Why are plug wires so important for good performance, fuel economy and emissions?
The plug wires or ignition cables carry high-voltage current from the ignition coil(s) to the spark plug. If the plug wires have too much internal resistance or the insulation is leaking, not enough current may reach the plugs causing the plugs to misfire. This can cause hard starting, a rough idle, a loss of power, a big increase in hydrocarbon emissions and poor fuel economy. On 1995-and-newer vehicles with onboard diagnostics II (OBD II), ignition misfires caused by bad plug wires can set a misfire diagnostic trouble code (DTC) and turn on the malfunction indicator lamp (MIL). In areas where vehicles must undergo emissions testing, this kind of problem will cause the vehicle to fail the emissions test. Plug wires should be inspected if any of the systems are present, and when the spark plugs are changed. If wires show any obvious damage such as burned or cracked insulation, chaffing, loose plug boot or terminals, the wires should be replaced. Also, if visible arcing is present new w
