EXPRESS

The nature of an engine tune–up has changed considerably over the years, but the basics of how a gasoline engine works has not. Clean gas and air needs to be driven to the vehicle’s cylinders, where combustion initiated by a spark plug creates the power necessary to move a heavy vehicle. Clogged fuel injectors, dirty air and fuel filters, and corroded spark plugs can all decrease engine performance and contribute to decreased gas mileage and performance.