Let me Google a good definition!  

Assistant:  Here’s a good definition: "Tune-ups, called service items by the industry, consist of a range of maintenance activities, such as oil changes, replacement of worn or faulty parts, and replacement of air filters and spark plugs."
assitant
It’s when you adjust the carburetor (a fancy way of saying the engine’s intake system).
assistant
What is some easy car maintenance I can do myself to save money?
user
Gosh, I’d say a tune up and an oil change should do the trick!  Do you know what a “tune up” is?
assistant
No, what is a tune up?
user