my Toyota Highlander XU70 (2020-Present) has a rough start in the morning, what's wrong

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the battery to prevent any electrical issues during repair.

2. Battery Inspection and Replacement

• Sub-steps:
  1. Inspect battery terminals for corrosion and clean them with a wire brush if necessary.
  2. If the battery is weak or old, replace it with a new battery of the same specifications.
• Tools Required: Wrench set, wire brush.

3. Fuel System Check

• Sub-steps:
  1. Connect the fuel pressure gauge to the fuel rail.
  2. Turn the ignition key to the ON position (do not start) to check fuel pressure; it should meet manufacturer specifications (typically around 50-60 PSI).
  3. If the pressure is low, inspect the fuel pump and fuel filter for issues.
• Tools Required: Fuel pressure gauge.

4. Spark Plug Replacement

• Sub-steps:
  1. Remove the ignition coil by unscrewing it from the engine.
  2. Remove the spark plug using a spark plug socket and ratchet.
  3. Inspect the old spark plug for wear; replace it with a new one if necessary (ensure proper gap).
  4. Reinstall the spark plug and ignition coil.
• Tools Required: Spark plug socket, ratchet, torque wrench.
• Note: Torque the spark plugs to manufacturer specifications (usually around 13-15 lb-ft).

5. Air Filter Replacement

• Sub-steps:
  1. Open the air filter housing by unclipping or unscrewing it.
  2. Remove the old air filter and inspect for dirt and debris.
  3. Install a new air filter, ensuring it fits snugly in the housing.
• Tools Required: Screwdriver (if necessary).

6. Coolant Temperature Sensor Check

• Sub-steps:
  1. Locate the coolant temperature sensor (usually near the thermostat).
  2. Disconnect the electrical connector and check resistance with a multimeter while heating the engine.
  3. Replace the sensor if it does not provide the correct resistance readings.
• Tools Required: Multimeter.