swapping a 4 banger for a 6

This will be my first engine swap if I I decide its a reasonable project. I have a wrecked 88 with a new crate motor in it and a high miliage 96 xj with a 4 cylinder. The 88 had an automatic, and the 96 is standered. I plan on keeping the clutch, but know I will need a new manual transmission/transfer case. I plan on taking the entire wiring harness and ECU from the 88 and reinstalling it all in the 96. If anyone has done a similar swap, or knows of problems that I will run into I'd apprecaite whatever knowledge is out there. Also if I think its going to be beyond me does anyone want to by a jasper 4.0 with about 25,000 miles?

If you are prepared to swap the entire wiring harness, then you shouldn't have any surprises. But it's a LOT of work. When you say "entire" be sure that's what you mean, because the mid-90s Chysler wiring is a lot different from the 1988 AMC wiring, so you will literally need to swap over everything. Also the instruments, because the 88 used a mechanical speedo and the 91 and newer have an electronic speedo. The 88 wiring harness won't have a feed to the speedo, and the polarity on the instruments is reversed.

four11outback said:

I plan on taking the entire wiring harness and ECU from the 88 and reinstalling it all in the 96.

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Does yours state have OBDII/IM testing. Yes? - Then it will fail.

If you don't have to worry about that, then I guess you could do that, but why? Swap then engine - great idea, but use a 96 PCM and wiring harness. You will save yourself time and problems keeping the control a 1996.

If I upgrade transmissions, what is the best and readily available. I am looking for another 5 speed.

I am assuming its the ax5 you have on the 96 since its a 4 popper. The factory 5spd for jeeps after (88 I think) is the Aisin-Warner AX-15. The ax5 is light duty and wouldn't handle the 4.0. Latest model jeeps came with a 5 speed made by NewVenture Gear. The AX-15 is not the most durable tranny in the world by my opinion but a fresh one done right will be reliable enough and theyre pretty common since they were put in various 4.0l jeeps and Dodge, Toyota light trucks (though these are not adaptable). Is your crate 4.0 a HO or non-HO model with RENIX computer? You could stick with the RENIX system in your 96 unless your state wants to plug the comp into an OBD2 reader. If your state has this requirement than you will need a wiring harness and comp from that era, from another jeep to hook up the new comp and harness to the old model 4-0 (everything should fit all right though). The gauges I am unsure what inputs they need or how they wire up. Not to mention the exhaust which need a little adapting after the header to fit it all. You could of course cheat by registering the 96 as the 88 but I DON'T think thats a good idea. Speak to someone who has first hand experience though. I believe someone recently (old man???) mentioned this.

I am not too worried about the emmisions in New York or their OBD2 testing, I know a few shops that are lienant around these parts. As for the exaust, I planned on taking the whole system off my 88 because that is less then a year old. Where can I get new motor mounts, or can I reuse the ones off the I-6.

You can transfer the 6-cyl mounts with the engine, if they're in good condition. The "frame" of the XJ didn't change the way the engine monts between 88 and 96.

The lads make a good point about emissions, though. You may know a lenient shop now, but the system could change tomorrow. '96 was the first year for OBD-II in the XJ. The 88 Renix system isn't even OBD-I ... it's a proprietary system that doesn't store trouble codes and doesn't mate up with standard OBD-I or OBD-II scanners.

You might be a lot better off keeping the 96 wiring and just finding a 96 or 97 6-cylinder engine room harness to handle the engine. You can use a 96 6-cyl throttle body on the 88 intake manifold. You'll have to adapt the mounting bolt pattern, but then you'll have the correct throttle body and sensors to mate up with the 96 electrical system.

You also won't have to rip the dashboard apart to mount the Renix computer under it

If the "system" changes, you would likely be "grandfathered in" and the old standards apply to you right. Of course you live in the state that elected Hillary . Logic need not apply. Rather than beating around the bush, go to the "lenient" shop, when its not busy, where you know the owner and be nice and ask if the computer is checked or if they just check emissions and see if the Service light is on. Ask what issues might be involved with installing a non-OBD computer and engine into a late model car but that it is a similar motor and will comply with emissions standards and be equipped w/ a cat, etc.