Firing Order: The firing order for the 4.0L SOHC engine is almost always 1-3-4-2. This is crucial information.
How to Determine the Wiring:
The best way to determine the correct wiring is to:
1. Consult your owner's manual: This is the most reliable source. It should have a diagram showing the spark plug wire routing.
2. Check the engine bay: Look for markings on the engine itself, the valve cover, or the ignition coil pack that might indicate the cylinder number for each spark plug. Sometimes there are cast numbers or labels that help.
3. Use a wiring diagram specific to your vehicle's VIN: A repair manual specific to your vehicle's year, make, model, and engine code (found on a sticker usually under the hood) will have a precise wiring diagram. Websites like AutoZone, Advance Auto Parts, or Haynes/Chilton manuals often offer these diagrams, but you'll need to input your specific VIN.
4. Trace the wires: If all else fails, carefully trace the wires from the spark plugs back to the ignition coil pack. Remember the firing order (1-3-4-2) to help you figure out which wire goes to which plug. Be extremely cautious when working near the ignition system to avoid electric shock.
Important Note: Improperly wired spark plugs will cause misfires, poor performance, and potentially damage the engine. If you are unsure about anything, seek professional help from a qualified mechanic. Do not attempt to guess.
