1. Check your owner's manual. The owner's manual for your vehicle will likely include a diagram showing the location of the spark plugs in the engine.
2. Search online. There are many websites that provide diagrams for spark plugs, including the following:
* [NGK Spark Plugs](https://www.ngksparkplugs.com/en/resources/spark-plug-finder)
* [AutoZone](https://www.autozone.com/repairguides/Ford-F-Series-150-1997-03/Engine/Spark-Plugs/Testing-and-Replacing/_/P-0996b43f80f1d2d3)
* [Advance Auto Parts](https://www.advanceautoparts.com/parts/ford/f-150/ignition-system)
3. Visit your local auto parts store. Most auto parts stores will have a diagram of the spark plug locations for your vehicle.
Here are some tips for finding the spark plug diagram for your 2004 F-150 4.6 engine:
* Make sure you have the correct year, make, and model of vehicle.
* If you are searching online, use the search terms "spark plug diagram," "spark plug locations," or "ignition system diagram."
* If you are visiting an auto parts store, ask a knowledgeable salesperson for help.
Once you have found the spark plug diagram for your vehicle, you can use it to identify the location of the spark plugs and properly replace them.
