my Toyota Highlander Third Generation (2014-2019) has a rough start and misfires

Solution

1. Preparation

• Gather tools and parts: OBD-II scanner, socket set, torque wrench, fuel pressure gauge, new spark plugs, new ignition coils (if needed), and cleaning supplies.
• Disconnect the negative battery terminal to prevent electrical shorts.

2. Replace Spark Plugs

1. Remove engine cover (if applicable) using a socket set.
2. Disconnect ignition coil connectors from the coils.
3. Remove ignition coils from the spark plugs.
4. Use a spark plug socket to remove old spark plugs.
5. Inspect the new spark plugs for proper gap settings and install them into the engine.
6. Reinstall ignition coils and reconnect connectors.
7. Reinstall engine cover.

3. Inspect and Replace Ignition Coils (if needed)

1. If misfire codes indicate specific cylinders, replace corresponding ignition coils.
2. Remove the ignition coil from the affected cylinder by unscrewing it.
3. Install the new ignition coil and secure it with the appropriate torque (check manufacturer specs).
4. Reconnect the ignition coil connector.

4. Fuel System Inspection

1. Connect a fuel pressure gauge to the fuel rail.
2. Turn the ignition to the "on" position (without starting the engine) and check the fuel pressure reading against manufacturer specifications.
3. If pressure is low, check the fuel pump and fuel filter for blockages or damage.
4. If needed, replace the fuel filter or fuel pump according to manufacturer specifications.

5. Clean or Replace Fuel Injectors

1. If fuel injectors are clogged, remove them from the engine.
2. Clean the injectors using a dedicated injector cleaning solution or replace them if severely damaged.
3. Reinstall injectors and ensure proper seating and connection.