How to Install an Ignition Coil on a 1999 F-250

The 1999 model year was an unusual one for the F-250, with Ford offering two very different versions of the truck. One version was the light-duty model, which had the same rounded body style as the F-150 and came with either a 4.6- or a 5.4-liter engine. The other model was the more rugged-looking Super Duty, which came standard with a 5.4-liter engine but also had a V-10 gasoline engine and a V-8 diesel engine available. Despite the engine size, replacing the ignition coil on any of the 1999 F-250 gas engines is a straightforward task.

Instructions

Ignition Coil Replacement on 5.4- or 6.8-Liter Engines

1

Open the F-250s hood and find the 8 or 10 ignition coil packs on the top of the engine, depending on whether the truck has a V-8 or V-10 engine. There are four or five coils on each side, just to the inside of the valve covers, depending on the number of cylinders.

2

Press and hold the unlocking button on the fuel injector wiring harness blocking access to the coil pack, on light-duty models only, and unplug the fuel injector wiring harness.

3

Unplug the wiring harness on the failed ignition coil by pressing and holding the unlocking button on the harness and pulling the harness from the coil pack.

4

Remove the bolt securing the coil pack to the engine, using a ratchet and socket. Pull up on the coil pack with a slight twisting motion to remove it from the spark plug.

5

Apply a small dab of dielectric grease meeting Ford specification ESE-M1C171-A to the inside of the rubber boot on the base of the ignition coil. Spread the grease around the inside of the boot with a small flat-head screwdriver.

6

Align the ignition coils rubber boot with the top of the spark plug and press the coil down until you feel it click onto the spark plug. Hand-thread the coil packs retaining bolt, then torque it to between 40 and 62 inch-pounds with an inch-pound torque wrench and socket.

7

Plug the wiring harness into the receptacle on the new ignition coil. On light-duty models only, plug the fuel injector wiring harness into the fuel injector.

8

Repeat steps 2 through 7 to replace any additional failed coil packs.

Ignition Coil Replacement on a 4.6-Liter Engine

9

Find the ignition coils on the front of each cylinder head, just below the valve cover.

10

Press and hold the unlocking button on the main wiring harness the larger harness plugged into the failed ignition coil and unplug the coil. Grab the radio capacitors wiring harness the smaller harness and pull it from the ignition coils radio capacitor.

11

Hold the new ignition coil next to the failed ignition coil so it is facing the same direction as the failed coil.

12

Squeeze and hold the locking tabs together on the top of one of the spark plug wires and pull the spark plug wire boot up off the ignition coil. Align the spark plug wire boot with the same post on the new coil that you pulled it off of on the failed coil. Press the boot onto the new ignition coils post until the locking tabs snap into place. Repeat this step until you transfer all of the spark plug wires to the new coil, then set the new coil on top of the valve cover.

13

Remove the four bolts securing the failed coil to its bracket, using a ratchet and socket, and remove the coil.

14

Set the new coil on the bracket and tighten its bolts to between 44 and 62 inch-pounds, using an inch-pound torque wrench and socket. Plug the radio capacitors wiring harness and the coils main wiring harness into their respective receptacles on the new coil.

15

Repeat steps 2 through 6 to replace the other coil, if needed.