how to resolve misfire issues in Toyota Corolla E140 (2006-2013) with code P0301

Solution

1. Preparation

• Gather all required tools and parts.
• Ensure the engine is cool and disconnect the negative battery terminal for safety.
• Tools Required: OBD-II scanner, socket set, torque wrench, multimeter, compression tester.

2. Replace Spark Plug in Cylinder 1

• Remove the ignition coil from cylinder 1 by unscrewing the retaining bolts.
• Disconnect the electrical connector from the ignition coil.
• Remove the spark plug using a spark plug socket and ratchet.
• Inspect the spark plug for wear or damage; replace if necessary.
• Install the new spark plug, torque to manufacturer specifications (typically 13 ft-lbs).
• Reattach the ignition coil and connector.

3. Inspect and Replace Ignition Coil (if necessary)

• Test the ignition coil's resistance using a multimeter; compare readings to manufacturer specs.
• If the coil is faulty, remove it and replace it with a new one.
• Reconnect the electrical connector and ensure it is secured.

4. Check and Clean Fuel Injector for Cylinder 1

• Disconnect the fuel injector connector.
• Remove the fuel rail to access the injector.
• Inspect the fuel injector for clogs or leaks; clean it using an appropriate fuel injector cleaner or replace it if necessary.
• Reinstall the fuel rail and reconnect the injector.

5. Conduct Compression Test on Cylinder 1

• Remove the spark plug from cylinder 1.
• Insert the compression tester into the spark plug hole.
• Crank the engine to take the reading; compare it with manufacturer specifications (typically around 180 psi).
• If the compression is low, further investigation may be needed (e.g., valve issues, head gasket).