how to diagnose a misfire in my Toyota Corolla E140 (2006-2013) with P0302 code?

Solution

1. Preparation

• Gather all necessary tools and parts.
• Disconnect the negative battery cable to ensure safety while working on electrical components.
• Allow the engine to cool before starting work.

2. Replace Spark Plug

1. Remove the engine cover if applicable.
2. Disconnect the ignition coil connector for cylinder 2.
3. Remove the bolts securing the ignition coil and take out the coil.
4. Use a spark plug socket to remove the old spark plug.
5. Inspect the new spark plug and gap it to the manufacturer specifications (typically around 0.043 inches for a Toyota Corolla).
6. Install the new spark plug and torque it to the manufacturer’s specifications (usually around 13 lb-ft).
7. Reinstall the ignition coil and connect the ignition coil connector.

3. Test Ignition Coil

1. Remove the ignition coil from cylinder 2 and visually inspect for any cracks or damage.
2. If necessary, swap the ignition coil with another cylinder (e.g., cylinder 1) and clear the codes.
3. Start the engine and check if the misfire moves to the other cylinder. If it does, replace the ignition coil.

4. Clean or Replace Fuel Injector

1. Disconnect the fuel injector connector for cylinder 2.
2. Remove the fuel rail if needed to access the fuel injector.
3. Inspect the fuel injector for clogs; clean with appropriate injector cleaner or replace if necessary.
4. Reinstall the fuel rail and reconnect all connectors.

5. Verify Compression

1. Remove the spark plug from cylinder 2.
2. Attach the compression tester to the spark plug hole.
3. Crank the engine and record the compression reading.
4. Compare the reading to the manufacturer’s specifications (typically 180-210 psi). If low, further investigation is required for potential internal engine issues.

Tools Required:

• OBD-II scanner
• Torque wrench
• Spark plug socket
• Compression tester
• Basic hand tools (ratchet, sockets)
• Fuel injector cleaner

Parts Required:

• Spark plug (for cylinder 2)
• Ignition coil (if defective)
• Fuel injector (if clogged or defective)

Estimated Repair Time: 2-4 hours

Safety Warnings:

• Disconnect the battery before working on electrical components.
• Allow the engine to cool before performing any maintenance to avoid burns.