Tune-Up Basics - Boost Your Spark

Getting Started

Fouled, damaged, or worn out spark plugs can lead to a variety of engine problems, such as misfires, hard starts, increased emissions, and poor fuel economy. For most vehicles, you should replace your spark plugs every 30,000 miles (consult your owner's manual for your specific interval). It is also recommended that you replace your spark plug wires at the same time, or you may still experience misfires or other problems. Follow these 11 steps to give your vehicle a simple ignition tune-up.


Allow your engine to cool for 3 to 4 hours before changing your spark plugs. They can be extremely hot if you do not allow enough cooling time.


If you plan to keep your original wireset, take the time to label each spark plug wire with masking tape and a marker.

  •  Putting your spark plug wires back in the wrong order can cause your engine to run rough.

Remove each spark plug wire by pulling the boots to avoid breaking the wires.


Check your vehicle repair guide to determine the necessary socket size and the correct gap for your spark plugs.


Use a spark plug gapping gauge to achieve the specified gap on your new plugs.


Be sure to use a spark plug socket with an internal gasket. This will grip the spark plug so you won't drop it during removal or installation.


Examine your spark plugs after you remove them for signs of mechanical problems.

  •  Be careful not to allow dirt or other foreign materials to fall into the cylinder head when your spark plugs are removed.

If your engine has aluminum cylinder head(s), you should use an anti-seize lubricant on the spark plug threads to prevent a negative reaction between the two different metals.


Use a torque wrench to install your new spark plugs and tighten to the specifications given in your vehicle repair guide.


 If you are replacing your spark plug wires, consult your vehicle repair guide for a wiring diagram. You must be sure to connect each wire in the proper sequence on both the distributor cap and the cylinder head.


 Use a dielectric grease on the inside of each spark plug wire boot to ease removal in the future. Connect the spark plug wire boots to complete the job.