how to diagnose a misfire in my Toyota RAV4 Fifth Generation (2019-present)

Solution

1. Preparation

• Gather tools and necessary parts.
• Disconnect the negative battery terminal to ensure safety.
• Allow the engine to cool down before beginning work.

2. Inspect and Replace Spark Plugs

• Sub-steps:
  • Remove the ignition coils by unscrewing the retaining bolts and disconnecting the electrical connectors.
  • Use a spark plug socket and ratchet to remove the spark plugs.
  • Inspect the spark plugs for signs of wear or fouling; replace if necessary.
  • Install new spark plugs, ensuring proper gap settings (typically 0.043 inches for the RAV4). Torque to manufacturer's specifications (approx. 13 lb-ft).
  • Reinstall the ignition coils in reverse order.

3. Check and Replace Ignition Coils

• Sub-steps:
  • If misfire codes point to specific cylinders, test the ignition coils using a multimeter to check for proper resistance.
  • Replace any faulty ignition coils with OEM parts, ensuring correct installation.
  • Reconnect electrical connectors and secure the coils properly.

4. Examine Fuel System

• Sub-steps:
  • Use a fuel pressure gauge to check fuel pressure against specifications (approximately 50-60 psi for the RAV4).
  • If pressure is low, check the fuel filter and fuel pump for clogs or failure; replace as necessary.
  • Inspect fuel injectors for proper function; clean or replace if they are clogged or malfunctioning.

5. Perform Compression Test

• Sub-steps:
  • Remove spark plugs and insert a compression gauge into each cylinder.
  • Crank the engine and record the compression readings; compare against specifications (ideally 180-220 psi).
  • If readings are inconsistent, further internal engine diagnosis may be required.