how to fix P0300 misfire in Toyota Corolla E140 (2006-2013)

Solution

1. Preparation

• Gather required tools and parts.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the battery to prevent electrical shock.

2. Replace Spark Plugs

• Tools Required: Socket set, torque wrench, gap gauge
• Remove the ignition coils from the spark plugs by unscrewing the retaining bolts.
• Carefully pull out the spark plugs using a spark plug socket.
• Inspect the old plugs and ensure the new ones are gapped correctly according to manufacturer specifications.
• Install the new spark plugs and torque them to the recommended specification (usually around 13-16 lb-ft).
• Reattach the ignition coils and secure them with bolts.

3. Inspect and Replace Ignition Coils (if necessary)

• Tools Required: Socket set, multimeter or coil tester
• Disconnect the electrical connectors from the ignition coils.
• Remove the ignition coils from the engine by unscrewing the retaining bolts.
• Test each ignition coil with a multimeter or coil tester to ensure they are functioning properly (check resistance values according to specifications).
• Replace any faulty ignition coils with new ones, securing them with bolts and reconnecting the electrical connectors.

4. Clean or Replace Fuel Injectors

• Tools Required: Fuel injector cleaner kit, socket set
• If injectors are clogged, use a fuel injector cleaning kit to clean them according to the manufacturer’s instructions.
• If they are damaged or leaking, remove them by unscrewing the retaining clips and disconnecting the fuel lines.
• Install new or cleaned injectors by securing them in place and reconnecting the fuel lines.

5. Check for Vacuum Leaks

• Tools Required: Smoke machine or carburetor cleaner
• Inspect all vacuum lines and intake manifold gaskets for cracks or leaks.
• Use a smoke machine to detect leaks or spray carburetor cleaner around suspected areas and listen for changes in engine idle.
• Replace any damaged vacuum hoses or gaskets as needed.

6. Perform a Compression Test

• Tools Required: Compression tester
• Remove all spark plugs to allow for accurate compression measurement.
• Insert the compression tester into each cylinder and crank the engine.
• Record the readings and compare with manufacturer specifications (typically around 180-200 psi).
• If compression is low in any cylinder, further investigation is needed (possible valve or piston issues).