Where is the number eight plug located on 5.4 ford engine 1999 expidition?

There's no "number eight plug" on a 1999 Ford Expedition 5.4L engine in the same way you might number spark plugs in a straight-line engine. The 5.4L Triton V8 has two banks of cylinders (V-shaped) and uses a firing order. Each cylinder has its own spark plug, and they're numbered according to the firing order, not a simple left-to-right, front-to-back numbering scheme.

To find the location of a specific spark plug, you'll need either:

* A Workshop Manual: This is the best resource. It will show a diagram of the engine with the spark plug locations clearly labeled according to the firing order.

* A Repair Manual specific to your year and engine: Same as above, crucial for accuracy.

* An Online Diagram: Search for "1999 Ford Expedition 5.4L spark plug location diagram." Be cautious of the source's reliability; a reputable site like a parts store's website is ideal.

Without a diagram, attempting to locate a specific spark plug by number alone is highly discouraged. Misidentifying a spark plug could lead to engine damage. Always use a reliable resource to properly identify the location of each spark plug.