Spark plug wires should be inspected at the prescribed service interval and always when the spark plugs have been replaced in the engine. Some models for example the 4.3L V6, 5.0L V8, 5.7L V8, 7.4L V8 contain spark plug wires that runs from the plug to the distributor whereas models like 4.8V V8 models, 5.3V V8 and 6.0 L V8 contain individual coils for each cylinder so they will only contain short plug wires. For access, loosen the front wheel lug nuts and then chocks the vehicle on a jack stand, then pull off the wheels and inner fender splash shields. Initially, perform a surface check using the engine while running with your lights off identifying those spark plug wires which arc or spark. A plug wire can be disconnected simply by holding firmly the rubber boot on it and twirling it and pulling it downward without having to hold the wire. Inspect the corrosion on the inside of the boot making sure that it gives a perfect fit on the spark plug; Trim the metal connector if it has been laid back in order to make a perfect connection. Using a rag wipe the wire down, ensuring that it isn't bent too many times or otherwise damaged. Remove a wire from the distributor cap or coil, inspecting the corrosion and proper fit before reconnecting the wire. Perform the same process on all spark plug wires making sure they are properly connected. If new wire is required it is recommended to get a set of wires appropriate for the particular model of the engine, connect them one at a time restoring the firing order and ensuring the right wire path. In case of the engine has a distributor, then, using a wrench, unscrew the distributor cap screws and lift the cap up while still connected to the wires and then examine the rotor for crack or any sign of wear and if, then replace it. The rotor has to be fitted accurately so that the internal key has to fit into the slot provided in the shaft. Check distributor cap for signs of wear and rust, if it is worn or rusty replace it, after that apply silicone dielectric grease around any terminal before the cap is reinstalled. Carefully connect the spark plug wires to the new cap so that they don't get mixed up and then the cap back to the car then screws it down.
