Over time, most automobile owners become accustomed to the sounds produced by their vehicle. Therefore, a sudden change in the sound of the engine is quickly noticed. When an unusual noise is accompanied by a drop in vehicle performance, it is time to inspect the vehicle for a potentially faulty component.

Unfortunately, some car owners jump to an early conclusion and misdiagnose their own vehicle performance issue. An incorrect diagnosis can become costly if replacement parts are hastily purchased and the problem is not solved. To avoid wasting money, vehicle owners can first test certain electrical components to determine if they are operating within recommended specifications.

Spark plug wires

In some passenger vehicles, the wires connected directly to the spark plugs do not contain a continuous strand of metal. Instead, the center core of many spark plug wires is made of carbon, making the wires vulnerable to engine heat. The non-metallic core is designed to prevent electrical signals from interfering with other ignition components. The carbon core is, nevertheless, capable of transmitting electricity that can be measured.

Resistance is a measure of how freely electricity flows through a substance. Resistance is measured in ohms and can be detected by a small test device referred to as a multimeter. It sounds counterintuitive, but a spark plug wire should have a relatively high resistance level.

To test your spark plug wires with a multimeter, remove only one wire at a time. Touch the two multimeter test probes to the opposite ends of each spark plug wire. The resistance should be within the acceptable range for your specific vehicle.

Engine coil

The coil is essentially a transformer that converts power from the car battery into energy for the spark plugs. The coil contains both a primary circuit from the battery and a secondary circuit to the spark plugs. After removing the attached coil wires, the resistance of the coil itself can be tested with a multimeter.

The circuit from the battery must have relatively little resistance, but the circuit to the spark plugs should have a much higher resistance. The two circuits are tested separately by touching the two multimeter probes to the exposed coil connectors for each circuit. The meter readings should indicate that the coil resistance is within the appropriate range for your specific vehicle.

A technician at an automobile repair shop can quickly test the coil and spark plug wires if you don't possess a multimeter or if you lack the time to research the resistance levels for your specific vehicle. Check out http://soundsideauto.com/ and contact a car repair service for more advice on the various components that can affect engine performance.