Has anyone out there every removed the computer system from their cherokee and replaced it with an aftermarket EFI (electronic fuel injection). I am thinking about taking out all the computer stuff and trying to replace it with an aftermarket EFI. Just wanted to know if anyone has done this, or if it would be better to just upgrade to a different motor, V8 of some kind.
I want to take my Cherokee down to the most basic form. I don't need the computer for anything but running the fuel injection, and I figure someone out there in the aftermarket world makes a bigger better system.

Any help will be appreciated. Thanks.

 

Questions like this come up every so often. So I ask, why? This isn't some complicated European car you're dumbing down to make a track car, it's pretty damn simple electronically. Leave it alone, there is no benefit to remove it.

 

I agree, there really aren't too many sensors. And on top of that I don't know if a aftermarket efi would really give you any performance gains

 

i guarantee an aftermarket efi system would gives gains. a lot. especially if timing tables can be incorporated into the equation. results only growing exponentially by mod.

 

I didn't think you could adjust timing with a computer on a distributer timed vehicle...

 

How much would you bet that guarantee on?

 

There are some piggy-back and full replacement units like MegaSquirt if you're taking the engine outside OE spec. Really no use if you aren't doing a stroker or turbo or something. The 4.0L is very tightly tuned already: It's not a modern engine that can get 100 HP out of a tune, it's a tractor engine that was discontinued because of poor fuel and emissions performance.

(And yes the stock PCM advances timing to a certain extent. If the distributor is indexed correctly, it's actually the ground side on the coil that controls spark. Based on CPS input, the PCM can fire spark anywhere while the rotor is at that cyl's position, which is quite large. Renix ECUs do this to a greater extent with the use of a knock sensor)

 

Thanks everyone for your thoughts I see it has sparked a big conversation. I will look into some options and if I come up with a good one I will post it.

 

Mmkay... Why reinvent the wheel?

 

Well at least he didn't say he was going to remove everything and put a carb on it.

 

It would help if the OP said what year XJ. I imagine a 99 is already a better set up than say a 87. I personally don't see the point.

 

Not really. The Renix is very simple and forgiving.

 

My XJ is a 91

 

pretty sure at least one model year xj had coils.

id bet whatever the opposition wanted. you can't tell me the factory fuel management on a jeep cherokee couldn't be outdone. if so lol welcome to earth.

 

They all had coils. The early ones had distributors until they went to coil packs. Timing is adjusted by the ECT/PCM using the CPS signal as a reference.

And as far as going mega-squirt or the like, I doubt you would see much gain. A little bit with some tweaking, but not much.