Swap

[Austen]

Hello I am new to the forums, I own a 1988 Jeep Comanche pioneer base model and last night I had purchased a Jeep Cherokee sport to swap full drivetrain... any recommendations?

[IDMJ]

Tons of info here. Do a search. I found lots of answers to my questions before I even asked them

[Dzimm]

What year XJ?  

[Austen]

It is a 1996 Cherokee sport 

[Jeep Driver]

Recommendation #1- Don't use a '96 as a donor. 

[Dzimm]

Ok so the problem you are going to run into is you have a Renix electrical system in your MJ and an HO electrical system in your XJ.  

 

Whats wrong with the drivetrain in the MJ?  

 

You'll have to do some research on the two electrical systems and decide which one you want to use.  The HO is considered a superior system but many people will argue that Renix is better.  

 

 

[Austen]

Well the Comanche is a 4 cyl 4 speed 2 wheel drive so kinda wanted to swap just because of that and the engine in the comanche blew a ring and head gasket and already had 235K on it so I bought the Cherokee for $300 and decided screw it why not 

[Dzimm]

29 minutes ago, Jeep Driver said:

Recommendation #1- Don't use a '96 as a donor. 

This is a good recommendation for sure.  96' is a mixed year of stuff because of the conversion to OBD2.  It can be hard to determine what is what due to so many changes and randomness in parts that were used buy Jeep in that year as they tried to use up stock of old parts and transition to new.  By no means will it be impossible to swap stuff over but it will be more difficult.

[Dzimm]

1 minute ago, Austen said:

Well the Comanche is a 4 cyl 4 speed 2 wheel drive so kinda wanted to swap just because of that and the engine in the comanche blew a ring and head gasket and already had 235K on it so I bought the Cherokee for $300 and decided screw it why not 

In that case, you will need to swap everything over from the XJ.  

[Eagle]

9 minutes ago, Dzimm said:

You'll have to do some research on the two electrical systems and decide which one you want to use.  The HO is considered a superior system but many people will argue that Renix is better.  

 

 

Regardless of which side of the HO vs Renix debate you come down on, 1996 is almost without debate the worst year for the HO. 1996 was the first year that Jeep moved from OBD-1 to OBD-2, and they did it only because it was mandated by the federal government. They knew they were coming out with a significant overhaul of the platform for model year 1997, so the 1996 with OBD-2 was a kludge. Some might regard it as something else, the vernacular description of which involves something about clusters and sexual acts.

 

If I were using a '96 as the base for a swap, I would swap in the mechanical components and maintain the 1988 Renix electrical and fuel system. At least that way you'll know what you're dealing with.

[Dzimm]

13 minutes ago, Eagle said:

If I were using a '96 as the base for a swap, I would swap in the mechanical components and maintain the 1988 Renix electrical and fuel system. At least that way you'll know what you're dealing with.

The truck is a 4cyl so he'd need to source a bunch of other parts to retain Renix and use the 6cyl.  

 

16 minutes ago, Eagle said:

 

Regardless of which side of the HO vs Renix debate you come down on, 1996 is almost without debate the worst year for the HO. 1996 was the first year that Jeep moved from OBD-1 to OBD-2.

Agree with this completely.  To get the truck back on the road for $300 it's a pretty good option though, and honestly selling the extra parts and scrapping the carcass that money can easily be recovered.  The OP just needs to be aware the electrical will be a pain sometimes.

[Austen]

Quick question, did AMC ever make engines for Jeep Comanches because they went out of business/bought out in 1988 and my comanche is a 1988 and has AMC badges everywhere, key, valve cover, and vin plate 

[Austen]

And was made at the Brampton AMC plant but isn’t that in Canada? And my vin says 1 so that means made in America...????

[JeepSchmidt O'Guinness]

With all the headache of 96, it was the most produced xj.... 

 

@Eagle; If i recall correctly, the 96 block doesn't have the distributor, its on the the injectors. 

[87MJTIM]

29 minutes ago, Austen said:

Quick question, did AMC ever make engines for Jeep Comanches because they went out of business/bought out in 1988 and my comanche is a 1988 and has AMC badges everywhere, key, valve cover, and vin plate 

1988 was the changeover year. The sale to Chrysler occurred mid- year. Early models would be all AMC. Later models would have a mixture of parts. My F-I-L bought an 88. I always laughed at it because it had some AMC and Chrysler emblems on it. 

[Eagle]

1 hour ago, Austen said:

Quick question, did AMC ever make engines for Jeep Comanches because they went out of business/bought out in 1988 and my comanche is a 1988 and has AMC badges everywhere, key, valve cover, and vin plate 

 

Yes. The Jeep 4.2L, 4.0L, and 2.5L engines were AMC engines. That engine family began in 1964, as a 232 cubic inch, carbureted in-line six that was advertised as "The six that performs like an eight." (Which was more than a little optimistic, but they were and are great engines, and with minimal care will easily keep running for 300,000+ miles.

[Pete M]

whatever you do, do NOT throw away anything from the MJ.  the 2.5 specific parts (like the throttle body, injector, etc) have become harder to find.  

[Eagle]

21 hours ago, JeepSchmidt O'Guinness said:

 

@Eagle; If i recall correctly, the 96 block doesn't have the distributor, its on the the injectors. 

 

Did you mean on the spark plugs? I don't think the 2.5L ever changed to coil pack ignition. The 4.0L XJ didn't get it until the 2000 model year.

[dasbulliwagen]

As was said, if you continue with the 96, youll need to swap the entire XJ wiring harness, including the interior wiring along with cluster, radio, HVAC and all computer modules. Youll also need to modify the radiator core support for the 4.0 radiator, swap over all accessories, exhaust, sensors, evap system, and then modify the tail light wiring harness to match the MJ, and swap in a 91-92 fuel pump assy. Youll then need to have your rear driveshaft shortened to fit the new drivetrain as the XJ one will be too short. This is all in addition the the engine, trans, transfer case and front axle. If your original rear axle gears don't match the XJ ones, youll also need to weld on new spring perches to the XJ rear axle to make it work on the MJ. Its a big job, but not impossible. And by swapping EVERUYTHING over, youll keep wiring issues to a minimum, assuming they are all in usable condition.

[schardein]

This is not a project I'd be willing to tackle, but wouldn't it be possible to use the 96 engine, but source an OBD1 harness and sensors from a junkyard engine?  Basically, any 91-95 4.0 engine?  Yes it adds to the cost since those parts would have to be bought, but I would think a lot less headaches staying OBD1 but still saving some money using an engine already on hand.

 

I seem  recall the 96 4.0s got some changes to reduce NVH (noise, vibration, harshness) and I think a main stud girdle?  But I think you could bolt on all the older sensors, that is if the 96 sensors aren't compatible with the OBD1.

[schardein]

I've actually used a 1996 throttle body on both my 91 MJ and 91 XJ.  The MAP sensor is mounted directly on the throttle body, so you delete one vacuum line and modify the wire harness to be a little bit longer.  Cleans up the firewall a bit.

[All around mj]

For the radiator core support, if it’s just the top that needs to be modified, you could do what Tyler did for the front end repair on bleepin Jeep. I’m not sure where the ecu is mounted on the 96’ but if it is under the hood on the driver side like earlier HOs that would also provide the mounting holes for the ecu. Best of luck. I will see if I can find the wiring harness swap info I used on my mj.

[All around mj]

https://comancheclub.com/topic/18588-xj-dash-harness-to-rear-mj-harness-wiring-guides/#comment-191227

 

See if this helps.