Most Cherokees have a High Energy Ignition (HEI), which include a distributor, distributor cap and rotor system. Installing spark plug wires is a fairly simple repair to perform. The wires are attached directly between the spark plugs and the distributor.
Jeep Grand Cherokee V8 engines use 8 to 8.5 millimeter ignition coil wires. The cylinder order begins in the front right cylinder, when facing the engine. The cylinders are numbered "1," "3," "5" and "7" (front to back) for the right side of the engine block. The left side is numbered "2," "4," "6" and "8" (front to back). The firing order for the cylinders is stamped on the intake manifold. They fire "1," "8," "4," "3," "6," "5," "7" and "2," in a clockwise direction.
Raise the hood and remove both the positive and negative battery cables. Locate the distributor that is mounted on the top rear of the engine block.
Locate the coil post numbered "1" on the distributor and connect the spark plug wire by hand. Connect the other end to the spark plug located in cylinder number one, as described above.
Follow a clockwise rotation to locate the remaining seven distributor posts. The posts are numbered "1," "8," "4," "3," "6," "5," "7" and "2," in a clockwise direction.
Attach the number 8 wire to the distributor post and then to the spark plug. Continue this process until all of the wires have been attached. Be certain to attach both ends (post to plug) before continuing on to the next spark plug wire.
Install the final coil wire that plugs into the top center post of the distributor. Connect the other end to the ignition coil, located on the left side of the engine, attached to the firewall.
Reconnect the battery and test start the engine to determine if the installation was performed correctly. An incorrect wiring pattern will result in the engine misfiring, and should be corrected before operating the vehicle.
