Tools and materials needed:
- Socket wrench set
- Spark plug wrench
- Gapping tool
- New spark plugs (NGK or Denso are recommended)
Difficulty: Easy
Time required: Approximately 30 minutes
Step 1: Preparing
- Turn off the engine and let it cool down.
- Open the hood of the car.
- Disconnect the negative terminal of the battery to ensure there's no electrical current.
Step 2: Removing the Ignition Coils
- Locate the ignition coils on top of the engine. There are four coils, each connected to a spark plug.
- Disconnect the electrical connectors from each ignition coil by pressing down on the tabs and pulling straight up.
- Remove the 10 mm bolts holding down each coil using the socket wrench.
- Carefully lift off the ignition coils, being careful not to drop them.
Step 3: Removing the Spark Plugs
- Using the spark plug wrench, turn counterclockwise to loosen and remove the old spark plugs.
- Be careful not to drop the spark plugs into the engine.
Step 4: Checking the Spark Plugs
- Inspect the old spark plugs for signs of wear, such as erosion, fouling, or deposits.
- Compare the old spark plugs with the new ones to ensure they are the same size and type.
Step 5: Adjusting the Spark Plugs
- Check the gap between the center electrode and the ground electrode on the new spark plugs.
- Use the gapping tool to adjust if needed. The recommended spark plug gap for the 1999 Honda Civic is 0.039 to 0.043 inches (1.0 to 1.1 mm).
Step 6: Installing New Spark Plugs
- Hand-tighten the new spark plugs into their respective holes until snug.
- Do not over-tighten the spark plugs, as this can damage the threads.
- Use the spark plug wrench to tighten the spark plugs a quarter to half turn past finger tight.
Step 7: Re-Installing the Ignition Coils
- Place the ignition coils back into their respective positions.
- Secure them with the 10 mm bolts you removed earlier.
- Reconnect the electrical connectors to each coil.
Step 8: Reconnecting the Battery
- Reconnect the negative terminal of the battery.
Step 9: Testing
- Start the engine and let it run for a few minutes.
- Listen for any unusual noises or check the engine light to ensure it's not illuminated.
Step 10: Final Check
- Double-check all connections to ensure they are secure.
That's it! You have successfully replaced the spark plugs on your 1999 Honda Civic. Remember, spark plug replacement intervals can vary depending on the vehicle and driving conditions. Refer to your owner's manual for the recommended replacement schedule.
