how to resolve a P0301 misfire code in my Toyota Corolla E140 (2006-2013)?

Solution

1. Preparation

• Gather tools and materials.
• Disconnect the battery negative terminal to prevent electrical shocks.
• Tools Required: Socket set, torque wrench, multimeter, OBD-II scanner, compression tester.

2. Inspect and Replace Ignition Components

• Sub-step 1: Remove the ignition coil from cylinder 1 by unbolting it and disconnecting the electrical connector.
• Sub-step 2: Remove the spark plug from cylinder 1 using a spark plug socket.
• Sub-step 3: Inspect the spark plug for wear or fouling; replace with a new spark plug if necessary (specification: gap should be set to 0.043 inches).
• Sub-step 4: Test the ignition coil with a multimeter (should typically show 0.5-2.0 ohms primary resistance). Replace if faulty.
• Sub-step 5: Reinstall the spark plug and ignition coil, ensuring proper torque (spark plug: 13 lb-ft; ignition coil: 7 lb-ft).

3. Check and Clean Fuel Injector

• Sub-step 1: Disconnect the fuel injector connector for cylinder 1.
• Sub-step 2: Use a multimeter to test the injector for continuity (should show around 12-16 ohms).
• Sub-step 3: If the injector is faulty, replace it. If it is operational, clean the injector using a professional fuel injector cleaning kit.
• Sub-step 4: Reconnect the fuel injector connector.

4. Compression Test

• Sub-step 1: Remove the spark plug from cylinder 1.
• Sub-step 2: Insert the compression tester into the spark plug hole.
• Sub-step 3: Crank the engine for about 5 seconds and record the compression reading (should be within manufacturer specs, typically around 180-200 psi).
• Sub-step 4: If compression is low, further investigation is required for potential internal engine damage.

5. Inspect for Vacuum Leaks

• Sub-step 1: Visually inspect all hoses and connections around the intake manifold for cracks or disconnections.
• Sub-step 2: Use an aerosol spray (like brake cleaner) around suspected areas while the engine is running; if RPM changes, there’s a leak.
• Sub-step 3: Replace any damaged hoses or gaskets found during inspection.