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

DTC Logic

DTC DETECTION 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.

1. One Trip Detection Logic (Three Way Catalyst Damage) On the 1st 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 illuminate 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.

1. Turn ignition switch OFF and wait at least 10 seconds.
2. Turn ignition switch ON.
3. Turn ignition switch OFF and wait at least 10 seconds. >> GO TO 2.

2.PERFORM DTC CONFIRMATION PROCEDURE-I

1. Start engine and warm it up to normal operating temperature.
2. Turn ignition switch OFF and wait at least 10 seconds.
3. Turn ignition switch ON.
4. Turn ignition switch OFF and wait at least 10 seconds.
5. Restart engine and let it idle for approximately 15 minutes.
6. Check 1st trip DTC. Is 1st trip DTC detected?

YES >> Go to Diagnosis Procedure.
NO >> GO TO 3.
3.PERFORM DTC CONFIRMATION PROCEDURE-II

1. Turn ignition switch OFF and wait at least 10 seconds.
2. Turn ignition switch ON.
3. Turn ignition switch OFF and wait at least 10 seconds.
4. 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.

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

5. Check 1st trip DTC. Is 1st trip DTC detected?

YES >> Go to Diagnosis Procedure.
NO >> Inspection END

Diagnosis Procedure
1.CHECK FOR INTAKE AIR LEAKAGE AND PCV HOSE

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

YES >> Discover air leakage location and repair.
NO >> GO TO 2.
2.CHECK FOR EXHAUST SYSTEM CLOGGING
Stop engine and visually check exhaust tube, three way catalyst and muffler for dents.
Is the Inspection result normal?
YES-1 >> With CONSULT-III: GO TO 3.
YES-2 >> Without CONSULT-III: GO TO 4.
NO >> Repair or replace malfunctioning part.
3.PERFORM POWER BALANCE TEST
With CONSULT-III

1. Start engine.
2. Perform "POWER BALANCE" in "ACTIVE TEST" mode with CONSULT-III.
3. Check that each circuit produces a momentary engine speed drop. Is the Inspection result normal?

YES >> GO TO 9.
NO >> GO TO 4.
4.CHECK FUNCTION OF FUEL INJECTOR

1. Start engine and let it idle.

2. Listen to each fuel injector operation.

Clicking sound should be heard.

Is the Inspection result normal?
YES >> GO TO 5.
NO >> Perform trouble diagnosis for FUEL INJECTOR, refer to See: Powertrain Management\Fuel Delivery and Air Induction\Fuel Injector\Testing and Inspection\Diagnosis Procedure.
5.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 in IPDM E/R to release fuel pressure.

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

3. Start engine.
4. After engine stalls, crank it 2 or 3 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 5 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 approximately 3 seconds, and check whether spark is generated between the spark plug and the grounded metal portion.

Spark should be generated.

CAUTION:

• Never place 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 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), a spark might be generated even if the coil is malfunctioning.
Is the Inspection result normal?
YES >> GO TO 9.
NO >> GO TO 6.
6.CHECK FUNCTION OF IGNITION COIL-II

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

Spark should be generated.

Is the Inspection result normal?
YES >> GO TO 7.
NO >> Check ignition coil, power transistor and their circuits. Refer to See: Powertrain Management\Ignition System\Testing and Inspection\Ignition Signal\Diagnosis Procedure.
7.CHECK SPARK PLUG

1. Reconnect the initial spark plugs.
2. Crank engine for approximately 3 seconds, and recheck whether spark is generated between the spark plug and the grounded portion.

Spark should be generated.

Is the Inspection result normal?
YES >> Inspection END
NO >> Replace spark plug(s) with standard type one(s). For spark plug type, refer to See: Engine, Cooling and Exhaust\Engine\Spark Plug\Service and Repair.
9.CHECK COMPRESSION PRESSURE
Check compression pressure. Refer to See: Engine, Cooling and Exhaust\Engine\Compression Check\Testing and Inspection.
Is the Inspection result normal?
YES >> GO TO 10.
NO >> Check pistons, piston rings, valves, valve seats and cylinder head gaskets.
10.CHECK FUEL PRESSURE

1. Install all removed parts.
2. Release fuel pressure to zero. Refer to See: Engine, Cooling and Exhaust\Engine\Fuel Pressure\Testing and Inspection.
3. Install fuel pressure gauge kit [SST (J-44321)] and check fuel pressure. Refer to See: Engine, Cooling and Exhaust\Engine\Fuel Pressure\Testing and Inspection.

At idle: Approximately 350 kPa (3.57 kg/cm2, 51 psi)

Is the Inspection result normal?
YES >> GO TO 12.
NO >> GO TO 11.
11.DETECT MALFUNCTIONING PART
Check fuel hoses and fuel tubes for clogging.
Is the Inspection result normal?
YES >> Replace "fuel filter and fuel pump assembly".
NO >> Repair or replace malfunctioning part.
12.CHECK IGNITION TIMING
Check idle speed and ignition timing.
For procedure, refer to See: Powertrain Management\Computers and Control Systems\Testing and Inspection\Programming and Relearning\Basic Inspection.
For specification, refer to See: Engine, Cooling and Exhaust\Engine\Idle Speed\Specifications and See: Engine, Cooling and Exhaust\Engine\Ignition Timing\Specifications.
Is the Inspection result normal?
YES >> GO TO 13.
NO >> Follow the See: Powertrain Management\Computers and Control Systems\Testing and Inspection\Programming and Relearning\Basic Inspection.
13.CHECK A/F SENSOR 1 INPUT SIGNAL CIRCUIT

1. Turn ignition switch OFF.
2. Disconnect corresponding A/F sensor 1 harness connector.
3. Disconnect ECM harness connector.
4. Check the continuity between A/F sensor 1 harness connector and ECM harness connector.

5. Check the continuity between A/F sensor 1 harness connector and ground, or ECM harness connector and ground.

6. Also check harness for short to power. Is the Inspection result normal?

YES >> GO TO 14.
NO >> Repair open circuit, short to ground or short to power in harness or connectors.
14.CHECK A/F SENSOR 1 HEATER
Refer to See: P0031.
Is the Inspection result normal?
YES >> GO TO 15.
NO >> Replace malfunctioning A/F sensor 1.
15.CHECK MASS AIR FLOW SENSOR
With CONSULT-III

1. Check "MASS AIR FLOW" in "DATA MONITOR" mode with CONSULT-III.
2. For specification, refer to See: Powertrain Management\Computers and Control Systems\Air Flow Meter/Sensor\Specifications. With GST

1. Check mass air flow sensor signal in Service $01 with GST.
2. For specification, refer to See: Powertrain Management\Computers and Control Systems\Air Flow Meter/Sensor\Specifications. Is the measurement value within the specification?

YES >> GO TO 16.
NO >> Check connectors for rusted terminals or loose connections in the mass air flow sensor circuit or ground. Refer to See: P0102.
16.CHECK SYMPTOM TABLE
Check items on the rough idle symptom in See: Powertrain Management\Computers and Control Systems\Testing and Inspection\Symptom Related Diagnostic Procedures.
Is the Inspection result normal?
YES >> GO TO 17.
NO >> Repair or replace malfunctioning part.
17.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 See: Powertrain Management\Computers and Control Systems\Testing and Inspection\Scan Tool Testing and Procedures\On Board Diagnostic (OBD) System\Diagnosis Description.
>> GO TO 18.
18.CHECK INTERMITTENT INCIDENT
Refer to See: Testing and Inspection\Initial Inspection and Diagnostic Overview\Service Information For Electrical Incident\Intermittent Incident.
>> Inspection END