1. Gather your tools and materials. You will need:
- A new set of spark plugs (check your owner's manual for the correct type and size)
- A spark plug wrench
- A ratchet and socket set
- A gapping tool
- A wire brush
2. Prepare your vehicle. Allow the engine to cool down completely before you begin working on it. Disconnect the negative terminal of the battery to prevent any accidental electrical shocks.
3. Remove the spark plug wires. Use your spark plug wrench to loosen and remove the spark plug wires from the spark plugs. Be careful not to drop the wires into the engine compartment.
4. Remove the old spark plugs. Use the spark plug wrench to loosen and remove the old spark plugs from the cylinder head. Be careful not to drop the spark plugs into the engine compartment.
5. Check the old spark plugs. Inspect the old spark plugs for signs of wear or damage. The electrodes should be clean and free of deposits. If the electrodes are worn or damaged, they should be replaced.
6. Gap the new spark plugs. Use the gapping tool to set the gap between the electrodes of the new spark plugs to the correct specification. The gap specification can be found in your owner's manual.
7. Install the new spark plugs. Hand-tighten the new spark plugs into the cylinder head until they are snug. Then, use the spark plug wrench to tighten the spark plugs to the specified torque. The torque specification can be found in your owner's manual.
8. Reattach the spark plug wires. Reattach the spark plug wires to the spark plugs. Make sure that the wires are securely attached.
9. Reconnect the negative terminal of the battery.
10. Start the engine and check for any problems. Start the engine and let it run for a few minutes. Listen for any unusual noises or check the engine for any warning lights. If everything seems normal, you have successfully changed the spark plugs in your 1991 Honda.
