The ignition coil on the 2004 Ford Taurus takes the 12 volts of electricity created by the vehicle's electrical system and turns it into a high-voltage current. It then distributes the current among all the spark plugs, via spark plug wires. Over time, heat and other environmental factors can cause the coil to fail. When this occurs, symptoms include rough idle, poor acceleration or even not starting. Replacing the coil on this vehicle is a task the home mechanic can handle.
Open the hood of the Taurus and disconnect the negative battery cable from the battery, using the ratchet and socket.
Look at the engine and locate the ignition coil. The coil is located at the front of the engine compartment attached to the driver's side of the engine. It is easily identified by the six large spark plug wires attached to the top.
Remove the main input wiring harness -- the oval-shaped plug on the right of the coil -- from the ignition coil by pressing the locking button and pulling the plug upward.
Locate the radio interference ignition capacitor -- the cylindrical component on the right of the coil, approximately 1 inch long. Unplug the connector directly below the capacitor by pressing down on the locking tab and pulling the plug out.
Locate the radio interference ignition capacitor bolt directly below the capacitor. Loosen and remove this bolt with a ratchet and socket, then pull the capacitor from the coil. Save the capacitor for use on the new coil.
Look at the top of the coil and notice where each spark plug wire is plugged in; there are numbers from one to six. Label each spark plug wire, using masking tape and the permanent marker, with the number of the socket into which it is plugged. This assures that the proper ignition firing order is maintained.
Remove all six spark plug wires from the coil by squeezing the locking tabs and pulling up on the base of the wire. Slightly wiggling the wire while pulling it may help loosen the wires.
Loosen and remove the four ignition coil bolts, with a ratchet and socket, and pull the coil from its mounting bracket.
Place the radio interference ignition capacitor to the new ignition coil, and hand-tighten the bolt.
Tighten the radio interference ignition capacitor bolt to 45 to 61 inch-pounds, using the micro torque wrench and a socket.
Place the new ignition coil on its bracket in the engine compartment, and tighten the bolts to 45 to 61 inch-pounds, using the ratchet and socket.
Apply a light coat of dielectric grease on the spark plug boots, where the spark plug wire is attached to the coil.
Plug all six spark plug wires into the ignition coil, making certain to match the numbers labeled on the spark plug wires to the numbers on the ignition coil. Listen for the clicking sound of each spark plug wire locking onto the coil.
Plug the radio interference ignition capacitor and main input harness into the new coil. Listen for the clicking sound to indicate they are locked into place.
Place the negative cable end back onto the negative battery terminal, and tighten it with a ratchet and socket.
Close the hood of the Taurus.
