The firing order for the 5.4L Triton V8 is 1-5-4-8-6-3-7-2.
Here's how to locate cylinder #1:
1. Passenger Side: The engine's number one cylinder is typically on the passenger side of the engine.
2. Front of the Engine: It's also usually towards the front of the engine block (closest to the radiator).
3. Firing Order: Now, use the firing order (1-5-4-8-6-3-7-2). Remember that the firing order describes the sequence in which the cylinders ignite. Therefore, Cylinder #1 will be the first cylinder to fire in the sequence.
4. Spark Plug Wires: The easiest way to confirm is by following the spark plug wires. The wire connected to the distributor cap (if equipped) or coil pack that corresponds to the #1 position in the firing order will lead you to cylinder #1's spark plug.
5. Visual Inspection (Trickiest): You might be able to visually identify the #1 cylinder by finding the front-most cylinder on the passenger side. *However, this is the least reliable method*. Always double-check using the spark plug wires.
Important Considerations:
* Distributor vs. Coil-on-Plug: The 1999 5.4L Triton might have a distributor or coil-on-plug ignition system. If it's coil-on-plug, the coil pack itself will be above the cylinder, making it easier to trace back to the cylinder.
* Engine Orientation: While typically positioned as described above, slight variations exist depending on the specific vehicle configuration.
* Consult a Repair Manual: The best way to be absolutely certain is to consult a repair manual specific to your 1999 Ford E-150 5.4L engine. The manual will have diagrams showing the engine layout and clearly indicate the location of cylinder #1.
In summary, while you can make an educated guess based on typical engine layout, using the firing order and tracing the spark plug wire is the most accurate and reliable method to locate cylinder #1. A repair manual is your best resource to eliminate any doubt.
