The 2003 Ford E250 cargo van came with a few different V6 engine options. To know the firing order definitively, you
need to know the exact engine code. This is usually found on a sticker on the engine itself or in your owner's manual.
Once you have the engine code, you can look up the firing order in a repair manual specific to that engine. Without that code, it's impossible to give you the correct firing order.
