bentnotbusted

wise or not, you don't have any choice. You CAN NOT use the flexplates you have, it won't run. You'll need to get an 87-90 flex plate.

zip, zilch, nada. Somebody may enlighten me as to some small tidbit that I've forgotten but I don't think an '89 has any mopar in it at all (pentastar on the key maybe, lol). By the '90 model year a few bits and pieces (brake calipers for one) started to sneak in, with the chrysler electronics coming in '91. Kind of ironic really given how many other manufacturers are in there. Chev steering column, alternator, and some other stuff here and there. Ford distributor and retractable underhood light (if equipped). The previously mentioned Aisin transmission, which I too will vouch for, I'm a die-hard mopar guy as well and I actually swapped out a t-flite for one in my truck. And, of course, the Renault/Bendix fuel injection system. It's an odd mismatch of pieces really, but it's all dead reliable with a little basic maintenance. I DD my car in the summer for the fuel mileage but our winter DD's are an '87 XJ with 320K kilometers (200K miles) and my MJ with unknown mileage well in excess of 500k Km. Both fire up on the first turn of the key, regardless of how cold it gets.

Never bothered putting it in when I originally put the AW4 in years ago but I threw it in when I did the re-wiring this spring. Really, really glad I did. It stayed in "power" until the first time I tried driving on snow covered roads in 2wd :eek: Helps out quite abit to be able to lug it down a bit more on the hills. I'm actually finding the combination of the lower bottom end torque of the HO motor and being able to rev it lower a bit better in the snow.

Depends on your particular case but in some cases the shocks may be the limiting factor in suspension droop. Disconnecting the shocks with the axle at full droop and unsupported may result in a bit of sudden unexpected axle movement. I usually support the jeep on the frame (just behind lower control arm brackets in front, just ahead of spring hangers in rear), then support the wieght of the axle on a floor jack.

Completely true that you would have to re-wire the entire truck to retain the OBD1 control system. Defineately worth mentioning though that, with a few modifications, you can run that engine with the Renix system. Covered on here not long ago: viewtopic.php?f=2&t=27947 I've been running my Renix/HO hybrid since July and it works great, no issues whatsoever. I've even been fortunate enough to be able do get the thing hooked up to a renix compatible scanner and verify that everything is indeed reading and operating as it should, the ol' renix brain is none the wiser that anything has even changed.

Defineately not the case. Contrary to popular myth the deletion of the power/comfort switch had absoluetely nothing to do with Renix vs OBD1. The switch carried over into the '91 model year and possibly the '92 year. (My '91 had one my '93 didn't).

I almost slipped up on this one. You left out an important detail. What transmission do you have? Or more specifically is it a column shift auto? If so I'm pretty sure you're going to be limited to one from an '86-90 MJ with column shift if you want a direct swap. Not sure if these came in tilt versions or not. If it's not column shiftr you'll also be able to use '84-'90 XJ columns as well. Lots of those in tilt for sure.

Have you followed the proper, comanche specific, brake bleeding procedure? Seriously, there is one and you won't get decent back brakes if you don't follow it. Search for brake bleeding procedure on here and you should find it.

Not tremendously useful information but hey, thought I'd throw it out there anyways. Numerous times I've come across people looking to convert thier 2.8 or 2.5 MJ to a 4.0 and invariably the topic of using an XJ wiring harnes comes up and the fact that you have to modify the taillight wiring to make the XJ harness work. Right? Not 100% it turns out. Me and the better half were driving along in her XJ Wagoneer the other day and she mentioned how her tailights seemed brighter than her other XJ. They are. Because they use 2 marker light bulbs like an MJ! MJ and XJ Wagoneer taillight wiring would be the same. So there you go, if your looking for an XJ donor for your MJ 4.0 liter swap keep an eye out for Wagoneers and save yourself one little tidbit of extra work.

If he puts his renix stuff on a newer 4.0l I doubt he will gain much power,also his renix stuff won't just bolt on to a HO head so he would have to use his head which probably has a blown head gasket and maybe other issues or convert his truck to HO manifolds As long as the only renix stuff he uses is the sensors and mounts (as in he does do the manifold conversion), there would indeed be a very noticeable difference in power. I've had the oppurtunity to sample numerous variations of the 4.0 over the years (3 stock renix's, 1 lightly modded renix, 2 stock HO's and now the HO/Renix hybrid). I'd gladly challenge anyone to differentiate powerwise between the Hybrid and a full HO. Keep in mind though that the power comes in a completely different RPM range. While I thoroughly enjoy the added top end power I do sometimes find myself missing the low rpm grunt of the renix motor. One hill in particular in my daily commute the renix motor would pull up in OD at 1600-1800rpm, HO motor has to downshift to 3rd to maintain the same speed. Also since we seem to have gotten into a bit of discussion on blocks and such I thought I'd throw in my $0.02 on that topic as well. Only really applicable for someone building up a motor (or considering keeping thier current one I suppose). I had the oppurtunity to tear down a few well abused 4.0's this summer and observed first hand one of the major differences in the various blocks. The High nickel alloy of the renix era block is indeed super hard! The 300k '91 block out of my XJ showed significant cylinder wall wear as I expected. The 500+K renix block out of the MJ still has visible cross-hatching the full length of the cylinder walls, even in the cylinder with 2 broken rings. I had heard that the blocks were harder but I was truly surprised to see the real-world difference.

You do not need to re-wire your whole truck. You do not need to live with mismatched intake ports. It's entirely possible to drop the entire HO engine in with almost no wiring mods at all. Use the HO manifolds (and exhaust down-pipe as previously mentioned). You'll have to adapt the Renix TPS to the HO throttle body and swap over all the rest of the sensors. One of the temp senders gets relocated to the thermostat housing so the wiring for that will need to be re-routed. Someone makes a kit to adapt the TPS (Hesco?), but if you get creative you can do it yourself. You'll also need the Renix Distributor. HO oil filter interferes with the EVAP canistor so you either have to swap the filter adaptor or relocate the canistor. You'll need the HO vacuum lines and airbox as well as the HO throttle cable. There's some debate, by the way, as to whether or not the HO blocks are threaded for the knock sensor, my '93 block was. I think probably the most difficult part was dealing with the different fuel lines. I used some aftermarket line and fittings to adapt the HO fuel rail to the renix lines. A friend of mine running a very similar setup fabbed brackets to retain the Renix feul rail. I've probably forgotten something here but this is how I did mine. Way easier than ripping the entire cab apart (in my opinion anyway), and it works great. edit: yeah what jpnjim said. And I forgot the alternator (and brackets). Oh and it's still only one TPS with an auto, it just has two plugs.

No. Because they are CHEROKEE floor pans. Cherokee seats mount directly to the (flat) floor. This is also why your cherokee seat brackets don't seem right. You may want to do some searching on here regarding seat swaps.

That would be these guys: http://stores.zmjeeps.com/Detail.bok?no=146659 They claim that the same 1 piece (per side) floor pans will fit XJ's and MJ's. Flat out lie. Period.

That would be good.. if they weren't liars. It really pisses me off how careful we, as MJ owners, have to be when shopping for parts. Those are XJ floor pans! They DO NOT fit! The front half pans in the first link may mostly work, but you'd still be on your own for the part the seat mounts to. Back half looks like XJ to me as well and would be completely useless. Might want to ask thes guys if they've actually ever seen an MJ floor. I my self had always read that the floors were only slightly different and that you could use part of an XJ floor pan. After re-doing my floor last year I would have to say "slightly different" is a stretch. Maybe about the front 1/3 is the same. I had a complete new XJ pan on hand when I started mine, but so little of it was useable that I couldn't bring myself to cut it up. BTW as far as I know there is no source for proper MJ pans.

Not sure where you got that info but I assure you it's wrong. There are 2 limiteds here in my driveway and they both have factory rear swaybars.

Defineately not a fan. I get the theory and all, but I'm not confident enough in the long term reliability of automotive electronics to have anything but a direct mechanical link between my foot and the brakes. Thought I was going to have to change my tune a while back but instead I got a very firm reminder of how right I was. When I was working for the towing company one of my projects was replacing the company's light duty wrecker. The old unit was a '97 Dodge 1 ton, 12 valve cummins, 5spd, with rear drums and no ABS. We purchased a 2002 Dodge 1 ton, 24 valve cummins, 6spd, with rear disks and ABS and switched all the gear over from the old truck. It didn't take long to actually notice the benefit of the ABS as the old truck had a tendency to lock up the front wheels on loose surfaces when loaded. I had the ABS kick in several times on the new truck under similar conditions and it worked very well. Then one day I had just dropped off a car after a 3 1/2 hour haul and was heading home empty. Coming up to a set of traffic lights I step on the brakes, the ABS kicks in, and 8000lbs of towtruck just keeps on sailing :fs1: Further pedal pressure has no effect and the vehicle in front of me is growing closer at an alarming rate. Now being that I haven't relied on ABS my entire life I quickly try pumping the brakes. This fortuneatley results in the ABS light popping on and the brakes reverting to non-ABS. I got stopped with about 4" to spare. I can still see the look on buddy's face in front of me looking out the back window of his half ton. :eek:. So I pull over and stop to collect myself for a few moments and when I start the truck back up to continue on my way the ABS light is back off. So I tentatatively bring the truck up to speed and try the brakes. Same thing, ABS kicks in but almost no stopping. Release the pedal and re-apply and the light comes back on and the brakes work. I stopped and yanked the ABS fuse right there. To the best of my knowledge it has not been re-installed.

OK, so I've got a few questions for you guys. First off I've been trying to find out if a the output shaft on a BA-10/5 is the same length as an AW4. I know it's 21 spline but not if it's the same length. Reason I ask is we recently bought an XJ with a BA-10/5 and 231 and we'd like to swap in a 242 if possible. Second question, is there any way to tell, short of actually taking it out and counting the splines, whether an AW4 is 21 or 23 spline? Any known difference in casting or part numbers on the tranny or t-case? I had always heard that the change was for the '91 model year, but just read in another thread here that it was actually mid year '90. This seems entirely logical to me as we currently have 2 '90 XJ's and you can actually see how things were gradually changing during that model year. Both have the c-clip rear, but one has the old style front hubs/brakes and the other has the newer style. A while back I smashed my 23 spline NP242 in the MJ on a rock and had to replace it with a 231 because I assumed the 2 spares we have ('89 and '90) were 21 spline. I really miss the 242 in the MJ for winter driving and it would be sweet if the '90 was in fact a 23 slpine, but I'm not gonna yank it out in my driveway in the snow just to count the splines.

Can't get much more jury-rigged than that. Sure you can. We recently bought an XJ that the previous owner informed us the CAD had been "dealt with". So after addressing a few other issues it had we headed home from the shop in it at the height of one of the worst snowstorms we've had around here in quite awhile. Shortly into the trip it became obvious that there was a problem as with the occasional pop from the front end. We live on a dead end, dirt road that goes uphill at 15-20 degrees from the time you leave the pavement till you get to our house (about 1/2KM). Snow was about a foot deep in the road by this point and we lost front drive twice and had to back up and try again. Now the snow was thick and heavy and the Jeep has 4 brand new studded winter tires on it. So (aside from the disconnect) the problem wasn't traction but wheel-hop. As we finally did make it to the driveway I was in 4-low, first gear crawling along at a very fine line between stalling the engine and breaking into a massive shuddering hop. I would think this would be putting quite a strain on the disconnect. Got the Jeep in the garage here at the house and pulled the CAD to find: No fork at all, and a plastic cable tie around the axle shaft :nuts: Had things not already deteriorated to the point they have I'd apologize for hi-jacking, but what's the point really now?

We recently scored a nice XJ for super cheap because it had the same problem. Turned out to be a dead plug :yes: I'd definately make sure it's firing on all 6. An injector stuck open could likely cause the same symptoms though. Not sure how rich you'd have to be running to get the gas in the oil otherwise.

Finally got around to this today. Big thanks to you guys for the info. I have brakes again! :clapping:

Thanks a ton guys, I never knew there was a special procedure. I'll give that a try and see what happens. Odd I've never had this problem before though, especially considering this is the second time I've replaced this particular line.

So I'm having a bit of an issue with the rear brakes on the MJ. Just changed one of the hard lines going into the load valve because of a small leak at the fitting. I was under the impression that this was the cause of my pedal going soft. Apparently not :shake: I spent the better part of an afternoon (and a full quart of brake fluid) trying to get a decent pedal but it's just not happening. Brakes will pump up after 4 or 5 pumps everytime but let off and hit them again and you're right back where you started. I've bled them at the wheels, at the top of the load valve, and at the master. I've replaced almost every brake line on this truck now at some point and I've never had a problem like this. Anyone got any suggestions? Know anywhere in the MJ brake system that tends to trap air? Could it be a problem with the load valve? We're actually leaning toward the master cylinder but I'm just curious what the experts think. I might get aggravated enough tonight to throw a master on it anyway though.

Don't Do IT!! LOL I was gonna post that on the NSJC board but I'll probably get more support here ;) Seriously you should just trade me for my old BFG series XJ, I'll even throw in a good replacement motor for the toasted one that's in it now. I'd love to see another MJ in the series but it'll hurt me to see one cut up into a race truck, especially a rare '92 model. BTW I've never been able to find any kind of breakdown on the production numbers either.

Anyone know exactly where the instrument cluster grounds to on an '89 MJ? And Is it the Same in a '91 XJ? Instrument cluster is dead in my MJ and I think it may be a ground issue. Gas guage is wrapped around way past full and the other guages all froze in the normal operating position. Any ideas? I blew the motor in the XJ when this happened so I'd really like to get it figured out before I drive the truck anymore.

You don't mention what transmissions you're dealing with, you'll need the 4.0 trans as well. This will also require the driveshafts be changed. The front one from the XJ will work but you'll need to find one for the rear or have your current one modified. As for the fuel pump, the entire XJ sender will not fit the MJ tank but I think you should be able to swap just the pump.