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Tune Up: What Exactly Is It?

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What is a Tune Up?

The phrase "My car needs a Tune Up" is probably the most spoken phrase by car owners on a day by day basis in the Automotive Service and Repair Industry other than "Oil and Filter Change".  When a Service Writer or Technician asks the driver why the vehicle needs a "Tune Up", the customer will usually say that the vehicle does not run properly in some way.

It could be idling rough, it could be hard to start, it could lack power, it could be getting poor mileage or have many other possible symptoms.  Many people believe that a "Tune Up" will solve all or most of these problems, but modern cars do not require "Tune Ups" and poor performance almost always means the car needs a repair.

The phrase "Tune Up" is from a time when automobiles were not computer controlled and an Auto Mechanic could actually adjust the Timing, Idle Speed, Fuel Mixture and other things to "Tune Up" the operation of the Engine, very much the way a Piano Tuner will "Tune Up" a Piano to bring it back into proper pitch and operation by adjusting the tension on the strings, adjusting the action and reshaping the hammers.

Maintenance: The Modern Day Tune Up

Presently the term "Tune Up" actually refers to replacing and servicing the wear items in the Ignition System and Fuel System.

• The Air Filter and Fuel Filter will become less efficient and need replacing.
• The Spark Plug electrodes will wear down and need replacing.
• There will need to be some cleaning or decarbonizing of the Throttle Body and Fuel System from the Oil Vapors produced by the Positive Crankcase Ventilation (PCV) System.

There are no adjustments needed (or possible) for the most part, because the Engine Computer Controls all the functions of the Ignition and Fuel System. The "Tune Up" is often part of a large 30,000/60,000/90,000 mile service that includes inspections, fluid and filter changes, and these services are part of the manufacturer's recommended scheduled maintenance detailed in the vehicles owner's manual.

The present day vehicle should not exhibit any performance problems by the time a "Tune Up" is due. If there are any performance problems, usually a Check Engine light will illuminate, indicating that the vehicle needs some attention because it is not running properly and is now polluting the Air.

Tune Ups: Some Historical Perspective

Up until the middle 1970's most gasoline powered cars and light trucks had Spark Plugs, Spark Plug Wires, a single Ignition Coil, a Distributor Cap and Rotor, a set of Ignition Points and a Condenser.  A Carburetor would combine the fuel with air and then deliver this "Mixture" to the Cylinders.  All of these components needed regular adjustments, or a "Tune Up".

Compared to the vehicles of the 21st century, these technologies were very crude and required a lot of care (many "Tune Ups") to properly maintain them. The Spark Timing would go out after 10,000 miles of driving because the Ignition Points would wear and become pitted or "burnt". The Spark Plugs would foul and not work properly because the Carburetor would get dirty and varnished from all of the Oil Vapors being recycled into the Air Cleaner from the Positive Crankcase Ventilation (PCV) System. This varnish would plug up the Air Bleeds in the Carburetor and prevent it from mixing the Fuel properly with the Air. The Spark Plug Wires were usually damaged from Oil leaking on them from the older style cork and rubber Valve Cover Gaskets. It was common for a vehicle to need a "Tune Up" every year, or even more often if the vehicle was driven more than 10,000 miles per year, as the Engine would be running because of any or all of the above problems.

By the middle 1980s, most vehicles had 1-2 computers involved with the management of the Engine Operation because the Environmental Protection Agency found that when cars needed to be "Tuned Up," the amount of tail pipe emissions would increase exponentially.

The Ignition System was the first to receive Electronic and later Computer Controls. The Ignition Points and Condenser were replaced by a Transistor Controlled Ignition Module that could last the life of the vehicle. Once the Ignition Timing was set, it could stay properly adjusted for 30,000 or more. Valve Covers and Valve Cover Gaskets started using Air Craft Engine designs and would not leak for over 90,000 miles. This meant that the Spark Plug Wires could last upwards of 60,000 miles before they failed electrically.

By the middle 1980s Electronic Port Fuel Injection was phasing out the Carburetor. The ratio of the Air Fuel Mixture was now Computer Controlled. This allowed for precise compensation to reflect the ever changing demands put on an Engine due to ever changing driving and weather conditions. Fuel Injection is not nearly as vulnerable to the PCV Oil Vapors because there are individual Injectors for each Cylinder located away from the flow of the Positive Crankcase Ventilation Oil Vapors.

By the late 1990s, most vehicles were using individual Coils for each Cylinder and the Spark Plugs had Platinum tipped Electrodes. This eliminated Distributor Caps and Rotors and most Ignition Wires. The Platinum tipped Spark Plugs meant that the Plugs could easily go for 60,000 miles, as opposed to the usual 30,000.  Some Manufacturers were advertising that the car could go 100,000 miles with out a "Tune Up", however many found that the Spark Plugs rusted into the Cylinder heads. This meant that a major repair was required to remove them that could easily cost hundreds if not thousands of dollars. 60,000 miles has proven to be a much more realistic and reliable mileage interval and many manufacturers are switching back to this recommendation.

Daniel Dillon has 22 years of experience as a licensed Smog Technician in California. He helped write test questions for the California Smog Technician Exam, and has performed Consumer Assistance Program and gold shield diagnostic work for the state. He also was an instructor for SnapOn Tool Corporation.