How to Find a Bad Coil on a 2006 F-150 5.4


The 2006 Ford F-150 was available with two versions of the 5.4-liter V-8 engine: a standard gasoline injected V-8 and a Flex Fuel V-8. The 5.4-liter V-8 produces 300 horsepower and 365 foot-pounds of torque. The engine is equipped with "Coil on Plug" technology, which uses a different ignition coil over each spark plug. The COP has three different modes: engine cranking, engine running and "CMP failure mode effects management," or FMEM. The coils can be tested individually without removing them from the engine.

Things You'll Need

  • Multimeter
  • 3/8-inch-drive ratchet
  • 3/8-inch-drive socket set
  • 3/8-inch-drive foot-pounds torque wrench (for replacement only)
  • New coil pack (optional)

Resistance Testing the Coil on Plug

  • Open the F-150 hood and disconnect the negative battery cable from the battery with a ratchet and socket.

  • Disconnect the ignition coil electrical connector from one of the coils. Turn the dial on the multimeter to the kilo-ohms setting in the ohms selection.

  • Install the two probes from the multimeter onto the two electrical connector posts on the coil pack. The resistance between the two posts should be between 5,000 and 6,000 ohms. If the ignition coil is not within these specifications, remove and replace the coil. If the measurement of this coil is within specification, connect the electrical connector, then repeat steps 2 and 3 to test the other seven coils. More than one coil pack could be failing, so test all eight coils.

Coil on Plug Replacement

  • Open the truck's hood and disconnect the negative battery cable with a ratchet and socket.

  • Disconnect the electrical connector from the faulty ignition coil. Remove the single mounting bolt from the top of the ignition coil, using a 3/8-inch-drive ratchet and socket.

  • Twist the coil from side to side while pulling the coil upward out of the engine.

  • Insert a small amount of dielectric grease onto the new ignition coil. Insert the coil into the engine and twist the coil while pushing it downward onto the spark plug. Install the single mounting bolt and tighten it to 53 inch-pounds with a 3/8-inch-drive torque wrench and socket.

  • Repeat steps 2 through 4 to replace any other bad coils on the truck. Install the negative battery cable onto the battery and tighten it snug with a ratchet and socket.

Tips & Warnings

  • Do not overtorque the bolts on the ignition coils if you are replacing any of your coils. The torque can crack the ignition coil and ruin it.

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  • Photo Credit Bill Pugliano/Getty Images News/Getty Images
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