The term “tuneup” is open to interpretation and varies between each car. Before the use of electronic ignition and computers, tuneups included replacing the spark plugs and wires, filters, adjusting the timing, and setting the points. Though it lacks the adjustable points and timing, your 2003 Mustang GT does have a list of maintenance items that most experts consider part of a modern tuneup.
Recommended Tune Up Schedule
In Normal driving conditions, Ford recommends changing the spark plugs — what most experts consider the main component of a modern “tuneup” — every 100,000 miles. The interval goes to every 60,000 miles with excessive slow driving or idling. Another common part of a tuneup is replacing the air filter, which Ford recommends doing on your Mustang every 30,000 miles under normal conditions. In dusty conditions, the recommended mileage interval drops to every 15,000 miles. The last common process during a tune is to replace the fuel filter, which Ford recommends doing every 30,000 miles on your 2003 Mustang.