Electronic ignition, computerized engine controls, and electronic fuel injection have eliminated many adjustments that were once part of a “traditional” tune-up. Most would agree that a tune-up today is a preventive maintenance service and engine performance check.
Call it what you will, a complete tune-up should combine elements of preventive maintenance, adjustment and performance analysis. One of the main reasons people bring a vehicle in for a tune-up is because they are experiencing some kind of driveability problem.
Things like hard starting, stalling, hesitation, misfiring, poor fuel economy, or lack of power are seldom cured by a new set of spark plugs and a few turns of a screwdriver. Every tune-up should include a comprehensive performance check to verify that no driveability problems or trouble codes exist.
Taking into account longer service intervals and reduced maintenance requirements of today’s vehicles, a tune-up is probably only necessary every 30,000 miles, or once every two to three years. This is altered when a driveability or emissions problem arises that requires diagnosis and repair.
The best guide to tune-up frequency is probably the recommended spark plug replacement interval in a vehicle’s owners manual.
Our list of items that should be included in a “complete” tune-up include:
Replace spark plugs
Check distributor cap (replace if necessary)
Check timing (adjust if necessary)
Check ignition wires (replace if necessary)
Check ignition performance (firing voltage and ignition patterns)
Check idle speed (adjust if necessary)
Check choke (carbureted engines)
Clean fuel injectors
Check compression and/or power balance (identifies bad fuel injectors as well as compression problems)