how to fix P0301 misfire code in my Toyota Corolla E140 (2006-2013)

Solution

1. Preparation

• Tools Required: OBD-II scanner, socket set, torque wrench, compression gauge, multimeter, fuel injector cleaner.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the negative terminal of the battery to prevent electrical shock.

2. Replace Ignition Components

• Spark Plug Replacement:

  1. Remove the ignition coil by unscrewing the retaining bolts.
  2. Pull the ignition coil off the spark plug.
  3. Remove the old spark plug using a spark plug socket.
  4. Install a new spark plug, ensuring it is gapped correctly (typically around 0.043 inches for this model).
  5. Reattach the ignition coil and torque to manufacturer specifications (usually around 7-10 ft-lbs).

• Ignition Coil Replacement (if necessary):

  1. If the ignition coil shows signs of damage or has been tested faulty, replace it with a new one.
  2. Ensure the new coil is seated properly on the spark plug.

3. Clean or Replace Fuel Injector

• If the fuel injector is clogged:
  1. Remove the fuel injector connector.
  2. Disconnect the fuel rail and remove the injector.
  3. Clean the injector with fuel injector cleaner or replace with a new injector if cleaning does not resolve the issue.
  4. Reinstall the injector and reconnect the fuel rail.

4. Conduct Compression Test

• 1. Remove the spark plug from cylinder 1.
• 1. Insert the compression gauge into the spark plug hole.
• 1. Crank the engine several times and record the compression reading.
• 1. If compression is low (below 120 psi), further diagnostic testing of the cylinder may be necessary.

5. Inspect Vacuum System

• 1. Visually inspect all vacuum hoses attached to the intake manifold for cracks or leaks.
• 1. Use a smoke machine or carburetor cleaner to check for vacuum leaks while the engine is running.
• 1. Repair or replace any damaged vacuum hoses.