There's no single "1 piston position" for a 4.6L Ford engine. The position of a piston depends on the crankshaft angle, which changes constantly as the engine runs. To describe a piston's position, you need to specify the crankshaft's rotational position (e.g., Top Dead Center - TDC, Bottom Dead Center - BDC, or a specific crank angle degree).
A 4.6L Ford engine is a V8, meaning it has eight pistons. Each piston's position is independent of the others, though they're all connected to the crankshaft. Describing the position of *one* piston requires knowing which cylinder you're referring to (cylinder 1, 2, 3, etc.) and the crankshaft's rotational position.
