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96? XJ 4.0 into 1990 YJ

1528 Views 2 Replies 3 Participants Last post by  Knoxville
OK, first off, I have searched (or atleast tried. kept coming up page unavailable or some crap). I have also read some articles online, including http://www.off-road.com/jeep/tech/4lswap/index.html. Nothing seems to help me on my dilemma. So here goes.

I have a 1990 YJ w/ 4 banger, ax-5, 231, stock axles with 4.88 and 33's. I am getting (for free-ish) a 4.0, ax-15, 231 combo out of a 1996 XJ. At least I am told it is a 1996, I will check the block numbers when it arrives.

I know that there are OBD I and OBD II, and I have no idea what I have or what I am getting. So there is question 1. Do I have OBD I, and am I getting and OBD I or II.

I am going to pull the entire front end sheetmetal and pull the whole pig all at once. Then pull what I need to (motor, tranny, t-case).
Question 2: What do I need to leave in for wiring. The motor has most all of the wiring, minus computer (I know I have to get that, but waiting to see what year model it is out of.)

Am I going to have problems with fuel delivery with my current TBI fuel pump?
If so, what do I need to do.

I just had a new radiator put in, but will I have overheating problems with it? It is supposed to be a "heavy-duty" radiator. Do not know for sure.

Does anyone make a bolt in engine mount kit that bolts directly to my current mounts?

I know that I have to have new DS's made, no big deal. May just have mine retubed. I will also be upgrading to SYE, ford 8.8, body lift, and "tummy tuck" (For lack of better words. I know that is not necassarily needed, but thought I would give you enough info on how I plan on the build of the Jeep.)

Give me your thoughts, and sorry for the repost. I am sure this has been done thousands of times, and asked just as many, but I could not find anything on this with my searching that I have done.

Thanks again everybody. If you find any links that would be of help, or feel this should be in "newb", let me know.

Again, thanks.
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I did a near Identical swap a few years ago into my 90 YJ. I however had a 4.2 previously which meant the motor mounts were identical. I dont know how the 4 bangers are. I assume they'd be the same but can't say for sure. I'm pretty sure 96 was the first year for OBDII, and mine was 94 and therefore OBDI. Everything was real easy except for the wiring. I recommend you leave as much wiring in tact until you get the new motor in with all of it's wiring. Then go through and mark everything and begin swapping wires where needed. Basically just splice in the new wiring forward of the firewall into the bulkhead connector. It's a time consuming process but with patience is possible. http://www.cjoffroad.com/forums/forum.asp?FORUM_ID=24 that site was a lot of help as it's a forum all about 4.0 swaps. It's for CJs mostly but much of the info is the same. Probably the most important info you'll need is in a Service Manual you get at the dealership. They're like $100 but have all the wiring diagrams you need. Much better than Haynes or Chiltons will be. As far as engine swaps go this is one of the easier because of the lack of fab, but the wiring will be painful. Just take your time and it wont be too bad.

Because your current motor is fuel injected it should have an electric pump, and therefore you should just have to wire it in. But I could be wrong about this. Mine was a carbed 6 cyl so it had a mechanical pump and I had to add an electric pump, but I'm not positive on the 4cyls.
Radiators between 6 and 4 cyls are the same aftermarket. I had a 4 cyl TJ and ordered a new radiator for it and asked for the 6 cyl one instead for more cooling, but radiator place told me they were the same part #.
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'98 XJ 4.0L into '89 YJ (was 2.5L).. my write-up should have everything you need.
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