WHAT’S IN A NAME?
As with nearly anything in this world, the terminology people use to describe something is the last thing to change. The engine “tune-up” is certainly one of those phrases who’s meaning has has changed over the years. Even President Obama has singled out the “tune-up” as a way to conserve fuel and help reduce our foreign oil needs.
President Obama apparently doesn’t know this, but for all practical purposes the “tune-up” is part of automotive history. In fact, most automotive service technicians will tell you that the need for a “tune-up” as we have known it is virtually non-existent for modern computer controlled engines.
A typical motor vehicle of the 70’s and 80’s wasn’t all that different from the early internal combustion engines. You had to have a proper fuel / air mixture which was typically provided by a carburetor. You also had to have spark to ignite that air / fuel mixture at just the right time to provide power. But over the last ten years it’s a different story. In today’s blog post, we’ll describe what made up a typical tune-up back 20 / 30 years ago, and why the word has become basically meaningless today.
In order for an engine to run, you need fuel of course. But an efficient running engine requires the fuel to be properly metered and mixed with air. This creates a perfect mix of fuel vapor that would travel to the combustion chamber and ignited by the spark plug. The carburetor was the device responsible for proper fuel delivery. It consisted of a fuel line inlet that filled a bowl. In the bottom of that bowl was a small tube that led to a “jet”, or a small orifice. The carburetor also had flaps that would allow air to flow past the jets, sucking the fuel through the jet and mixing it with the air as it traveled down the intake manifold to the intake valve. The intake valve would open to allow the air/fuel mixture into the cylinder.
An efficient running engine needed just the right amount of fuel mixed with the air. The carburetor needed to be adjusted so the mixture wouldn’t be too rich or too lean. And sometimes it needed to be adjusted several times a year, as that fuel mixture was dependent on the average ambient temperature, altitude, and a host of other variables. Jets could become clogged, the various linkages could work themselves out of adjustment. the accelerator pump could rip, etc. Additionally, in many cases the fuel filter was a small paper element that was installed right in the front of the carburetor, and that would need to be replaced from time to time.
THE IGNITION SYSTEM:
In these older style vehicles, the ignition system was comprised of several parts. Spark plugs provided the spark that ignited the air / fuel mixture so the engine would run. Each plug was connected by a spark plug wire, and that wire was connected to a Distributor. The distributor would “distribute” electrical current from a single coil through the distributor cap. An Ignition Rotor would spin around the inside of the cap so the electricity would be sent to a single wire. The ignition Coil would supply the spark to the system, and the points and condenser would be responsible for firing the coil.
As you might imagine, this system has a lot of physical parts that need to be adjusted and readjusted. Ignition timing is set by physically turning the distributor in its installed location. The points have to be replaced and adjusted periodically, and the cap and rotor will wear out with all of that electricity firing through it. Spark plugs only lasted MAYBE 15,000 miles, and wires were more than likely replaced whenever the cap and rotor would be replaced. Some distributors had a “vacuum advance” unit that might need to be adjusted or replaced from time to time.
THE ORIGINAL TUNE UP
When a technician performed a tune up, they would replace the spark plugs, inspect the distributor cap, rotor and points for wear (usually burn marks from the sparks they would endure throughout their operational life) and replace as necessary. They would also replace the fuel filter and air filter as both of those items were in the same vicinity. When the new parts were installed, they would then make all of the engine settings, including the adjustment of carburetor linkages, point gap and dwell, ignition timing, etc. A complete tune-up could take a few hours depending on the type of vehicle.
THE TUNE UP TODAY:
The fuel and ignition systems for vehicles of the 70’s and 80’s and today’s computer controlled systems couldn’t be more different. The carburetor has been replaced by direct fuel injection, where injectors spray a metered amount of fuel directly into each cylinder. The distributor type ignition system has been replaced by coils directly attached to each spark plug, a crankshaft sensor informing the computer where each piston is located, and the computer telling the injector when to spray and the coil when to fire the spark plug. Most vehicles don’t even have a fuel filter anymore. Instead of making adjustments to engine settings at every tune-up, the computer makes adjustments many times a second to make sure the engine is running at peak efficiency at all times.
Regular maintenance is very important to the longevity of your vehicle investment. But with today’s integrated systems, the “tune-up” as we know it is a thing of the past. For your convenience, Santos Auto Service has access to most factory recommended service intervals for your vehicle, and we can performed those recommended services to keep your car running great.