13A-DTC P0303: Cylinder 3 Misfire Detected

DTC P0303: Cylinder 3 Misfire Detected

TECHNICAL DESCRIPTION

If a misfire occurs while the engine is running, the engine speed changes for an instant.
The ECM checks for such changes in engine speed.

DESCRIPTIONS OF MONITOR METHODS

Monitor angular acceleration of crankshaft and detect malfunction when negative variation of the angular acceleration is large.

MONITOR EXECUTION

Continuous

MONITOR EXECUTION CONDITIONS (Other monitor and Sensor)

Other Monitor (There is no temporary DTC set in memory for the item monitored below)

Not applicable

Sensor (The sensor below is determined to be normal)

Camshaft position sensor
Mass airflow sensor
Engine coolant temperature sensor
Intake air temperature sensor
Barometric pressure sensor
Throttle position sensor
Fuel tank pressure sensor

DTC SET CONDITIONS

Logic Flow Chart

Check Conditions

Engine speed is between 500 and 4,719 r/min.
Engine coolant temperature is higher than 20°C (68°F).
Barometric pressure is higher than 76 kPa (22.4 in.Hg).
The engine load is with in the positive torque load.
Adaptive learning is complete for the vane which generates a crankshaft position signal.
While the engine is running, excluding sudden acceleration/deceleration and fuel shut-off operation.

Judgment Criterion (change in the angular acceleration of the crankshaft is used for misfire detection)

Misfire counts per 1,000 revolutions exceeds in 2.0 percent.

Check Conditions

Engine speed is between 500 and 4,719 r/min.
Engine coolant temperature is higher than 20°C (68°F).
Barometric pressure is higher than 76 kPa (22.4 in.Hg).
The engine load is with in the positive torque load.
Adaptive learning is complete for the vane which generates a crankshaft position signal.
While the engine is running, excluding sudden acceleration/deceleration and fuel shut-off operation.

Judgment Criterion (change in the angular acceleration of the crankshaft is used for misfire detection)

Misfire has occurred more frequently than allowed during the last 200 revolutions [when the catalyst temperature is higher than 1,000°C (1,832°F)].

FAIL-SAFE AND BACKUP FUNCTION

The supply of fuel to the misfiring cylinder can possibly be cut.

OBD-II DRIVE CYCLE PATTERN

Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 2 .

TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)

Ignition system related part(s) failed.
Low compression pressure.
ECM failed.

DIAGNOSIS

STEP 1. Visual check on ignition spark of No. 3 cylinder.

(1) Remove the spark plug and install it to the ignition coil.

(2) Connect the ignition coil connector.

(3) Remove all injector connector.

(4) At the engine start, check spark plug produces a spark.

Did it spark?

Go to Step 3.

Go to Step 2.

STEP 2. Check the No. 3 cylinder spark plug.

Refer to GROUP 16, Ignition System - On-vehicle Service - Spark Plug Check And Cleaning

Is the spark plug normal?

Refer to Inspection Procedures - Ignition Circuit System

Replace the No. 3 cylinder spark plug. Then go to Step 5.

STEP 3. Check the compression.

Refer to GROUP 11A, On-vehicle Service - Compression Pressure Check

Are there any abnormalities?

Repair or replace it. Then go to Step 5.

Go to Step 4.

STEP 4. Check the trouble symptoms.

(1) Carry out a test drive with the drive cycle pattern. Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 2

(2) Check the diagnostic trouble code (DTC).

Is DTC P0303 set?

Replace the ECM (Refer to Removal and Installation

). Then go to Step 5.

It can be assumed that this malfunction is intermittent. Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions.

STEP 5. Test the OBD-II drive cycle.

(1) Carry out a test drive with the drive cycle pattern. Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 2

(2) Check the diagnostic trouble code (DTC).

Is DTC P0303 set?

Retry the troubleshooting.

The inspection is complete.