Diagnosing your Eagle spark plug wires requires a little detective work, but is worth the effort. If you can trace your combustion problems to your spark plug wires, replacing them is quite easy and much cheaper than diagnosing and replacing other components in the electrical system. What are some of the signs that your spark plug wires might be to blame? You should inspect your wires when you notice a rough idle (which might actually be misfires), poor acceleration, a reduction in gas mileage or failure of an emission test that is attributed to too-high emissions or if a fault code shows cylinder misfire. To check out your wires, first look for signs of arcing, which means that the spark is leaking out and jumping to a nearby ground on the engine. Run the engine in darkness, and watch the engine for the sight of little electrical arcs, or listen for the snap-crack of electricity. Spray the plug wire ends with clean water while you run the engine at idle during this test. Or, take a jumper wire and ground the metal part of the screwdriver, taking care to choose one with a well-insulated handle. Touch the tip of the screwdriver to the wire, and around the coil and boots to see if an arc appears between the wire and the screwdriver. Taking the time to do these simple diagnostics can save you large repair bills - after all, why pay a dealership to do these diagnostics when you can order your Eagle spark plug wires here and replace them yourself?