I did my own coil upgrade without a kit. I wanted some something a little more compact with almost a factory appearance. I don’t have many detailed photos but hopefully everyone gets the idea. Enjoy!

I don’t have specifics on the exact parts I used but here’s an idea:
The coil pack came from a late 90s to early 00s Caravan or Grand Caravan.
The coil bracket also came from the same van.
The coil plug from the same van.
A coil bracket from a 4.0 XJ that has a distributor.

These 4 items came from a salvage yard.

First off, the large wiring harness behind the AC compressor and alternator had to be altered and out of way. I rerouted and shortened many wires and cables such as the starter cable and AC wires, alternator wires and engine block grounds.



This is basically the end result. Many wires got shortened like the AC and alternator plug wires. You can also see how I routed the 2 engine block grounds going above the oil pressure sending unit and bolted them coming from underneath compared to coming from above how they were originally. I also shortened the alternator output cable later on.

 

I did this mod and it has been working great.

 

I mocked up the XJ coil bracket in the same location. Then held up the van coil bracket on to check fitment. I had to trim the corner piece so it would clear the camshaft position sensor. Also the bottom edge and tab of the van bracket was hammered flat to remove the step.

XJ coil bracket


Van coil and bracket


Lower corner trimmed to clear camshaft position sensor


The edge that was hammered flat

 

Since the van bracket tab is not flush with the XJ bracket I clamped the two brackets together to use the hole near the vise grips as a starting point. I marked and drilled that hole into the van bracket. Then I marked as best as I could for the second hole to drill and it came out fine. To fill the gap I used a nut as a spacer and also trimmed the bolt later on.

 

I made a bracket from flat metal, about 10 gauge, that I had laying around. This is connected to the top coil bolt and the other end to a stud that holds the ignition capacitor to the engine block. The flat bracket is to help support and keep the coil stationary.




How it would be mounted to the engine block.


Fresh paint. I used rustoleum appliance enamel that I had at the moment.


Mocked up. Notice the notch to clear camshaft sensor.


I also tack welded a flat washer into the recessed around of the bolt hole. The washer is slightly higher that the surface of the bracket, for ease of bolting the flat bracket on.

 

Next I did the harness for the coil. I bought a jumper harness off Rockauto for a 2000 XJ 4.0. For ease I decided to use the factory coil connector off the van. I made my cuts and extended the wires and attached the van connector. After the coil mod was completely installed I ran into an issue. The wires were not routed appropriately and the Jeep did not start. I realized that the wires had to be switched. If you look at the jumper harness all the wires run parallel and connect on the same end of each other. Basically what had to be done was cut the wires, flip one connecter over 180 degrees, and then connect the wires. So in the end it would be, purple to brown, yellow to white, white to yellow, brown to purple. You can see where I cut the red leads down the middle and did the swap. Or you could just buy a premade harness which are sold by ksuspension…lol. But this is my DIY and I wanted to wires cut to length for my application.

Here is what I meant. Cut the wires then turn the red tab connector facing down, then connect the wires straight across. Purple to brown, yellow to white, white to yellow, brown to purple.


Extended wires. This end connects to where the coil rail attached


Van coil plug that I used instead of the jumper plug


The trial and error harness


Cut and fixed harness

 

I don’t have photos of the rest of the install but hopefully there’s an understanding of how everything was mounted. I like how the coil pack sits tucked away close to the engine block. It almost looks factory. Also, I used a new set of plug wires for an XJ equipped with a distributor.

Nicely tucked away


Coil harness with wire loom routed behind dipstick tube. You can also see the flat bracket attached to the stud that holds the ignition capacitor (little black box).





No plug wires from coolant reservoir to engine block. Cleaner IMO

 

Great write up! Looks factory with that bracket. I'm assuming you would need to pull the coil bracket off to get the cam sensor out?

 

This is some great work! Very clean install. I love to see mods that look factory, it's the goal I try for in every mod I do.

Back when I was parting out one XJ to build another, I spent a few hours pouring over wiring diagrams to see if I could put a 2000 Federal emissions (no pre cats) ECU and engine bay harness in my 1999 to get the stronger ignition system. I wish I had stuck with it in order to ditch the distributor and run this setup. That'd be the best of everything - the 1999 down exhaust system, high energy ignition, and wires to the individual plugs for ease of diagnostics.