P0300

DTC P0300 - P0308 MULTIPLE CYLINDER MISFIRE, NO. 1 - 8 CYLINDER 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 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.

On Board Diagnosis Logic:

DTC Confirmation Procedure

CAUTION:
Always drive vehicle in safe manner according to traffic conditions and obey all traffic laws when driving.
1. If DTC Confirmation Procedure has been previously conducted, always perform the following procedure before conducting the next test.
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.
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 approximately 15 minutes.
7. Check 1st trip DTC.
8. If 1st trip DTC is detected, go to P0300.

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 means that the following conditions should be satisfied at the same time.





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









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.
OK or NG
OK - GO TO 2.
NG - Discover air leakage 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 CONSULT-III) GO TO 3.
OK (Without CONSULT-III GO TO 4.
NG - Repair or replace malfunctioning part.
3.PERFORM POWER BALANCE TEST
With CONSULT-III
1. Start engine and warm it up to normal operating temperature.
2. Perform "POWER BALANCE" in "ACTIVE TEST" mode with CONSULT-III.
3. Is there any cylinder which does not produces a momentary engine speed drop?
Yes or No
Yes - GO TO 4.
No - GO TO 9.
4.CHECK FUNCTION OF FUEL INJECTOR
Without CONSULT-III
1. Start engine and warm it up to normal operating temperature.





2. Listen to fuel injector operating sound.

Operating sound should exist.

OK or NG
OK - GO TO 5.
NG - Perform trouble diagnosis for fuel injector, refer to 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 (1) in IPDM E/R (2) 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 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 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 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 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 is made.

NOTE:
When the gap is less than 13 mm, spark might be generated even if the coil is malfunctioning.
OK or NG
OK - GO TO 9.
NG - 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.

OK or NG
OK - GO TO 7.
NG - Check ignition coil, power transistor and their circuits. Refer to Diagnosis Procedure.
7.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 [1][2]Specifications.
NG - 1. Repair or clean spark plug.
2. GO TO 8.
8.CHECK FUNCTION OF IGNITION COIL-III
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.

OK or NG
OK INSPECTION END
NG - Replace spark plug(s) with standard type one(s). For spark plug type, refer to [1][2]Specifications.
9.CHECK COMPRESSION PRESSURE
Check compression pressure. Refer to Testing and Inspection.
OK or NG
OK - GO TO 10.
NG - 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 Testing and Inspection.
3. Install fuel pressure gauge and check fuel pressure. Refer to Testing and Inspection.

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

OK or NG
OK - GO TO 12.
NG - GO TO 11.
11.DETECT MALFUNCTIONING PART
Check the following.
- Fuel pump and circuit (Refer to Diagnosis Procedure.)
- Fuel pressure regulator (Refer to Testing and Inspection.)
- Fuel lines
- Fuel filter for clogging
Repair or replace malfunctioning part.
12.CHECK IGNITION TIMING
Check the following items. Refer to Basic Service Procedure.





OK or NG
OK - GO TO 13.
NG - Follow the Basic Service Procedure.
13.CHECK AIR FUEL RATIO (A/F) SENSOR 1 INPUT SIGNAL CIRCUIT
1. Turn ignition switch OFF.
2. Disconnect corresponding air fuel ratio (A/F) sensor 1 harness connector.





3. Disconnect ECM harness connector.
4. Check harness continuity between the following terminals. Refer to Wiring Diagram.






Continuity should exist.


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











Continuity should not exist.


6. Also check harness for short to power.
OK or NG
OK - GO TO 14.
NG - Repair open circuit or short to ground or short to power in harness or connectors.
14.CHECK A/F SENSOR 1 HEATER
Refer to P0031.
OK or NG
OK - GO TO 16.
NG - GO TO 15.
15.REPLACE AIR FUEL RATIO (A/F) SENSOR 1
Replace malfunctioning A/F sensor 1.

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 Oxygen Sensor Thread
Cleaner [commercial service tool (J-43897-18 or J-43897-12)] and approved Anti-seize Lubricant
(commercial service tool).
INSPECTION END
16.CHECK MASS AIR FLOW SENSOR
With CONSULT-III
1. Start engine and warm it up to normal operating temperature.
2. Check "MASS AIRFLOW" in "DATA MONITOR" mode with CONSULT-III.

2.0 - 6.0 g�m/sec: at idling
7.0 - 20.0 g�m/sec: at 2,500 rpm

With GST
1. Start engine and warm it up to normal operating temperature.
2. Check mass air flow sensor signal in Service $01 with GST.

2.0 - 6.0 g�m/sec: at idling
7.0 - 20.0 g�m/sec: at 2,500 rpm

OK or NG
OK - GO TO 17.
NG - Check connectors for rusted terminals or loose connections in the mass air flow sensor circuit or ground. Refer to P0101.
17.CHECK SYMPTOM MATRIX CHART
Check items on the rough idle symptom in Symptom Related Diagnostic Procedures.
OK or NG
OK - GO TO 18.
NG - Repair or replace malfunctioning part.
18.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.
GO TO 19.
19.CHECK INTERMITTENT INCIDENT
Refer to Diagnosis Procedure.
INSPECTION END