1. Open the hood of the vehicle.
2. Locate the engine cover. It is usually held in place by several bolts or clips.
3. Remove the engine cover.
4. Locate the spark plug wires. They are connected to the spark plugs and are usually black or blue.
5. Follow the spark plug wires to the spark plugs. They are located at the top of the cylinder head, between the valve cover and the intake manifold.
6. To remove a spark plug, use a spark plug wrench to loosen the spark plug's nut.
7. Be careful not to drop the spark plug into the cylinder head.
8. Remove the spark plug and inspect it. If the spark plug is worn or damaged, replace it with a new one.
9. Install the new spark plug by hand, then tighten it with the spark plug wrench.
It is important to note that the spark plugs in a Ford Econoline E150 4.6 engine should be replaced every 100,000 miles or so. This will help to ensure that the engine is running properly and efficiently.
