The term “tune up” was originally derived from the practice of tuning an engine’s ignition timing. Modern automobiles use self-correcting, computer-controlled ignition, and so tuning is required very rarely. However, the term has survived to refer to a single service that covers multiple components, usually the following:
- Replacement of the fuel filter.
- Replacement of all spark plugs and wires. This may involve removing a manifold on certain engines, especially those with a V cylinder configuration.
- Replacement of various other ignition components, such as the distributor cap and rotor.
- Adjustment of the distributor cap angle on vehicles without electronic, or ‘distributorless’, secondary ignition usually with the aid of a timing light.
- Inspection of serpentine belts and replacement as needed.
- Replacement of the air filter.
- Adjustment of the clutch on cars equipped with a manual transmission.
- Battery service as needed, including cleaning any corrosion on the terminals.
- Replacement of the PCV valve.