2003 ford expedition 5.4 liter number 4 cylinder?

The "number 4 cylinder" in a 2003 Ford Expedition 5.4L refers to one of the eight cylinders in the engine. There's no special significance to cylinder #4 itself beyond it being one of the eight that contribute to the engine's operation. To understand what's going on, you need to provide more context. For example:

* What's the problem? Is cylinder #4 misfiring? Is it leaking oil? Is there low compression? Knowing the issue helps determine the cause and solution.

* What are the symptoms? Rough running engine, loss of power, check engine light, etc.

* What have you already checked? Have you checked spark plugs, wires, injectors, etc.?

Without more information, it's impossible to diagnose a problem with cylinder #4 in your 2003 Ford Expedition.