Assuming you have the 4.0L Inline-6:
The firing order is 1-5-3-6-2-4.
To determine the correct wire placement on your spark plugs, you'll need to:
1. Identify the number 1 cylinder: This is usually marked on the engine block itself, but if not, a diagram in your repair manual will help. The number 1 cylinder is typically at the front of the engine on the passenger side.
2. Follow the firing order: Starting with the number 1 cylinder, trace the wire to the distributor cap (if equipped) or directly to the coil pack (if equipped with coil-near-plug system - less common on 91's but possible). Then, continue in the 1-5-3-6-2-4 sequence. Each number corresponds to the respective spark plug.
Important Considerations:
* Distributor Cap: If your Cherokee uses a distributor, the numbers on the cap should correspond to the cylinder numbers. Make sure the rotor is pointing to the correct cylinder when you are connecting the wires.
* Repair Manual: A factory service manual is invaluable for accurate diagrams and specifications.
* Coil-Near-Plug: Some later model year XJs might have a coil-near-plug system, simplifying the wiring.
* Photographs: Before disconnecting anything, take clear photos of the existing wiring to aid in reassembly.
If you have a different engine in your 1991 Jeep Cherokee (highly unlikely but possible), please specify the engine size and I can provide more accurate information.
