Long ago, in the before times there was once an ancient machine of terrible inefficiency called the carburetor. This machine was the mechanism by which cylinders got their fuel. Carburetors periodically needed to be adjusted or “tuned” this is where we get the phrase “tune up”. Since the late 80’s cars have employed fuel injectors which spray a specifically calculated amount of fuel into the cylinder. Therefore there is no longer any tuning involved in a tune up, instead it consists of changing spark plugs and air filters. This is not to say that “tune ups” are not important, it is in fact very important that spark plugs be changed at the interval specified by the manufacturer in order to avoid a misfire which can cause damage to other parts of the car.