how to diagnose a misfire in my Honda Accord 8th Generation (2008-2012) with code P0301?

Solution

1. Preparation

• Tools Required: OBD-II scanner, socket set, torque wrench, multimeter, compression tester, fuel injector cleaning kit.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the engine to cool before working on components.

2. Replace Spark Plug

• Remove the ignition coil from cylinder 1 using a socket set.
• Remove the spark plug using a spark plug socket, inspect for wear or damage.
• Install a new spark plug, ensuring it is gapped to manufacturer specifications (typically 0.043 inches for Honda).
• Reinstall the ignition coil and torque to specification (usually 7.2 ft-lbs).

3. Test/Replace Ignition Coil

• Disconnect the electrical connector from the ignition coil.
• Use a multimeter to test the primary and secondary resistance; refer to manufacturer specifications.
• If the coil is defective, replace it with a new one and reconnect the electrical connector.

4. Perform Compression Test

• Remove the spark plug from cylinder 1.
• Insert the compression tester into the spark plug hole.
• Crank the engine to take a reading; compare the result to manufacturer specifications (typically around 190 psi).
• If compression is low, investigate further for potential causes such as valve issues or head gasket leaks.

5. Inspect Fuel Injector

• Disconnect the fuel injector connector and use a multimeter to check the injector resistance (should be around 12-16 ohms).
• If the injector is faulty, replace it. Consider cleaning it using a fuel injector cleaning kit if it appears clogged.