I have a 1999 low mileage cherokee donor viehicle that I am swapping the motor and driveline into a rust free 1998 Cherokee. Both 4.0L engines. The 1999 motor has different fuel injectors so the connector plugs from the 1998 won't plug into the injectors. The 1999 harness obviously will plug in.
The question is... can I just use the 1999 harness with the 1998 computer? I checked the pins from the harness plugs to the computer leads and they match. The only other difference is the plug going to the plug on the oil filter mount has 3 wires instead of 2. The computer has 3 ports for the wire harnesses. I'd like to leave the back plug in since the majority of those wires go into the passenger compartment.
Thanks

 

I am swapping a new motor into a '98 as we speak! To date I have had a myriad of problems getting the correct replacement engine. I tried a 99 as a donor, but there are some differences depending on the date of manufacture apparently and you probably would need to swap out your intake, oil filter mount etc so that everything mates up with your wiring harness. Theoretically you could use almost any modern 4.0 with your computer if it was stripped down to a "long block", but you might need to maintain your intake, sensors, etc to make your computer happy. As you look you should be able to see what needs to be done.

My swap has been a comedy of errors. I bought a used 99 with 27k miles on it that supposedly was inside the whole time. Pulled my engine out and went to swap intakes...the supposedly low mileage engine actually had water sitting in the head! The valves were rusted shut and I couldn't even turn the crank with a big old cheater bar. When I talked to the guy again it "may have been sitting out side a couple years"!

So I ordered a new ATK and after waiting a week I find out that even though its supposedly for a 98 and it won't work . There are differences in how the oil filter is routed, mine points towards the rear of the vehicle, the new motor points straight to the side so it wouldn't clear the suspension! I can't use it and this is the SECOND engine I've gotten. So right now my jeep is sitting with not one, not two, but THREE uesless engines on the floor next to it! I literally was on the phone ordering a new Jasper as I was writing this. Supposedly there is one in town that I can get today so that I can finally get an engine back in tomorrow. ray:

I wish you luck, but be sure that the engine you are getting isn't in worse shape than the one you have in now! Check the compression before you ever pull it out. Pull the pan and look for metal, pull the intake and be sure tha vavles look OK. Did I mention Check the compression before you do anything?

I sure hope your's is smoother than mine was...did I mention having to torch one of the insanely stupid external torx head bolts out of the bellhousing? Why in God's name anyone would use that kind of bolt in that inaccessible location is beyond comprehension...Torchs are fun and all, but not in your engine compartment!

 

I have two 1999's and one 1998. Both oil filters point to the back and clear the suspension. Remember, I bought the whole 1999 so I have the wiring harness and everything else. I just stopped by the Chrysler Dealer and we brainstormed my situation. We figured I can try firing it on the 1999 wiring harness that controls the engine functions. I will leave the 1998 computer and wiring harness in that goes to the passenger compartment. The Tech said it shouldn't hurt the computer to start it like this. According to the Tech the worst thing that can happen is to throw a code or trigger an idiot light.
My 1999 engine is in great shape... Already checked it...
Thanks for the reply.

 

Sounds like you are in good shape then! Everything should mate up for you, I'll keep my fingers crossed.

My new Jasper engine should be waiting for me in the morning. Hopefully I'll be doing a break-in by this time tomorrow!

Just in case anybody is reading this who is looking at reman engines, a word of advice: The ATK that showed up not only was not the correct engine, but was a p!ss poor example of a rebuild. They slapped it together, didn't put a pan on it, never ran oil through it, didn't put a pick-up on the pump and used cheap gaskets. I am glad it turned out to be the wrong one cause I wouldn't have trusted it. (I've heard they outsource their assembly to Mexico now...I'm just sayin')

The Jasper engines are not only compression tested, but they are supposed to be spun up on a test stand to be sure that everything will work as it should and oil is pushed through the whole thing. I feel WAY better about this new one.

Good Luck,
Parker

 

Thanks Parker and good luck to you too. I will post my results in a week or so. I got lucky today when my Sons friends Father gave me a 1997 Grand Cherokee rear end. So I'm going to pull the disc brakes off it and put them on my 1998. I'll have to post some new pictures in my profile. I have the TNT frame stiffeners and the Intense Offroad stiffeners and steering brace reinforcements welded on. Also painted the entire underbody. Going to be a nice 44,000 mile new Jeep when I'm done!
Now have to choose a lift kit!
Thanks
Mike

 

It lives again! Finished installing the new Jasper yesterday and fired it up. Easiest start I've ever done on a new motor. Cranked a couple of times, worked the TB and it started stumbling then caught! No shakes, shimmies or stumbles. I've put 50 or 60 miles on not trouble (fingers crossed)

I ended up going with a "performance" motor with a better cam and I used the new style intake with the longer runners. It should give me a decent increase in HP and more importantly torque. Can't tell much yet as I have been taking it easy, but this motor is TIGHT, you can just tell when it starts up that it will take a bit to work in, but that's good. I pull a boat so the extra will be appreciated.

Nice score on the discs, that's one that I really want to do as well. Maybe this summer if I can find a cheap rear-end...wait that didn't sound right! Cheap axle!

 

have you had any problems with this? i have a 97 cherokee that im looking to put a 99 motor and computer in. is there anything else i need to look for while doing this?

 

i swapped a 94 to a 98...you need to pretty much swap Everything over from the old motor, sensors, intake, distrubator, yata yata to make it work, idk about a 99 to 97

 

got any info on it. i also have a 90 model motor and was told it could be done at all.

 

According to my research and conversion, you can use the 99 computer with the 99 engine in the 97 if you use the front 2 (in car position) wire harnesses that go to the computer off the 99. Do you have the 99 front two wire harnesses?
You will be able to just plug the third wire harness into the 99 computer. (That's the wire harness that mostly feeds into your passenger compartment).
Where I ran into an issue is some of the functions on my overhead computer console would not work (Cherokee Classic Option) unless I used the 1998 computer.
However, when I used the 98 computer the oil pressure gauge would not work but... all the functions on the overhead computer worked. The reason is the 99 oil pressure sending unit has 3 wires and the 97 has 2 wires. I wanted to use all the 99 components since they only had 44,000 miles on them, I decided to get a mechanical oil pressure gauge and leave the 98 computer in so the overhead computer worked.
Problem solved.
Other than that I noticed the gas gauge isn't as accurate when I get under 1/4 tank with the 98 computer. I checked the amount of fuel I added with the 98 computer and the amount of fuel I added when I ran the 99 computer. The 99 computer was more accurate... I just fill her up when I get to 1/4 tank with the 98 computer and all is well.
Other than those two minor issues there were absolutely no performance differences between running the 98 or 99 computer.
The nice thing about using the 99 wire harness is it obviously plugs right into the fuel injectors on the higher performance 99 intake manifold. You got that off the 99 didn't you?
If you got the 99 starter also, I'd use that and the 99 harness will hook right up. The 97 starters had different hook ups than the 99's. Not hard to get around if you have to use the 97 starter though.
That's all I remember, but I'm sure I left something out. Post again if you have any other issues and I'm sure I'll remember how I got around them.
Mike

 

i have the whole 99 model vehicle it has been totaled i also have a rolled over o6 rubicon and plan on using one of the 2 engines.

 

From some season I cant send you a PM, but anyways, I have a 97 cherokee with a junk motor, but I also have a 95 grand cherokee 4.0L with a good motor. So basicly what you did was strip the donor motor down to a long block and swap over all the parts and it was good to go?

 

Hey guys, I swapped in a 98 intake and engine harness on my 97 Cherokee.
I don't have power to the reverse lights now. I've checked the reverse switch on the 5 speed transmission and no power there. I noticed there's an extra wire on the big wire connector from the 98 wire harness behind the distributor. I wonder if that has something to do with it? Maybe that cause the oil sender uses 3 wire on the 98 and the 97 uses 2.
I believe my problem lies in that connector but I'm hoping someone has experience with this swap before I start cutting or adding new wires to get the reverse lights working?

 

If you put a 99 in a 98 and the injector connectors are different don't swap the whole harness. Just put injectors from 98 into the 99. Same as the oil pressure sender. No need to swap the whole harness if the connector is different. Just install the correct sensor. No need to go swapping harnesses or computers. And as for the motors with the oil filters sticking straight out instead of to the rear, it's because the oil filter adapter goes on first and it's what makes the filter point to the rear. Really surprised the guy at the dealership didn't know that.

 

An 06 4.0 will not have the bosses tapped for XJ motor mounts

This^

I was thinking same, why swap all this other stuff. Maybe TL;DR and I missed it.

I will be swapping a 98 ZJ block into an 01 XJ. Swapping accs, coil pack, cam sensor; otherwise all stays same.