One of the leading causes for a rough running engine, and poor fuel mileage is lack of a tune up service. Tune up components are truly what keeps your vehicle running at optimum performance. These items normally consist of the following; Spark Plugs, Ignition Wires, Distributor Cap, Distributor Rotor, PCV Valve, Air Filter, Fuel Filter. All of these items are “wear” items, meaning over time they cause normal wear on themselves. Spark plugs slowly burn themselves out of manufacturer recommended specifications, or “Gap”. Ignition wires become brittle over age due to high engine temperatures, which can cause the outer protective sleeve to crack/chip. This results in the wires begin able to arc/ground out on metal areas of your engine compartment, causing misfires. Your distributor cap/rotor deliver ignition spark to your wires/plugs. Over time the metal contact points that deliver the spark start to wear down, and become corroded due to moisture. This results in a weak spark which stresses other parts of the electronic ignition system to work harder than normal. The Positive Crankcase Ventilation Valve is a one way valve that ensures proper continual evacuation of gasses, from inside a gasoline internal combustion engine’s crankcase. This valve can become clogged with debris that causes it to start blocking these gasses from properly exiting the engine. Air filters allow air to pass through them, while filtering the air, not allowing harm causing debris to pass through to the engines internals. Your air filter can become clogged with dirt/debris that it filters from the air going into your motor. As air filters start to clog up they restrict the amount of air allowed into your engine, resulting in poor fuel mileage, and sometimes rough running conditions. Fuel filters basically work the same way as an air filter. As fuel from your tank passes through a fuel filter it removes any unwanted debris that may have come from the gas you put in, or sediment in your tank. Over time the filtered debris starts to clog up the filter which will eventually cause a restriction in the fuel system. Once this happens your fuel pump starts to overwork itself trying to provide proper amounts of fuel to the engine, and it can result in poor running conditions. As you can see all of these components have a very important role in keeping your vehicle running at optimum performance. Staying on top of this service will ensure your vehicle stays running well, along with providing you with good fuel mileage.