On The Road

Today's cars have tuned out the tune-up

I frequently get asked, “When’s my next tune-up?” I then have to ask the customer what kind of car they have, what year it is and how many miles. I need to know this because most modern cars do not require tune-ups.

To better understand this, let’s first define what a tune-up is: It basically means to make an adjustment. Because all modern cars are computer controlled, the tune-up is pretty much dead.

It has been approximately 20 years now since we have performed the old-school tune-up. There used to be several parts on a car that could be adjusted. You could gap spark plugs, adjust points, adjust timing, adjust the fuel mixture, adjust valves and adjust the idle. The classic minor tune-up was spark plugs, point, adjust timing, air filter and oil change. The major tune-up included spark plugs, points, timing adjustment, idle adjustment, oil change, fuel filter, air filter and valve adjustment. The minor tune-up was performed every 3,000-6,000 miles, and the major tune-up every 15,000-20,000 miles, depending on the car.

Tune-ups lose their spark

The reason the term “tune-up” is really not pertinent anymore is because all of the above components or systems have evolved over the years. The early-style resistor spark plugs would wear on every intuition cycle, eventually wearing them out. You could pull a spark plug and check the gap. If the plug did not have that much wear, you could regap it and put it back in. Modern spark plugs are made with more durable metal (platinum or iridium). Because of this, they should be replaced every 60,000-120,000 miles, depending on the car.

In older cars, ignition points would wear and affect the engine’s timing. The mechanic would regap the point and then adjust the timing. Most cars after 1995 no longer use a distributor. By removing it, the engine has fewer moving parts (distributor, ignition points, distributor cap and distributor rotor). The engine control model (ECM) can now control the ignition signal. The ECM receives a signal from the crank sensor for spark and the cam sensor injector timing.

As an engine wears, the position of the intake and exhaust valve changes. Cars usually needed a valve adjustment after approximately 15,000 miles. Modern cars use hydraulic lifters, so the engine valves almost always keep a perfect adjustment.

Honda still make a few engines that require classic valve adjustments. The quality of the engine parts and engine design are so good that a valve adjustment is not required until 60,000-100,000 miles. Some Toyota motors require a shim-valve adjustment, but these engines are so good that they are rarely performed until at least 120,000 miles.

Fuel filters also have evolved. When cars used carburetors, just a small volume of fuel was pulled in. Early fuel filters were roughly the size of a large egg and made of plastic. Because they were so small, they got dirty quickly and had to be replaced every 5,000-15,000 miles. In the modern car, the fuel is delivered under high pressure. Because of this, the fuel filter is large and made of metal. Some modern fuel filters are inside the fuel tank and act like a strainer. They should be replaced every 80,000-120,000 miles.

About the only thing that hasn’t changed is the engine air filter. Depending on environmental conditions, the air filter should be replaced every 15,000-30,000 miles. Those who regularly drive on dirt roads should change them more often.

Today’s tune-up is called a “maintenance interval” or “service” by the auto repair industry. The best way to figure out when your car needs one is to consult the owner’s manual. With the complexity of the modern engine, we do not have to make as many manual adjustments, but we still perform computer control tests or adaptations. The evolution of the computer-controlled car has made the engine more fuel-efficient and with lower emissions. I guess you can say we made a trade.

Matt Pataky owns Sunnyvale Foreign Car Service, 15 Pioneer Way, Mountain View. For more information, call 960-6988, email This email address is being protected from spambots. You need JavaScript enabled to view it. or visit sunnyvaleforeigncar.com.

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