Tune-Up Checks

Tune-ups should start with performance checks to base line checks or confirm the engine’s overall condition. These should include:

• Load Test Battery – Important with all of today’s on board electronics to know your charging voltage.
• Scan for Fault Codes- To verify no fault codes are present, or to retrieve any codes that may be present so they can be diagnosed and eliminated
• Check Ignition Timing – To detect possible computer or sensor problems for the operation of the EGR valve.
• Hoses and Belts- Belts and Hoses can dry out and crack over time so it is good to have them checked to see how they are wearing and to make sure everything is in good condition.
• All fluids- Oil, Coolant, Automatic Transmission Fluid, Power Steering Fluid and Brake Fluid, should also be inspected to make sure all are at the proper level, and that the appearance and condition of each is acceptable.

What to Replace

If the tune-up checks find no major faults, the following items should be replaced for preventive maintenance:

• Spark plugs
• Rotor and Distributor Cap (if required)
• Fuel filter, Air filter, PCV Valve and Breather Filter
• Oxygen (O2) Sensor(s).

Spark plugs need to be changed periodically to help keep your engine running at its maximum performance.

Oxygen Sensor

Sluggish O2 sensors cause a lot of drive-ability problems. To prevent such woes, the O2 sensor can be replaced for preventive maintenance during a tune-up.

The O2 sensor is the master switch in the fuel control feedback loop. The sensor monitors the amount of unburned oxygen in the exhaust and produces a voltage signal that varies from lean to rich. The computer uses the O2 sensor’s signal to constantly fine tune and flip-flop the fuel mixture so the catalytic converter can do its job and clean the exhaust. If the O2 sensor circuit opens, shorts or goes out of range, it usually sets a fault code and illuminates the Check Engine or Malfunction Indicator Lamp. An O2 sensor that is badly degraded will continue to function well enough not to set a fault code but not well enough to prevent an increase in emissions and fuel consumption.

A sluggish sensor may not allow the computer to flip-flop the fuel mixture fast enough to keep emissions within acceptable limits. A dead sensor will causes the system to go back into open loop with a fixed, rich fuel mixture. Fuel consumption and emissions go up, and the converter may suffer damage if it overheats.