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swapping newer 4.0

Andrew T

NAXJA Forum User
Location
Houston, TX
I have a 93 XJ, 4.0, AW4, and 231. I have new axles and a new t-case, but the engine and tranny both have about 165,000 miles, and I'm really noticing a power loss. My idea is to swap in a newer 4.0L and auto tranny from the newer body-style. Has anyone done this? What differences are there as far as the ECU is concerned? I know that mine has a distributor and the newer ones have it "built in" on the camshaft (I think), but how does this affect the swap? Basically, is there anything special I need to watch for when getting a drivetrain? I just don't want to spend $$$ then have it not work right....

Thanks in advance...

Andrew
 
165,000 miles is nothing on a 4.0L unless it was really abused. Before dumping a lot of money on a replacement engine, I'd start looking at simple things that could reduce power -- such as a clogged catalytic converter, dirty injectors, dirty fuel filter -- simple stuff that is often overlooked.
 
Assuming that the engine has been used, but not necessarily abused, simple stuff like that will make that much of a difference? I know that those thing all help, but I just don't see them doing that much. But, as you said, a newer engine swap would be a lot of $$$, so I guess it wouldn't hurt to try...

Andrew
 
If you need to replace the cat, then the O2 is most likely on its last leg. The parts listed above, as well as the O2, can produce a bit of lag that would be noticable in the time-2-rev. Builds up slower. If you want to go with the newer block, get around a '97-99 with the different ignition system. The 7120 heads on the older blocks are better and the 99 and up wj 4.0 intake manifold has a bit longer sweap on the runners and would give more umph. If you have the ABS, it would have to be removed to fit the intake. http://www.angelfire.com/my/fan/IAT_sensor.html Adjustable MAP Sensor
 
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