'96 XJ 4.0/AW4 into a '98 XJ. Motor/Trans differences? *URGENT*

Hey guys, Briefly, My 1998 XJ is getting fairly tired after 258,000 hard miles... Normally, i would just rebuild by 4.0 and keep on going... but my transmission is pretty tired too...

I have a chance to buy a 1996 4.0 drive line: 4.0 motor, AW4 transmission, and a spare np231 at a great deal, and it only has 28,000 original miles on it.

I need to make the decision fast, before the motor set is thrown on Craigslist and someone else snags it up...

Obviously, a 1996 would be OBD2 like my 1998. My main concerns are compatiabilty.

Im wondering what would be entailed in the swap... Will my ECU work with the 1996 driveline? What would be the differences between the 1996 Drive Line, and my 1998 Drive Line? Would i be looking at a straight swap, using my electronics? OR, would i be looking at rewiring a few little things? OR would i be looking at some significant work to make it work? I love my Cherokee, and have owned it for the past 10 years, and never plan on selling it, so it's definitely worth my while. However, I am about to finish up Law School, and time is limited. I would be doing the swap myself. I'm mechanically inclined, but again, time is limited.

Im trying to make a quick decision, and want to make sure I'm not making something difficult for myself getting the 1996 drive line, as opposed to holding out and looking for a 1997-1999 Drive line.

The combo I'm looking at is CLEAN, and has never been broken apart. 28,000 miles would be hard to come by in another Motor/Trans combo, so I'd really like to snag it up.

Are there any gurus out there that could give me a quick breakdown? Engine management or ECU, Gauges, AC hookups and control, Transmission control, etc... All of these are my concerns. I need the vehicle to be able to be plugged up and pass OBD2 emissions testing here in North Carolina also.

Thanks in Advance for the help!!!
-Brian

Bump

Try this thread -> Everything you wanted to know about the AW-4


Simply reuse as needed or required the original 1998 parts on your "new" engine: Intake/Exhaust manifolds, flex plate/flywheel, cylinder head, distributor-less ignition or distributor assembly, engine sensors, fan belt driven accessories and mounting brackets.

1996 vs. 98 everything should be exactly the same.

yup, maybe a few sensor connector differences but not likely.
buy it run it

Im pretty sound that the motor would work now obviously.. but I just told the guy that id pass... The transmission compatibility is just too questionable to worth the risk.. I told him if he decided to separate, id snag that motor up in a heartbeat, and just try to source a transmission elsewhere...

The '96-'98 share the same motor, the S model. I'm looking to replace my '96 motor that stopped running at 499,965 miles on it.

Should the ecm be replaced? I put a 96 motor in my 98. Replaced plugs, wires, cap, rotor, pick-up coil, crankshaft position sensor, o2 sensors, and cat. It was done professionally. It hardly starts, when it does it almost dies. After it gets going, it backfires rapidly at 2000 rpms and dies. I am almost out of options i reckon. Everyone I ask said the ecm ought to be replaced. Advice?

HunterRivett said:

Should the ecm be replaced? I put a 96 motor in my 98. Replaced plugs, wires, cap, rotor, pick-up coil, crankshaft position sensor, o2 sensors, and cat. It was done professionally. It hardly starts, when it does it almost dies. After it gets going, it backfires rapidly at 2000 rpms and dies. I am almost out of options i reckon. Everyone I ask said the ecm ought to be replaced. Advice?

Click to expand...

What diagnostics and/or testing shows the ECM to be faulty ? What does your professional mechanic say about the problem ? Why can't he fix it ?

HunterRivett said:

Should the ecm be replaced? I put a 96 motor in my 98. Replaced plugs, wires, cap, rotor, pick-up coil, crankshaft position sensor, o2 sensors, and cat. It was done professionally. It hardly starts, when it does it almost dies. After it gets going, it backfires rapidly at 2000 rpms and dies. I am almost out of options i reckon. Everyone I ask said the ecm ought to be replaced. Advice?

Click to expand...

Sounds like the distributor is off a tooth.