Swap guru's: ponder this - '89 renix into a '91 HO???

Here is my delima... $$$ is non-existant for all things Jeep right now (I'm sure a lot of you are in this boat, rowing frantically right behind me!).

I have a '91 that the guy I bought it from yanked out the 4.0/AX15/NP231 for a 350 conversion. He sold the drivetrain and then found a CJ with a 350 and lost interest. His loss, my gain. So now I have an engineless '91. The only smart thing he did was to disconnect everything and leave all of the wiring in tact. The only thing that was cut was the rubber fuel lines that run between the engine and the hard lines. :yelclap:

I came across a FREE '89 2-door sport with the renix/AX15/NP231 in it. Some college kid took it in for a new starter and bailed on it. His loss, my gain. So now I have this XJ with no title, and the parts gremlins stole the grill/front clip and the fuel injectors. :looser: I know I will need to get some new injectors, and from what I've read here, the Ford blue top injectors would be money better spent. I will also need a new starter.

So, here is the big question: Do you see any reason I couldn't put the '89 Renix drivetrain into the '91 body? I would probably have to include the computer. Any other problems? I know you are not supposed to put in an older engine, but where I live in Southern Colorado, there isn't any smog checks to deal with and the local DMV doesn't so much as look at anything other than the VIN number during the registration process.

Now, before anybody hops up on their soapbox, I plan on swapping the entire thing over. I guess that means all of the smog items as I would not begin to know what I could eliminate. Also, if it becomes too much of an issue, then I could always make it a trail only rig with an OHV tag and tow it to the trails. Then, I could yank all of the smog stuff. But for now, I just want a running rig and since I don't have any money to go and buy the right year 4.0 and I DO have a free 4.0 sitting outside, I am seriously pondering this swap.

Thanks for your thoughts and opinions!

sell the 89 and buy a HO motor. less crap to mess with and less factory emissions components..........well........technically there are no emissions components on the HO's other than air in, burn, air out. You got an O2 sensor and that's (simply put) about it compared to the renix setups.

but that's just me. i like stuff with the least parts possible. that's really the only thing i have against renix. that and their slightly smaller aftermarket support, crappy underhood wiring, etc..etc..etc..etc..

Thanks for the quick response. I guess I could yank the AX15/NP231 and then part it out selling off the Renix. Is there much of a market for parting out an XJ like that? Or would I better better off trying to sell the whole thing (without a title) and then buying the 4.0/AX15/NP231 from somebody else? I'm a bolt-on guy and have ZERO experience swapping stuff like this.
Tia!

The block casting was lightened internally for 1991, but no external changes - no trouble there.

You will need to get a new thermostat housing (for the later engine and electronics - but it will drop right on.) You'll need to replace sensors as well, but that shouldn't be a huge problem.

1991-up doesn't have EGR, so you'll have to block that off. You can use a metal plate, or just leave the EGR valve in place and disconnected. Cut off the tube and braze caps onto it to block the ports in the manifolds, or just find plugs to fit the holes (if you do, please let me know what size you got! It looks like a flared tube setup, but I've not been able to figure the size of the thing just yet...)

You'll not be using the knock sensor in the RENIX block - it may be removed easily, and nothing will leak out of the open hole.

I'd suggest getting a new downpipe (from the manifold to the catalytic converter,) as they apparently changed in 1990/1991. Get the RENIX-era one, since that's what manifold you'll be using.

Those are the only real issues I can think of offhand - if you have any more specific questions, ask away! I'll answer you as best I can - this is the sort of thing I'm writing Swappology for. Granted, this is a new spin - most people go forwards, but there's nothing really stopping you from going backwards with a swap... Power to you!

Thanks 5-90! I was thinking of pulling EVERYTHING I needed off the '89 including the exhaust/cat. Would it be easier to swap everything including the cpu, or just the engine and swap out the thermostat and sensors you mentions? The '91 looks like the engine was just pulled and all connectors are there. The '89 is all in place except the injectors. So (fingers crossed), I am really hoping it is plug and play!

yzergod said:

Thanks 5-90! I was thinking of pulling EVERYTHING I needed off the '89 including the exhaust/cat. Would it be easier to swap everything including the cpu, or just the engine and swap out the thermostat and sensors you mentions? The '91 looks like the engine was just pulled and all connectors are there. The '89 is all in place except the injectors. So (fingers crossed), I am really hoping it is plug and play!

Click to expand...

Hang on to the donor - but a simple change of sensors (to be compatible with the OBD-I ECU) and changing the downpipe should be enough, from what I'm thinking. Hell - most of the sensors are probably the same (AMC used GM parts for this, and GM sort of "set the standard,") but if you've got to change sensors anyhow, might as well be thorough.

Mechanically, there aren't a Hell of a lot of differences for you to worry about - the 1991 kept the gage sensor in the cylinder head (holdover from RENIX,) and the sensor in the thermostat housing generates an ECU signal used for fuel trimming and actuating the E-fan.

There aren't any real "smog differences" between RENIX and OBD, save the EGR valve - which I already covered.

Save the donor for in case things get silly, but I don't expect anything like that to happen. If you end up not using them, I may want to talk you out of those RENIX parts for a pet project of mine - and I may be interested in seeing your notebook on the swap as well. Feel free to ask - "in the open," via PM, or via e-mail - if you have any questions. I've got a particular interest in this project anyhow (but I expect it won't be as difficult as it's being made out to be...)

I am doing a similar swap - an 90 renix engine in to a 91 xj 2 door. Here's what I ahve so far:


Injector harness was missing from the 91 so I ahd to swap in the 90's injector harness, which went into swapping the entire engine harness. Rubber plug at the firewall had to enlarged to accomodate the larger renix ECM plug.

Cooling system - closed versus open, not a big deal, just had to relocate the brackets.

The question I am running into is will the engine side wiring harness match the chassis side harness where they bolt together in the firewall at the fuse block? Meaning, did the 90 cherokee and the 91 cherokee use the same configuration fuse block so that 90's part A fuse block/firewall connector will plug into the 91 chassis side fuseblock connector?

Remember to remove the WARNING decal regarding your oil filter thread, or the one time someone borrows the car and takes it to jiffy lube doing you a favor, and the bonehead at jiffy lube puts the wrong oil filter on it - hasn't happened, but I could see it going that way....


I can post more as more develops.

Curt

bossman91xj said:

I am doing a similar swap - an 90 renix engine in to a 91 xj 2 door. Here's what I ahve so far:


Injector harness was missing from the 91 so I ahd to swap in the 90's injector harness, which went into swapping the entire engine harness. Rubber plug at the firewall had to enlarged to accomodate the larger renix ECM plug.

Cooling system - closed versus open, not a big deal, just had to relocate the brackets.

The question I am running into is will the engine side wiring harness match the chassis side harness where they bolt together in the firewall at the fuse block? Meaning, did the 90 cherokee and the 91 cherokee use the same configuration fuse block so that 90's part A fuse block/firewall connector will plug into the 91 chassis side fuseblock connector?

Remember to remove the WARNING decal regarding your oil filter thread, or the one time someone borrows the car and takes it to jiffy lube doing you a favor, and the bonehead at jiffy lube puts the wrong oil filter on it - hasn't happened, but I could see it going that way....


I can post more as more develops.

Curt

Click to expand...

Good point on the oil filter - I hadn't thought of that!

I don't know if the RENIX engine bay harness and the HO are pin-for-pin compatible - but I'd think not. Reason? Isn't the RENIX ECU down by your right knee, and the HO underhood? Or am I misremembering something? That could change things considerably, tho.

I'd probably have used a pair of Weatherpacks and made a new junction - use the RENIX as a subharness and patched it (neatly!) into the HO. Should be quite doable - using either a pair of Weatherpacks, or an Amphenol CPC.

I'd like to see your notebook when you're done as well, if you don't mind...

I had a nice long non-coherent response typed up. Then I realized I was too tired. Then I realized something. I've recently scrapped both a renix and HO XJ, and I routinely canibalize the engine harness parts because weatherpak/metripak connectors are expensive. In any case, I mentally came up with a list of the differences:

Distributor plugs
CPS plugs I think
Flexplate slots are different
Intake Air temp Sensor plug is different too I think
both the idle air controller and TPS...
Coolant temp sensor plug too, and the HO has an extra one IIRC on the back of the head.

Essentially only the bosch style injector plugs are the same.

If you swap the distributor, and get an HO CPS and Flexplate you have a good start. Then, an HO Throttle body with an adapter plate and you're getting pretty warm. Swap out the intake and coolant temp sensors for HO units and good golly the thing might even run.

However, if you can find a cheap/free source for all those good sensors, it probably means you have a head and intake manifold available too. So buy that, a headgasket, and bolt it up and you'd be ahead of the game.


But no easy way out. Unless you go with megasquirt or something simliar. But I guess that's not "easy" but for me it's the route I'd take. Or rather, the route I'm taking currently.

The ECU location is different, but remember the location of the ECM won't matter as its only pulling power from the fuse block. I have the other fuse block, it will just be a PITA to change all the silly crap out.

bossman91xj said:

The ECU location is different, but remember the location of the ECM won't matter as its only pulling power from the fuse block. I have the other fuse block, it will just be a PITA to change all the silly crap out.

Click to expand...

I'm sure it's different - but which side of the firewall the ECU is on will change the bulkhead connector (if you're running signals both ways, or just running fused power out, or just running fused power from the PCM, or ...)

One of these days, I'll get to checking on that idea as well. I've just got a few other things to do before I start to focus on electronic swapping...

see that's just to much hassle for me. i would still stick with the idea of selling the renix stuff and getting yourself a HO engine. personally i just don't understand why you would want to go through all that work when a HO engine would be plug and play.

Thanks guys for all of the input! Definatly stuff to ponder.

As to the reason why I'd want to stuff a Renix 4.0 where a HO 4.0 was is simple... $$$. I have a full Renix sitting outside and have heard that the Renix offers more low end torque. Since the years are close, I was thinking that a bird in the hand... especially since I have the ENTIRE source vehicle.

I put a 93 HO into my Renix system, essentially you are doing the opposite.
Here is my write-up of the swap:
http://www.terrainstompers.com/forum/viewtopic.php?t=14
It should be pretty straightforward, with a few minor modifications.

Okay, here is an update on my swap - YZERGOD, sorry if I stole your thread:


Decided to stick with the 91 engine and ecm. I am taking parts of the 90 harness i.e., injector harness and soldering into the 91 harness. I know TPS will be different. Hoping the the CPS connector is different, I can just change the connector. Flexplates, etc., don't sound like part of the plan for me. EGR will need to be plugged off - no problem. I need a 91 instrument cluster, the 91 I am puitting everything into didn't have it -90 connector is different.

you should just swap the ENTIRE FRIGGIN WIRING HARNESS out of the 89.

you can do that WAY quicker than you can resolder, splice up hack up and fawk up the 91.

use the cable driven speedo from the 89, use everything!

having a fully functioning renix system is awesome. I'm on my second non-renix XJ, and I miss the renix.

renix > ho.

CheapXJ said:

having a fully functioning renix system is awesome. I'm on my second non-renix XJ, and I miss the renix.

renix > ho.

Click to expand...

Why do you like the renix so much? I have had a lot of people ask why go with a renix over another '91 4.0.
Thx

If you live in Colorado, the swap is illegal if you swap the computer. You can swap forward but not backward. I would keep your HO electronics, intake, exhaust and TB. It will make things a ton simpler. Remember that the flex plates are different and have to match the computer.

old_man said:

If you live in Colorado, the swap is illegal if you swap the computer. You can swap forward but not backward. I would keep your HO electronics, intake, exhaust and TB. It will make things a ton simpler. Remember that the flex plates are different and have to match the computer.

Click to expand...

As I posted in my original thread, I am fully aware of the legal ramifications and if need be, will slap a $15 Colorado OHV sticker on it and tow it to the trails. I already tow my TJ to Moab and other places.

Also, my '91 HAS NO ENGINE, TRANNY, OR T-CASE! So, there is nothing to keep vs. not except the cpu.

And, IMHO the local DMV would be less likely to question another 4.0 under the hood as opposed to a chevy 350. We do not have any type of smog checks here and the DMV guy only verifies the VIN. Legality aside, I could easily get it registered in Colorado.

My question is would it work without a lot of hassle or should I sell the '89 complete and look for another '91 to drop in?

Thx eace: