Renix swap question

I currently have a '90 XJ with the renix 4.0. The other day a buddy told me he has a '99 XJ 4.0 low mileage, full engine, t-case, tranny, wiring harness, computer and mis. other parts still attached. I have read several posts doing a similar swap but nothing on a full swap similar to this. Two questions:

1. What is a far price for all of the above?
2. Will there be electrical issues to deal with? and what might those be?

I will be going to his house in the next day or so to check it out and see what exactly is included. Any good tips on problem areas to look for?

Thanks!

The only electrical "issue" will be that you're talking about replacing the entire underhood and fuel control harness. Everything. Plus undefined insrument issues, because your Renix runs the oil pressure and temperature gauges from independent sensors, and the '99 runs the gauges off the PCM. Plus the polarity on the gauges is reversed.

It can certainly be done. Chrysler still offers a stand-alone MPFI conversion for the older carbureted 4.2L engines. That kit is basically the entire injection system and harness for a '94 YJ. So if the factory can sell it as a kit, there's no reason you can't use it as a kit.

It's just a lot of work tracing wiring and figuring out what the toss, what to save, and where to splice.

Why do the swap?

The old Renix motors are better on fuel and while many may argue this are more capable for more power. My old '87 was a lot faster than my new '99 with nearly all the same mods. I used to get 21-24mpg with the renix, the best with the '99 is 19mpg going 65 while drafting others.

I swapped in a 93 motor into my 89 Renix system.
If you want an easy swap just use the new block, intake & exhaust; reuse all your old sensors, computer and accessories.

If your tranny shifts fine, then don't swap it, I wouldn't recommend even swapping the motor unless yours has problems. I also hear 99 motors were cast bad or something like that.

I plan to do a similar swap [93 4.0 replacing an 89 2.5]. I know I will have to move the motor mounts and cut the rear driveshaft but is there anything else I should know. I have a complete donor 93 Cherokee [4.0/5 spd]. I plan to transplant engine/transmission/transfer case into an 89 Comanche. My main concern is wiring. I am trying to avoid swapping wiring harnesses if possible.

Any words of wisdom?

yes, pull all the sensors out of the old engine (or get sensors for an 89 4.0 engine if they're different) and put them in the newer motor. The TPS sensor is the only confusing one to adapt, imo. The coil and distributor will have to be reused from the old motor with the old computer.

You'll also need the new cables to the throttle & tranny for the new motor since they attach differently.

Put the new open system in the old jeep as well and it will cool much better. Just splice the wires for the temp sensor to the new sensor in the thermostat cap.

Re: Renix swap question (update)

Ok, here it is. I am now the proud owner of a 28,000 mile 97 XJ motor. It looks like they pulled the engine and tranny and when they did the only thjing they took off was accesories ie. compressor, H2O pump, alt etc. The fuel rail, plugs, distrib, sensors, plugs (although I will install new ones) and complete wire harnesses are still in place. I also have the computer and a new flywheel.

I have done a lot of things on jeeps but never an engine swap. The problem is I am on an Island in Alaska with all my willing help back home in GA. So I am going to need some verbal expertise from you guys. So is there a write up already done on this? I have seen similar write ups but none that involved swapping the computer, most just swap the block. I am going to be doing all of this work myself with the help of the old manual and the new engine's manual, so if anybody has a write-up or good step by step that would be awesome.

So far I see I am going to need donor throttle and tranny cables because the old ones connect differtly or are shorter. I may wait until later to convert to the open cooling system, is that going to be a problem?

Short version: sensors and flywheel MUST be the same era as the computer, since they are used by the computer to run the engine properly. I included flywheel because the flywheel with the Renix CPS is different than the later flywheel. The later flywheel won't work with the Renix CPS (and you must use the Renix CPS with the Renix computer).

Thanks 4xBob that helps, now on that same note, just so I do not forget anything in the process. I have the computer for that year as well as the flywheel. How many sensors and what type do I need to be sure I have everything before starting this. I have a good idea, I just do not want to miss anything: TPS, CPS (I am assuming this is clutch posn sensor), map sensor (not had to do much with this one so if someone could easily elaborate), beyond that nothing comes to mind, except manifold or headers will Renix work on HO or not? please advise...