Hi all.

I have an 87 4.0 6 cylinder 4x4 Jeep with a rod in its side wall and i have a 94 2 wheel drive jeep with a good engine. I want to put good engine in the 87 both are fuel injected. Does the ECM from the 94 need to stay with the engine? What else do I need to know before attempting this?

Thanks.

you need All the wiring and controls from the 92. I thing it would be earier to switch the front diff,tranny and tnsfer case to the 2 wd body. pretty much it is a direct bolt up you may have to cut a hole for the 4wd shifter but that is it. I never converted either way so im not really sure. It just seems to me than having to deal with rewiring and such it would be much simpler to move the 4wd parts to the other body. and if it is a matter of the body being in bad shape on the 2wd maybe you can switch body parts around.

Are the long blocks that different? I can't swap all the gear over to the newer engine from the older one?

Perhaps there is a small difference but anything you wish to swap should jump right in there. There may be an internal head or manifold difference but it should work.
Big Jim <img src="/forums/images/graemlins/pfft.gif" alt="" />

the problem is the emissions. When you switch the newer engine into your older jeep and try running it with the old computer it will not run as it should. You have the o2 sensor,coolant temp sensor and many more sensors sending info to the computer so it can adjust how much fuel it need and so on. if you run the old computer it may give the wrong info to the engine which may cause poor fuel milage,and other problems.
Another problem is if the older connectors will even hook up to the newer connectors. they change things to make them work better or to fix old problems. that is why you should switch the entire wiring harness and computer.

If you switch the front end it will be a direct bolt in.The 2 wheel drive front has all the springs and such in the exact same place as the 4 wheel drive. the trans and transfer case will bolt straight in as well. I am willing to bet you could switch the entire running gear (front diff,trans,transfer case,rear diff and driveshafts) quicker than you can switch out the engine and wiring.

Hey curevo What is to stop him from just swapping the long block.. Using all of his old computer stuff?
Big Jim <img src="/forums/images/graemlins/pfft.gif" alt="" />

That's what I'm wondering. I'm planning on putting all the 87 FI, intake, exhaust and other stuff onto the 94 long block. I just need to know if it would work. I know there can be unseen differences, like on Saturns: The 91 and 92 Saturn engines cannot be swapped into a later car or later engine swapped into an 91 or 92 Saturn simply because the crank reluctor ring is different. Any such differences here?

the intakes are different, i don't een think that the holes will line up.not to mention i beleave the poerts are different as well. they changed the head design in the early 90's i think it was 91. there is always the problem of the bolts possibly breaking in the head. at least the bolts on the drivetrain are a ton easier to replace if they break

Cuervo I don't know about the ports and manifolds being different... But I do know the gasket will be different if that is so. So looking at the gasket at the local parts house will tell if they won't fit.
Big JIm <img src="/forums/images/graemlins/pfft.gif" alt="" />

Hi there guys, new here.

I was going to ask a similar question to the one that started this thread. I have a '90 and a '91... they are way different. '91 is the first year, I think, that they made the high output motor. Which mine is. I bought it to do the swap thinking they would be the same, but my '90 is a mess under the hood compared to the '91. Looks like a pain... any ideas?