how to diagnose a misfire on my Toyota Corolla E170 (2013-2019) with P0302 code

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the engine to cool down if it has been running recently.

2. Inspect and Replace Spark Plug

• Tools Required: Socket set, torque wrench, spark plug socket.
• Remove the ignition coil from cylinder 2.
• Remove the spark plug from cylinder 2 using a spark plug socket.
• Inspect the spark plug for wear or damage; replace it if necessary.
• Install the new spark plug and torque it to the manufacturer's specifications (typically around 13-16 lb-ft).
• Reinstall the ignition coil.

3. Check and Replace Ignition Coil

• If the spark plug is in good condition but misfire persists, test the ignition coil.
• Tools Required: Multimeter (for testing), socket set.
• Remove the ignition coil for cylinder 2.
• Test the coil using a multimeter to check for proper resistance; replace the coil if it is out of specification.
• Reinstall the new ignition coil.

4. Inspect and Clean Fuel Injector

• If the ignition components are not the issue, inspect the fuel injector.
• Tools Required: Fuel injector cleaner, socket set.
• Remove the fuel injector for cylinder 2.
• Use fuel injector cleaner to clean the injector; if it is damaged, replace it with a new one.
• Reinstall the fuel injector and ensure proper connection.

5. Verify Compression

• If the misfire continues, perform a compression test.
• Tools Required: Compression tester.
• Remove the spark plug from cylinder 2 and connect the compression tester.
• Crank the engine and record the compression reading; compare it to specifications (typically 180-200 psi).
• If compression is low, further engine diagnostics may be necessary.