The spark plugs on a 2003 Ford 5.4L Triton V8 engine are located on
the top of the engine, between the valve covers. However, accessing them requires removing several components, including the upper intake manifold. This is
not a simple job and usually requires some mechanical skill and the right tools. It's not something you can just quickly reach in and change.
Because of the difficulty, consulting a repair manual specific to your 2003 Ford 5.4L engine is highly recommended. A manual will show you exactly where each plug is located and detail the removal and installation procedure. Pictures and diagrams will be invaluable.
