How to Change the Spark Plugs on a Ford F150 4.6L Engine

Changing the spark plugs on your truck regularly is an important maintenance chore. Although spark plugs are durable and long-lasting, they need to be replaced when they go bad. It is important Ford F150 owners know the signs of a bad spark plug and how to change them, so they can keep their truck running smoothly and with the right level of power.

How Often Should Spark Plugs Be Changed?

The frequency of spark plug changes will depend on the vehicle and the amount of driving you do regularly. Ford F150s require changes about every 100,000 miles. Changing your plugs on schedule will help to ensure your Ford F150 does not experience power problems that could make its performance lag.

Signs Your Spark Plugs Need Attention

Unfortunately, a spark plug can go bad well before it is time to be changed. Some of the common reasons for premature failure include carbon buildup on the tip, overheating, and oil contamination. The following offers some signs that should alert F150 owners it is time to change their spark plugs.

  • Lack of acceleration
  • Hard starts
  • Reduction in gas mileage
  • Rough idle
  • Engine misfiring

If you have noticed any of these signs, it is time to pull the plugs and check each one for problems. If it has been close to 100,000 miles since your last change, pull them all and replace them.

How to Check a Spark Plug

Reading a spark plug is fairly easy, as long as you know what to look for. Consider the following information on how to read each spark plug for signs of fouls.

  • Dry black soot on the tip shows a plug has become carbon-fouled.
  • Black oily deposits on the tip mean an oil-fouled plug.
  • If the tip is wet, this can be a sign of engine flooding.
  • If the tip is burned, melted, or blistered, these are signs the plug is getting too hot.
  • When the electrodes become worn down, the plug is too old.
  • If the electrode is broken off, it is likely the wrong spark plug was installed.

If you have noticed a lack of performance with your Ford F150, it is a good idea to pull each plug and check the tips for the above signs. Now that you know what to look for, it is time to learn the steps involved in changing your spark plugs for a Ford F150 4.6L engine.

Plugs on a Ford F150 4.6L

How to Change Your Ford F150 Spark Plugs

The engineers over at Ford did not make changing spark plugs the easiest of tasks. They can be a little hard to reach. That being said, the job is not all that difficult with the right knowledge and tools. If this is your first time changing the plugs on your Ford F150, you may find it takes longer than you would have expected. After the first time, it is just like riding a bike, you never forget.

It is important to note that you will not be able to see each spark plug. You will have to remove them blindly, but if you know the correct positions, this will not be too difficult.

  • First, always remove the negative battery cable before removing any spark plugs. This protects you from accidental shocks.
  • Remove the plastic engine cover.
  • Unplug the fuel injector connectors and the ignition coil.
  • Remove the coil retaining bolt using a 7mm socket. Loosen it with the socket and then unthread it by hand the rest of the way, being careful not to lose the screw in the engine valley.
  • Pull the ignition coil upwards to remove it. This takes a rather firm tug. If the insulator boot separates from the coil, do not worry because this is normal.
  • Use compressed air to remove all dirt and debris from the bore. Failing to take this step could cause dirt and debris to enter the cylinder, and this is something you do not want.
  • Use a 5/8th inch or 9/16th inch spark plug socket with the correct extensions to remove the spark plug.
  • Verify the correct gap and then replace the old spark plug with the new one. Do not over-tighten. Repeat this until all spark plugs have been replaced.
  • Put the coils back in and bolt them. Then reconnect everything, with the last item being the battery cable.


Now, you know the steps involved in how to change the spark plugs on a Ford F150 4.6L engine. Although a couple of the plugs can be a bit tricky to get to, the process is not overly difficult.

With a little practice, you will find it to be a straightforward process. Besides following the steps above, it may be helpful to check out a few how-to videos for a visual.

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