The meat and potatos of a tune-up service are the spark plugs. Your engine breathes in a mixture of air and fuel. This mixture needs to be ignited and your spark plugs are the missing ingredient. If your spark plugs and ignition system aren't running at optimum levels, you can expect an unhappy motor.
Just as allergies can prohibit proper airflow through your nasal passages, dirty air filters block air flow through your engine. Air filter replacement is essential with every tune up. Most air filters are replaceable; some you can clean and re-install. Nevertheless, a clean filter means a cleaner running engine.
The third essential component of a tune-up is the fuel system. Your fuel system also has a filter (not applicable to all). Just as air filters clog, fuel filters get clogged too. This can lead to starting issues, rough idles, misfires and the list goes on. Needless to say, your engine will have a bad day.
*Note: Spark plugs replacement varies by manufacturer. 70,000 to 100,000 miles has been the standard. Always replace your spark plugs with the same ones that came with the vehicle.
Removal & replacement of old spark plugs with new, OEM rated spark plugs
Visual inspection of old plugs for signs of contaminants (oil, fuel etc.)
Multi-point inspection of engine components
Top off brake fluid (if necessary)