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2.5 to 4.0 swap in my 93 yj

7K views 8 replies 6 participants last post by  92jeep2540 
#1 ·
I have a 93 yj that has a 2.5 and ax 5 swapping in 4.0 and ax15 from cherokee that ran in the cherokee took the 2.5 yj harness spliced in injector 5 and 6 wiring in the 2.5 harness going to the bulkhead of the pcm for a 95 xj the motor was out of a 91 and the trans was out of the 95 could not get that motor to start and run correctly sounded like it lopes when trying to run. took motor out of another 95 that ran and ran good just to see if it was the motor. took right out of the cherokee and put in yj. this motor starts when it wants to but when it starts it acts like its throwing exhuasst out the throttle body. tried another computer from a 91 and it did the same thing what could be the issu???? i have spark fuel and compression but doesnt want to start any ideas im lost and not sure were else to go. thanks!!!!!!
 
#2 ·
The splicing injectors in has me worried. Your 2.5 ran fine, the 4.0 ran fine. You spliced the injectors in and now it dont run fine. Sounds like some type of incompatibility. I know the 93 I have does not have adjustable timing. The 90 does, 95 does not. Im thinking it has something to do with the different years of engine and harness. Maybe its looking for a sensor that it cant find, or something to that fact.
 
#4 ·
I'm very interested in your swap - I've got all the parts for a 2.5L to 4.0L swap, and will be doing it sometime next year. Computer issues/problems is the one thing that I'm afraid of - I'm sorry to hear about your problems.

A quick question...How did you clock the transfer case? The XJ AX15 clocks the NP231 much lower than the stock YJ.
 
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