how to diagnose a misfire on Toyota Corolla E170 (2013-2019)

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative terminal of the battery to ensure safety while working on the electrical components.

2. Inspect and Replace Spark Plugs

• Tools Required: Socket set, torque wrench, spark plug socket.
• Remove the ignition coils by unscrewing them from the cylinder head.
• Carefully pull out the old spark plugs using the spark plug socket.
• Inspect the old spark plugs for signs of fouling or wear. Replace with new spark plugs if necessary.
• Install the new spark plugs and torque them to the manufacturer’s specifications (typically around 13-15 lb-ft).
• Reinstall the ignition coils ensuring they are seated properly.

3. Inspect and Replace Ignition Coils (if needed)

• Tools Required: Socket set, torque wrench.
• If any ignition coils were found to be faulty during inspection, remove the screws holding the coil in place.
• Disconnect the electrical connector from the ignition coil.
• Install the new ignition coil and reconnect the electrical connector.
• Torque the mounting screws to manufacturer specifications (typically around 7-9 lb-ft).

4. Check Fuel System

• Tools Required: Fuel pressure gauge.
• Connect the fuel pressure gauge to the fuel rail.
• Turn on the ignition to prime the fuel system; check the fuel pressure reading against the manufacturer specifications (typically around 40-50 psi).
• If the pressure is low, inspect the fuel pump and filter for issues and replace if necessary.

5. Inspect for Vacuum Leaks

• Tools Required: Smoke machine (optional) or carburetor cleaner.
• Use a smoke machine to detect vacuum leaks around the intake manifold and hoses.
• Alternatively, spray carburetor cleaner around the intake area while the engine is running; if the RPM increases, this indicates a leak.
• Replace any damaged or cracked hoses.

6. Perform Compression Test

• Tools Required: Compression gauge.
• Remove the spark plugs to allow for easier cranking of the engine.
• Insert the compression gauge into the spark plug hole and crank the engine.
• Compare the compression readings with manufacturer specifications (typically around 180-200 psi).
• If readings are low, further diagnosis of the internal engine components may be necessary.