Spark plugs, wires, distributor caps and rotors break down and fail over time due to exposure to moisture, oil, grease and under hood temperatures that can reach as much as 550 to 700 degrees. Worn spark plugs require higher voltage, forcing the ignition module and coil to produce increasingly higher and higher voltages to overcome the resistance. This breaks down the spark plug wire's insulation causing the ignition module and coil to produce even more voltage, creating even higher temperatures within them. The increased resistance weakens transistors and electrical insulation within modules, coils and computers, resulting in intermittent and premature failure. For maximum fuel economy and peak engine performance, your spark plugs should be replaced every 30 months or 30,000 miles, unless your vehicle is equipped with 100,000-mile platinum tipped spark plugs. Vehicles 15+ years old are more likely to have standard plugs with approximate life expectancy of 12,0 ... read more

Today's automobiles do not require tune ups in the same way as older vehicles. Automobile manufacturers have set forth, in their recommended maintenance schedules, intervals for replacing spark plugs, PCV valves, fuel filters etc., while recommending that other items related to engine operation be inspected for proper operation and/or adjustment, such as ignition timing, idle speed and other emission control related devices. Therefore, the term "tune up" indicates the need for routine maintenance and should not be associated with poor performance. If your vehicle experiences any operation or performance problems between maintenance intervals, that specific problem should be addressed by performing an engine analysis to isolate that particular problem