my Toyota Highlander Third Generation (2014-2019) engine is misfiring what could be the issue

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the engine to cool before beginning work.

2. Replace Spark Plugs

• Tools Required: Socket set, torque wrench, spark plug socket.
• Remove the ignition coils by unbolting and disconnecting electrical connectors.
• Using the spark plug socket, carefully remove the old spark plugs.
• Install new spark plugs, ensuring the gap is set to the manufacturer's specifications (typically around 0.043 inches for many Toyota engines).
• Torque the spark plugs to the manufacturer's specified value (usually around 13 lb-ft).

3. Test/Replace Ignition Coils

• Tools Required: Multimeter.
• Connect the multimeter to the ignition coil terminals and test for resistance.
• If readings are outside the specified range (refer to service manual), replace the faulty ignition coil.
• Reinstall the ignition coils and reconnect electrical connectors.

4. Check/Replace Fuel Injectors

• Tools Required: Fuel pressure gauge, injector cleaning kit (if cleaning is necessary).
• Attach the fuel pressure gauge to the fuel rail and check for proper fuel pressure according to specifications (typically around 50-60 psi).
• If pressure is low, inspect the fuel pump and filter.
• If injectors are clogged, use an injector cleaning kit or replace them as necessary.

5. Compression Test (if needed)

• Tools Required: Compression tester.
• Remove spark plugs and insert the compression tester into each cylinder.
• Crank the engine and record the pressure readings.
• Compare results to specifications (usually around 150-200 psi); low readings indicate potential internal engine issues.