Tuneups

Tuneups are a maintenance service intended to restore or maintain the performance and efficiency of internal combustion engines and related systems. Historically, tune-ups targeted ignition and fuel delivery components to ensure reliable starting and smooth running. In older gasoline engines with carburetors and ignition points, a tune-up typically included inspecting and replacing spark plugs and ignition points, adjusting distributor timing, cleaning or calibrating the carburetor, inspecting the vacuum and idle circuits, and replacing filters.

In modern vehicles, most engines are fuel-injected and controlled by an onboard computer. As a result, a traditional tune-up is less common, and maintenance focuses on fault diagnosis, routine replacements, and software-based adjustments. Common tasks today may include checking or replacing spark plugs (per the manufacturer’s interval), inspecting ignition coils and wires, inspecting air and fuel filters, checking fluids and belts, scanning for diagnostic trouble codes, inspecting the PCV valve and vacuum leaks, and performing an idle and emissions-related inspection. Some services marketed as tune-ups may also include fuel-system cleaners or injector service, though the value of these treatments varies by vehicle.

Frequency and scope depend on the vehicle and manufacturer recommendations. Signs that a tune-up or service may be needed include reduced fuel economy, rough idle, misfires, hesitations, starting difficulties, or increased emissions.

A tune-up is a form of preventive maintenance aimed at sustaining engine efficiency, performance, and emissions compliance, and it is distinct from major repairs. The term is also used in other domains, such as tuning musical instruments, but this article concentrates on automotive tuneups.