Time: 30min-1hr

Difficulty - Moderate

Cost - $60-150 (plug type, boots)

WHY

Good spark plugs help ensure an efficient fuel burn which contributes to fuel economy and performance. Worn-out spark plugs increase electrical resistance and strain on ignition components such as the coils and ignition boots. They also cause poor combustion, wasting fuel and reducing horsepower. 

WHEN

The interval for replacing platinum or iridium spark plugs can range from 60,000-150,000 miles depending on driving conditions and vehicle health.  Planning to replace spark plugs around 100,000 miles is a nice round number that falls in the middle of that range.

METHOD

Spark plugs are replaced by removing the ignition coil and then the plug from the top of the cylinder head. A magnetic socket (or socket with a rubber boot) can make removal and installation easier. The new spark plug is then properly gapped and reinstalled to the specified torque.

Platinum and Iridium plugs typically come pre-gapped for optimal spark, but it's a good idea to check the gap with a feeler gauge in case there are any outliers from shipping.

Watch the video below to see how the spark plugs were replaced on a 2015-2024 era Ford F150 with the 3.5L EcoBoost.