how to fix a misfire in my Toyota Camry XV50 (2012-2017) with a P0300 code

Solution

1. Preparation

• Gather all necessary tools and parts.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the negative terminal of the battery.

2. Inspect and Replace Spark Plugs

• Sub-steps:
  1. Remove the ignition coil harness connectors from each cylinder.
  2. Unscrew and remove the ignition coils using a socket set.
  3. Remove the spark plugs using a spark plug socket and ratchet.
  4. Inspect the spark plugs for wear; replace with OEM-spec spark plugs if necessary.
  5. Gap the new spark plugs according to manufacturer specifications.
  6. Reinstall the spark plugs and ignition coils, tightening to the manufacturer’s torque specifications (usually around 13 ft-lbs).

3. Inspect and Replace Ignition Coils

• Sub-steps:
  1. After removing the ignition coils, test each coil with a multimeter for resistance (consult service manual for specs).
  2. Replace any faulty ignition coils with OEM parts.
  3. Reinstall the new ignition coils and their connectors.

4. Inspect Fuel System

• Sub-steps:
  1. Disconnect the fuel pump relay and start the engine to relieve fuel pressure.
  2. Reconnect the fuel pump relay and attach a fuel pressure gauge to the fuel rail.
  3. Turn the ignition to the "ON" position (do not start) to check for correct fuel pressure (usually around 40-50 psi).
  4. If pressure is low, check the fuel filter, fuel pump, and fuel lines for blockages or damage.
  5. Clean or replace fuel injectors if clogs are found.

5. Check for Vacuum Leaks

• Sub-steps:
  1. Visually inspect all vacuum hoses connected to the intake manifold.
  2. Use a smoke machine or carburetor cleaner to identify leaks.
  3. Replace any damaged hoses or seals as necessary.

6. Verify Engine Compression

• Sub-steps:
  1. Remove spark plugs and injectors to prevent flooding.
  2. Use a compression tester on each cylinder and record the readings.
  3. If a cylinder shows low compression, further investigation may be required (valves, piston rings).