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2.5-4.0 tj swap help

2K views 14 replies 9 participants last post by  JeeperDon 
#1 ·
im getting ready to swap out my blowen 2.5 for a 4.0 in my 99TJ, can anyone give me any help or advise? im getting the motor/trans/ecu/harness from user on another forum, i will get the t/case locally or go atlas/stak, what all will i need to change other then motor mounts? thanks
 
#4 ·
tranny mount, cooling sytem, tranny cooler if its an auto swap, linkage, exhaust, the list is VERY long on details

I suggest you sit down and do a detail list BEFORE you even start removing a nut.

And search and reading other's build threads is a good starting point. The Cherokee forumn has alot of tech, but beware, they can be brutal.
 
#8 ·
This is a very simple swap.
Radiator is the exact same so you already have it.
get the harness and ECM attached to the drivetrain. Re-Weld engine mounts, and find the wire that feeds 12v to the ECM.. plug it in.. plug the one to the switch.. and you are almost done. Do it. Don't be afraid., it is very simple to do it.
 
#12 · (Edited)
#10 ·
Do you relize you went from a OBD2 system to a OBD1!? Go buy a chilton's for a 95 YJ. There are complete wiring schematics for that setup. Or google "wiring diagram 1995 jeep wrangler"

And you might want a diagram for your TJ with the 4.0 to cross match and see whats different between the two systems.
 
#11 ·
Rather than wiring this one in, you might consider getting the intake, TB, fuel system, computer, wiring from a newer TJ. You now have a pretty major hurdle to overcome. The general rule is to swap in a newer motor, not an older one, especially not switching the OBDI/II part. You will be trying to integrate air bags into the '95 wiring and all, not good. You won't have gauges since the '99 likely has CAN bus (sort of like car-USB) and the '95 didn't. I put an '02 motor into my '93, much easier in the 'put in a newer' direction.
 
#14 ·
Depends on the state, I know when I lived in OH (late 90's), they did not have smog laws there. I know also here in FL,AL, and MS there are non of those bs laws either, but you are correct in that the states that do have them require same year or newer motor for emmissions. So he may be ok up there.
 
#15 · (Edited)
I just Googled it. The 7 main counties in OH (of 88) have 'e-check' required to register your vehicle, likely more counties in '08 it said. If any emission equip on your vehicle is tampered with, the vehicle fails, period. Since the ECM alone is clearly part of that system, it looks to me like the OP is screwed.
 
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