P0303

P0300, P0301, P0302, P0303, P0304, P0305, P0306 Misfire

On Board Diagnosis Logic

When a misfire occurs, engine speed will fluctuate. If the engine speed fluctuates enough to cause the crankshaft position (CKP) sensor (POS) signal to vary, ECM can determine that a misfire is occurring.





The misfire detection logic consists of the following two conditions.
1) One Trip Detection Logic (Three Way Catalyst Damage)

On the first trip, when a misfire condition occurs that can damage the three way catalyst (TWC) due to overheating, the MIL will blink.

When a misfire condition occurs, the ECM monitors the CKP sensor signal every 200 engine revolutions for a change.

When the misfire condition decreases to a level that will not damage the TWC, the MIL will turn off.

If another misfire condition occurs that can damage the TWC on a second trip, the MIL will blink.

When the misfire condition decreases to a level that will not damage the TWC, the MIL will remain on.

If another misfire condition occurs that can damage the TWC, the MIL will begin to blink again.
2) Two Trip Detection Logic (Exhaust quality deterioration)

For misfire conditions that will not damage the TWC (but will affect vehicle emissions), the MIL will only light when the misfire is detected on a second trip. During this condition, the ECM monitors the CKP sensor signal every 1,000 engine revolutions.

A misfire malfunction can be detected in any one cylinder or in multiple cylinders.






DTC Confirmation Procedure

CAUTION:

Always drive vehicle in safe manner according to traffic conditions and obey all traffic laws when driving.

NOTE:

If DTC Confirmation Procedure has been previously conducted, always perform the following procedure before conducting the next step.

3) Turn ignition switch OFF and wait at least 10 seconds.
4) Turn ignition switch ON.
5) Turn ignition switch OFF and wait at least 10 seconds.

with SDT

1) Turn ignition switch ON, and select "Data list" mode with SDT.
2) Start engine and warm it up to normal operating temperature.
3) Turn ignition switch OFF and wait at least 10 seconds.
4) Turn ignition switch ON.
5) Turn ignition switch OFF and wait at least 10 seconds.
6) Restart engine and let it idle for about 15 minutes.
7) Check 1st trip DTC.
8) If 1st trip DTC is detected, go to "Diagnosis Procedure".

NOTE:
If 1st trip DTC is not detected during above procedure, performing the following procedure is advised.

a) Turn ignition switch OFF and wait at least 10 seconds.
b) Turn ignition switch ON.
c) Turn ignition switch OFF and wait at least 10 seconds.
d) Start engine and drive the vehicle under similar conditions to (1st trip) Freeze Frame Data for a certain time. Refer to the table below.
Hold the accelerator pedal as steady as possible.
Similar conditions to (1st trip) Freeze Frame Data mean that the following conditions should be satisfied at the same time.






Driving time varies according to the engine speed in the freeze frame data.






with GST

Follow the procedure "WITH SDT" above.

Diagnosis Procedure

1. CHECK FOR INTAKE AIR LEAK AND PCV HOSE

1 Start engine and run it at idle speed.
2 Listen for the sound of the intake air leak.
3 Check PCV hose connection.

OK or NG
OK
GO TO 2.
NG
Discover air leak location and repair.

2. CHECK FOR EXHAUST SYSTEM CLOGGING

Stop engine and visually check exhaust tube, three way catalyst and muffler for dents.

OK or NG
OK (With SDT)
GO TO 3.
OK (Without SDT)
GO TO 4.
NG
ERROR! Unknown action!Repair or replace it.

3. PERFORM POWER BALANCE TEST

With SDT
1 Perform "POWER BALANCE" in "Active test" mode.
2 Is there any cylinder which does not produce a momentary engine speed drop?

Yes or No
Yes
GO TO 4.
No
GO TO 10.

4. CHECK FUNCTION OF FUEL INJECTOR-I

Stop engine.
1 Disconnect harness connector F44 (3), F201 (1)











2 Turn ignition switch ON.
3 Check voltage between harness connector F44 terminal 3 and ground with SDT or tester.











4 Turn ignition switch OFF.
5 Disconnect ECM harness connector.
6 Check harness continuity between harness connector F44 and ECM as follows.
Refer to Wiring Diagram.










7 Also check harness for short to ground and short to power.

OK or NG
OK
GO TO 5.
NG
Perform trouble diagnosis for FUEL INJECTOR, refer to [Fuel Injector Circuit Check] Testing and Inspection.

5. CHECK FUNCTION OF FUEL INJECTOR-II

Provide battery voltage between harness connector F201 as follows and then interrupt it. Listen to each fuel injector operating sound.















OK or NG
OK
GO TO 6.
NG
Perform trouble diagnosis for FUEL INJECTOR, refer to [Fuel Injector Circuit Check] Testing and Inspection.

6. CHECK FUNCTION OF FUEL INJECTOR-III

1 Reconnect all harness connector disconnected.
2 Start engine.
3 Listen to fuel injectors No. 2, No. 4, No.6 operating sound.











OK or NG
OK
GO TO 7.
NG
Perform trouble diagnosis for FUEL INJECTOR, refer to [Fuel Injector Circuit Check] Testing and Inspection.

7. CHECK FUNCTION OF IGNITION COIL-I

CAUTION:
Perform the following procedure in a place with no combustible objects and good ventilation.

1 Turn ignition switch OFF.
2 Remove fuel pump fuse (No.48) in IPDM E/R to release fuel pressure.






NOTE:
Do not use SDT to release fuel pressure, or fuel pressure applies again during the following procedure.

3 Start engine.
4 After engine stalls, crank it two or three times to release all fuel pressure.
5 Turn ignition switch OFF.
6 Remove all ignition coil harness connectors to avoid the electrical discharge from the ignition coils.
7 Remove ignition coil and spark plug of the cylinder to be checked.
8 Crank engine for five seconds or more to remove combustion gas in the cylinder.
9 Connect spark plug and harness connector to ignition coil.
10 Fix ignition coil using a rope etc. with gap of 13 - 17 mm (0.52 - 0.66 in) between the edge of the spark plug and grounded metal portion as shown in the figure.





11 Crank engine for about three seconds, and check whether spark is generated between the spark plug and the grounded metal portion.






CAUTION:
- Never place to the spark plug and the ignition coil within 50 cm (19.7 in) each other. Be careful not to get an electrical shock while checking, because the electrical discharge voltage becomes 20 kV or more.
- It might cause to damage the ignition coil if the gap of more than 17 mm (0.66 in) is made.

NOTE:
When the gap is less than 13 mm (0.52 in), the spark might be generated even if the coil is malfunctioning.

OK or NG
OK
GO TO 11.
NG
GO TO 8.

8. CHECK FUNCTION OF IGNITION COIL-II

1 Turn ignition switch OFF.
2 Disconnect spark plug and connect a known-good spark plug.
3 Crank engine for about three seconds, and recheck whether spark is generated between the spark plug and the grounded metal portion.






OK or NG
OK
GO TO 9.
NG
Check ignition coil, power transistor and their circuits. Refer to [Ignition Signal Circuit Check] Testing and Inspection.

9. CHECK SPARK PLUG

Check the initial spark plug for fouling, etc.






OK or NG
OK
Replace spark plug(s) with standard type one(s). For spark plug type, refer to [Spark Plug: Removal and Installation] Removal and Installation.
NG
1 Repair or clean spark plug.
2 GO TO 10.

10. CHECK FUNCTION OF IGNITION COIL-III

1 Reconnect the initial spark plugs.
2 Crank engine for about three seconds, and recheck whether spark is generated between the spark plug and the grounded portion.






OK or NG
OK
INSPECTION END
NG
Replace spark plug(s) with standard type one(s). For spark plug type, refer to [Spark Plug: Removal and Installation] Removal and Installation.

11. CHECK COMPRESSION PRESSURE

Check compression pressure. Refer to [Compression Pressure] Testing and Inspection.

OK or NG
OK
GO TO 12.
NG
Check pistons, piston rings, valves, valve seats and cylinder head gaskets.

12. CHECK FUEL PRESSURE

1 Install all removed parts.
2 Release fuel pressure to zero. Refer to [Fuel Pressure Check: VQ40DE] Testing and Inspection.
3 Install fuel pressure gauge and check fuel pressure. Refer to [Fuel Pressure Check: VQ40DE] Testing and Inspection.






OK or NG
OK
GO TO 14.
NG
GO TO 13.

13. DETECT MALFUNCTIONING PART

Check the following.
- Fuel pump and circuit (Refer to [Fuel Pump Circuit Check] Testing and Inspection.)
- Fuel pressure regulator (Refer to [Fuel Pressure Check: VQ40DE] Testing and Inspection.)
- Fuel lines
- Fuel filter for clogging


Repair or replace.

14. CHECK IGNITION TIMING

Check the following items. Refer to [Basic Inspection] Basic Inspection.






OK or NG
OK
GO TO 15.
NG
Follow the [Basic Inspection] Basic Inspection.

15. CHECK A/F SENSOR 1 INPUT SIGNAL

1 Turn ignition switch OFF.
2 Disconnect A/F sensor 1 harness connector.





3 Disconnect ECM harness connector.
4 Check harness continuity between A/F sensor 1 terminal and ECM terminal as follows.
Refer to Wiring Diagram.










5 Check harness continuity between the following terminals and ground.
Refer to Wiring Diagram.










6 Also check harness for short to power.

OK or NG
OK
GO TO 16.
NG
Repair open circuit or short to ground or short to power in harness or connectors between ECM and A/F sensor 1.

16. CHECK A/F SENSOR 1 HEATER

Refer to [P0031, P0032, P0051, P0052 A/F Sensor 1 Heater] P0031.

OK or NG
OK
GO TO 18.
NG
GO TO 17.

17. REPLACE A/F SENSOR 1

Replace malfunctioning A/F sensor 1. Refer to [Exhaust Manifold and Three Way Catalyst: Exploded View [VQ40DE] Exhaust Manifold and Three Way Catalyst Exploded View ].

CAUTION:
- Discard any A/F sensor which has been dropped from a height of more than 0.5 m (19.7 in) onto a hard surface such as a concrete floor; use a new one.
- Before installing new A/F sensor, clean exhaust system threads using Heated Oxygen Sensor Thread Cleaner tool J-43897-18 or J-43897-12 and approved anti-seize lubricant.


INSPECTION END

18. CHECK MASS AIR FLOW SENSOR

With SDT

Check mass air flow sensor signal in "Data list" mode with SDT.






With GST

Check mass air flow sensor signal in Service $01 with GST.






OK or NG
OK
GO TO 19.
NG
Check connectors for rusted terminals or loose connections in the mass air flow sensor circuit or ground. Refer to [P0101 MAF Sensor] P0101.

19. CHECK SYMPTOM MATRIX CHART

Check items on the rough idle symptom in [Engine Control System Symptoms: Symptom Matrix Chart] Symptom Related Diagnostic Procedures.

OK or NG
OK
GO TO 20.
NG
Repair or replace.

20. ERASE THE 1ST TRIP DTC

Some tests may cause a 1st trip DTC to be set.

Erase the 1st trip DTC from the ECM memory after performing the tests. Refer to [On Board Diagnosis Function] On Board Diagnosis Function (Without SDT) or [SDT Function] SDT Function (With SDT).


GO TO 21.

21. CHECK INTERMITTENT INCIDENT

Refer to [Service Information for Electrical Incident: Work Flow] Service Information for Electrical Incident: Work Flow.


INSPECTION END