Here's why:
* Spark plug gap varies based on the specific spark plug: The gap is determined by the manufacturer of the spark plug. You need to consult the manual for the specific spark plugs you are using.
* Ford recommends checking the gap: Your owner's manual will have the recommended gap based on the specific engine and spark plugs used.
Here's how to find the correct gap:
1. Consult your Owner's Manual: The manual will list the correct spark plug gap for your 1999 Grand Marquis.
2. Check the Spark Plug Packaging: The packaging of the spark plugs you purchase will also list the recommended gap.
3. Use a Spark Plug Gap Tool: These tools are readily available at auto parts stores and allow you to accurately measure and adjust the gap.
Important Note:
* Always use the proper spark plug gap. A gap that is too wide or too narrow can negatively affect engine performance and fuel economy.
* Before adjusting the gap, make sure the spark plug is clean and free of debris.
I hope this helps!
