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.
| Sensor | Input signal to ECM | ECM function |
| Crankshaft position sensor (POS) | Engine speed | On board diagnosis of misfire |
The misfire detection logic consists of the following two conditions.
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.
A misfire malfunction can be detected on any one cylinder or on multiple cylinders.
| DTC No. | CONSULT screen terms (Trouble diagnosis content) | DTC detecting condition | Possible cause |
| P0300 | MULTI CYL MISFIRE (Random/Multiple cylinder misfire detected) | Multiple cylinder misfire. |
|
| P0301 | CYL 1 MISFIRE (Cylinder 1 misfire detected) | No. 1 cylinder misfires. | |
| P0302 | CYL 2 MISFIRE (Cylinder 2 misfire detected) | No. 2 cylinder misfires. | |
| P0303 | CYL 3 MISFIRE (Cylinder 3 misfire detected) | No. 3 cylinder misfires. | |
| P0304 | CYL 4 MISFIRE (Cylinder 4 misfire detected) | No. 4 cylinder misfires. |
DTC CONFIRMATION PROCEDURE
1.PRECONDITIONING
If DTC Confirmation Procedure has been previously conducted, always perform the following procedure before conducting the next test.
>> GO TO 2.
Is 1st trip DTC detected?
YES >> Proceed to EC-270, "Diagnosis Procedure".
NO >> GO TO 3.
3.PERFORM DTC CONFIRMATION PROCEDURE-2
Hold the accelerator pedal as steady as possible
The similar conditions to (1st trip) Freeze Frame Data means the vehicle operation 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.
| Engine speed | Engine speed in the freeze frame data В± 400 rpm |
| Vehicle speed | Vehicle speed in the freeze frame data В± 10 km/h (6 MPH) |
| Engine coolant temperature (T) condition | When the freeze frame data shows lower than 70В°C (158В°F), T should be lower than 70В°C (158В°F). |
| When the freeze frame data shows higher than or equal to 70В°C (158В°F), T should be higher than or equal to 70В°C (158В°F). |
The time to driving varies according to the engine speed in the freeze frame data.

Is 1st trip DTC detected? YES >> Proceed to EC-270, "Diagnosis Procedure".
NO >> INSPECTION END
Diagnosis Procedure
1.CHECK FOR INTAKE AIR LEAK AND PCV HOSE
Is intake air leak detected? YES >> Discover air leak 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)>>GO TO 3.
YES-2 (
Without CONSULT)>>GO TO 4.
NO >> Repair or replace it.
3.PERFORM POWER BALANCE TEST
With CONSULT
Is the inspection result normal? YES >> GO TO 9.
NO >> GO TO 4.
4.CHECK FUNCTION OF FUEL INJECTOR
Clicking noise should be heard.
Is the inspection result normal? YES >> GO TO 5.
NO >> Perform trouble diagnosis for FUEL INJECTOR. Refer to EC-450, "Diagnosis Procedure".

5.CHECK FUNCTION OF IGNITION COIL-1
CAUTION:
Do the following procedure in the place where ventilation is good without the combustible.
NOTE:
Do not use CONSULT to release fuel pressure, or fuel pressure applies again during the following procedure.
Spark should be generated.

CAUTION:
NOTE:
When the gap is less than 13 mm (0.52 in), the 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-2
Spark should be generated.
Is the inspection result normal? YES >> GO TO 7.
NO >> Check ignition coil, power transistor and their circuits. Refer to EC-456, "Diagnosis Procedure".
7.CHECK SPARK PLUG
Check the initial spark plug for fouling, etc. Refer to EM-45, "Removal and Installation".
Is the inspection result normal? YES >> Replace spark plug(s) with standard type one(s). For spark plug type, refer to EM-118, "Spark Plug".
NO >> 1. Repair or clean spark plug.
2. GO TO 8.

8.CHECK FUNCTION OF IGNITION COIL-3
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 EM-118, "Spark Plug".
9.CHECK COMPRESSION PRESSURE
Check compression pressure. Refer to EM-23, "Inspection".
Is the inspection result normal? YES >> GO TO 10.
NO >> Check pistons, piston rings, valves, valve seats and cylinder head gaskets. Refer to EM-112, "Description".
10.CHECK FUEL PRESSURE
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”. Refer to FL-6, "Exploded View".
NO >> Repair or replace error-detected parts.
12.CHECK IGNITION TIMING
Check ignition timing. Refer to EC-480, "Inspection".
Is the inspection result normal? YES >> GO TO 13.
NO >> Perform “BASIC INSPECTION”. Refer to EC-131, "Work Procedure".
13.CHECK A/F SENSOR 1 INPUT SIGNAL CIRCUIT

*1: Except California
*2: For California

*1: Except California
*2: For California

Is the inspection result normal? YES >> GO TO 14.
NO >> Repair or replace error-detected parts.
14.CHECK A/F SENSOR 1 HEATER
Check the A/F sensor 1 heater. Refer to EC-177, "Component Inspection (A/F Sensor 1 Heater)".
Is the inspection result normal? YES >> GO TO 15.
NO >> Replace A/F sensor 1. Refer to EM-30, "Exploded View".
15.CHECK MASS AIR FLOW SENSOR
With CONSULT
Check “MASS AIRFLOW” in “DATA MONITOR” mode of “ENGINE” using CONSULT.
Specification : EC-486, "Mass Air Flow Sensor"
With GST
Check mass air flow sensor signal in Service $01 with GST.
Specification : EC-486, "Mass Air Flow Sensor"
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 EC-186, "DTC Logic".
16.CHECK SYMPTOM TABLE
Check items on the rough idle symptom in EC-473, "Symptom Table".
Is the inspection result normal? YES >> GO TO 17.
NO >> Repair or replace error-detected parts.
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 EC-55, "Diagnosis Description".
>> GO TO 18.
18.CHECK INTERMITTENT INCIDENT
Perform GI-39, "Intermittent Incident".
>> INSPECTION END
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