What should a complete tune-up include?
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.
Another item that should be included is an emissions check.
Thirty-five states now have some type of annual vehicle emissions
inspection program, and all but two include a tailpipe emissions
check. Most mechanics will check EGR valve operation, the PCV valve,
and make a visual inspection of other emission control components
and plumbing. But unless an actual emissions performance check is
made at the tailpipe, there is no way to know whether or not the
vehicle will meet applicable emission standards. An emissions check
is a must.
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
> Replace rotor
> 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)
> Check manifold intake vacuum (reveals exhaust restrictions)
> Check battery/charging voltage
> Check exhaust emissions (verifies fuel mixture, ignition
performance and emissions performance)
> Check vehicle computer for trouble codes
> Install new air filter
> Replace fuel filter
> Replace PCV valve
> Check all emission controls (EGR valve, air pump, etc.)
> Check all vital fluid levels (engine oil, transmission fluid,
coolant, brakes, power steering)
> Check belts and hoses
> Check safety items such as lights, wipers, tires (including
inflation pressure), horn, etc.
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