how to diagnose and fix a misfire in my Toyota Tacoma N300 (2016-Present)

Learn how to diagnose and fix P0300-P0306 engine misfire in Toyota Tacoma N300. Step-by-step guide with diagnostic procedures and repair instructions.

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Disconnect the negative battery terminal to prevent electrical shock.
• Ensure the vehicle is parked on a level surface and the engine is cool.

2. Replace Spark Plugs

• Tools Required: Socket set, Torque wrench, Spark plug gap tool
• Remove the engine cover (if applicable) to access the spark plugs.
• Disconnect the ignition coil connectors and remove the bolts securing the coils.
• Carefully pull out the ignition coils and set them aside.
• Use a spark plug socket to remove old spark plugs.
• Inspect and gap new spark plugs as per manufacturer specifications (typically 0.043 inches for Toyota).
• Install the new spark plugs and torque them to the manufacturer’s specifications (usually around 13 lb-ft).
• Reinstall the ignition coils and reconnect the connectors.

3. Inspect and Replace Ignition Coils (if necessary)

• Tools Required: Socket set, Multimeter
• Test each ignition coil with a multimeter for resistance (check manufacturer specs).
• If any coils are out of spec, replace them with new units.
• Reassemble components as previously detailed.

4. Clean or Replace Fuel Injectors

• Tools Required: Fuel injector cleaner kit or replacement injectors
• If injectors are clogged, use an injector cleaning kit or replace them.
• Reinstall fuel injectors ensuring proper seating and connection.

5. Check Fuel Pressure

• Tools Required: Fuel pressure gauge
• Connect the fuel pressure gauge to the fuel rail.
• Turn the ignition to the "ON" position (without starting the engine) and check the pressure reading.
• If pressure is below specifications, inspect the fuel pump and filter for issues.

6. Perform Compression Test (if necessary)

• Tools Required: Compression tester
• Remove all spark plugs and connect the compression tester to the first cylinder.
• Crank the engine several times and record the reading.
• Repeat for all cylinders, comparing results. Low readings may indicate valve or piston issues.