With gas prices reaching record highs, the fuel-saving benefits, as well as performance improvements, from a much-needed periodic tune-up have never been more pronounced. However, in today's automotive world of computers, converters, environmental regulations, and rapidly changing technology, exactly what is a tune-up anyway?

Many of us remember those wonderful days when a tune-up meant replacing the spark plugs, plug wires, points, rotor, and maybe the distributor cap, and checking the timing and kicking the tires. For many Sport Truck readers who are tooling around in "seasoned" vehicles, this still holds true. For most of us, however, the points, condenser, and rotor are gone forever, and you won't find a bolt to let you adjust the timing if you look all day.

Today, a tune-up normally means:
Replace the spark plugs and spark plug wires (if applicable)
Check the oxygen sensors for proper operation and replace if needed
Replace the air filter, breather filter, and pcv valve
Change the oil and filter
Change the fuel filter
Check the transmission and replace fluid if needed
Inflate the tires to recommended pressure

A tune-up including these factors can show dramatic results. "Test results show fuel economy improvements of nearly 5 percent from installing new premium spark plugs, such as Bosch's Platinum +4 plugs. Replacing a worn or degraded oxygen sensor in many vehicles, especially pre-'96 trucks and cars, can often save another 5 to 10 percent of fuel. Equally important to the sport-truck driver, this can immediately improve driveability and performance." This comes directly from the Product and Technical Support Specialist with the Robert Bosch Corporation. Other research shows that replacing all worn-out or degraded oxygen sensors nationwide would reduce exhaust emissions more than all other repairs combined.

Reading The Plugs
When replacing spark plugs, reading the old plugs is a good way to determine the engine's general operating condition, and to detect problems. First, it is important to keep the plugs in order with the cylinders from which they were removed. The color and condition of the plug tip is an indication of combustion conditions, and plug tip conditions in a properly operating engine should be uniform for all cylinders. A tan, slightly reddish deposit on the spark plug is normal. Other colors or conditions on the tip may point to fuel, ignition, vacuum, or engine problems. For example, black and fluffy soot on the plug insulator indicates an over-rich fuel condition, which may be caused by a leaking injector or out-of-adjustment carburetor.

White deposits on the insulator typically indicate oil consumption. This may point to a failed cylinder valve oil seal, worn valve stem guide, worn or broken piston ring, or scored cylinder. Any of these failures indicates the need for internal engine repairs. Catching these problems early by reading the plugs can save you money on more expensive repairs down the line. Very-light-tan or white blistered insulators may point to a mixture that is too lean or hot. Clogged fuel injectors may cause excessively lean mixtures. A vacuum leak may also cause this condition with multiport or sequential fuel injection, as well as with throttle-body fuel injection and carburetors.

New Plug Wires Assure Spark
If the "juice" doesn't make it through the wires to the spark plugs, there is no spark, resulting in a dead engine. Engine heat is the primary cause of spark plug wire deterioration, which can lead to loss of continuity, or cracks in the insulation, allowing spark to arc to ground. In off-road applications, buildup of dirt and grime over time can also lead to problems with spark tracking to ground, in which case the spark may be weakened, or some plugs may not fire at all. A new set of plug wires is the best way to ensure all the intended spark reaches the plug.

Premium plug wire sets are normally precut to provide exact original-equipment fit. Bosch's Opti-Layer Mag wire features a stainless-steel core that is reinforced with Kevlar and will not break down like carbon cores in conventional plug wires. The stainless core is sheathed with EPDM inner insulation to stop voltage leaks, and then covered with a 100 percent pure-silicone jacket for lifetime protection.

We tested the resistance of the old spark plug wires against the resistance of the new wires and we found a dramatic difference. The new wires read 0.886 kilo ohms compared with the 8.440 kilo ohms the stock wires read.