Here's a general guide. Remember, this is a simplified overview; variations may exist depending on specific engine modifications.
Tools You'll Need:
* Socket wrench set: A 5/8" socket is typically used for the spark plug, but double-check your owner's manual. You'll also need extensions to reach the plugs.
* Spark plug socket: A deep well spark plug socket is crucial to avoid damaging the spark plug insulator. This socket will likely be 5/8" as well.
* Ratchet: To turn the socket.
* Wrench: To loosen the coil packs (if applicable). The size will vary depending on your engine; consult your manual.
* Needle-nose pliers or a small pick: To help remove any debris from the spark plug wells.
* New spark plugs: Purchase the correct type and gap for your Mustang's engine. Your owner's manual will specify this.
* Gloves: To protect your hands.
* Shop towels or rags: To clean up any spills or debris.
* Torque wrench (highly recommended): To tighten the spark plugs to the correct specification. Over-tightening can damage the threads, and under-tightening can lead to misfires.
Procedure:
1. Safety First: Disconnect the negative (-) terminal of your battery. This prevents accidental shorts or shocks.
2. Locate Spark Plugs: The spark plugs are located on top of the engine. You'll need to remove the top engine cover (if present) to access them.
3. Remove Coil Packs (if applicable): Your 1999 Mustang V6 may have individual coil packs over each spark plug. If so, you'll need to:
* Disconnect the electrical connector: Carefully unplug the electrical connector from the top of each coil pack.
* Remove the coil pack: Use the appropriate wrench to unscrew the coil pack and carefully remove it. Set it aside, being careful not to damage the connectors.
4. Remove Spark Plugs:
* Clean the area around the spark plug well: Use compressed air or a brush to remove any dirt or debris.
* Use the spark plug socket: Carefully insert the spark plug socket onto the spark plug. Ensure it's seated correctly before turning.
* Loosen the spark plug: Turn the spark plug counter-clockwise using the ratchet. It may be tight, so apply firm but controlled pressure.
* Remove the spark plug: Once loosened, carefully remove the spark plug by hand.
5. Install New Spark Plugs:
* Check the gap: Before installing the new plugs, make sure the gap is correct. Use a spark plug gap tool if necessary.
* Install the new spark plug: Hand-thread the new spark plug into the well. Do not force it.
* Tighten the spark plug: Use the spark plug socket and ratchet to tighten the plug to the manufacturer's specified torque. Crucially, use a torque wrench to avoid damage. Over-tightening is a common mistake.
6. Replace Coil Packs (if applicable): Reinstall the coil packs and reconnect the electrical connectors.
7. Reconnect the Battery: Reconnect the negative (-) terminal of the battery.
8. Start the Engine: Start the engine and listen for any unusual sounds or misfires.
Important Considerations:
* Torque Specifications: This is extremely important. Find the correct torque specification for your spark plugs in your owner's manual. Over-tightening can strip the threads in the cylinder head, requiring costly repairs.
* Cleanliness: Keep the area clean to avoid dropping debris into the cylinder wells.
* Damaged Spark Plugs: If a spark plug breaks off in the cylinder head, you'll need professional help.
This guide provides a general overview. Always consult your owner's manual for specific instructions and torque specifications for your 1999 Ford Mustang V6. If you're not comfortable performing this task yourself, it's best to take your car to a qualified mechanic.
