPLACE ECM
17. CHECK AIR INDUCTION SYSTEM
(a) Check the air induction system for vacuum leakage.
OK:
No leakage from 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 AND FILTER
OK -- Continue to next step.
19. READ VALUE USING INTELLIGENT TESTER (COOLANT TEMP)
(a) Connect the intelligent tester to the DLC3.
(b) Turn the ignition switch to the ON position.
(c) Turn the tester on.
(d) Select the following menu items: DIAGNOSIS / ENHANCED OBD II / DATA LIST / PRIMARY / COOLANT TEMP.
(e) 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 -- Continue to next step.
20. INSPECT MASS AIR FLOW METER
(a) Connect the intelligent tester to the DLC3.
(b) Turn the ignition switch to the ON position.
(c) Turn the tester on.
(d) Select the following menu items: DIAGNOSIS / ENHANCED OBD II / DATA LIST / PRIMARY / MAF and COOLANT TEMP.
(e) Allow the engine to idle until the COOLANT TEMP reaches 75°C (167°F) or more.
(f) Read the MAF with the engine in an idling condition and at an engine speed of 2,500 rpm.
Standard:
MAF while engine is 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 -- 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) Disconnect the injector connectors to prevent the engine from starting.
(b) Install the spark plug to the ignition coil.
(c) Attach the spark plug assembly to the cylinder head cover (ground the spark plug).
(d) Crank the engine for less than 2 seconds and check the sparks.
NOTE: Do not crank the engine for more than 2 seconds.

OK:
Sparks jump across electrode gap.
(e) Reconnect the injector connectors.
NG -- CHANGE TO NORMAL SPARK PLUG AND CHECK SPARK OF MISFIRING CYLINDER
OK -- Continue to next step.
23. 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.
24. CHECK HARNESS AND CONNECTOR (INJECTOR - ECM)

Cylinder No. 2

Cylinder No. 3

Cylinder No. 4

Cylinder No. 5

Cylinder No. 6

(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 OF MISFIRING CYLINDER (#10, #20, #30, #40, #50 AND/OR #60 VOLTAGE)

(a) Turn the ignition switch to the ON position.
(b) Measure the voltage between the terminals of the E8 and E7 ECM connectors.
Standard voltage:

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.
26. 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 ASSEMBLY
OK -- Continue to next step.
27. CHECK VALVE TIMING (CHECK FOR LOOSE AND JUMPED TEETH ON TIMING CHAIN)