my Toyota Corolla E210 (2019-2024) has a rough idle when I start it, what's causing it?

Solution

1. Preparation

• Tools Required: OBD-II scanner, fuel pressure gauge, multimeter, socket set, torque wrench, cleaning supplies (throttle body cleaner, rags).
• Disconnect the negative battery terminal to ensure safety while working on electrical components.

2. Clean Throttle Body

• Remove the air intake duct connected to the throttle body using the appropriate socket size.
• Spray throttle body cleaner into the throttle body while opening the throttle plate manually to clean any carbon deposits.
• Wipe clean with a rag, ensuring no residue remains. Reinstall the intake duct and secure it properly.

3. Replace Spark Plugs

• Remove the ignition coil by unscrewing the bolts and pulling it out of the spark plug well.
• Use a spark plug socket to remove the old spark plugs.
• Inspect and replace with new spark plugs, ensuring they are gapped correctly as per manufacturer specifications (typically around 0.043 inches).
• Reinstall ignition coils and secure them with the bolts to the specified torque (usually around 10-15 ft-lbs).

4. Check Fuel System

• Connect the fuel pressure gauge to the fuel rail test port.
• Turn the ignition to the "ON" position without starting the engine to check the fuel pressure reading (should be around 43-50 psi for most models).
• If pressure is low, inspect the fuel pump and fuel filter for potential issues, replacing as necessary.

5. Reconnect Battery

• Reconnect the negative battery terminal once all components are secured and the work area is clear.
• Start the engine to check for improvements in idle quality.