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should I re-wire everything?

Shorty

Shorty

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NAXJA Memorial Lifetime Member
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on the beach in Ocean View, VA
I'm contemplating surgery on a couple toys I've had sitting around. I would like to remove the 4.0l/ AW4/ NP231 from a currently untitled '91 4 door and install them into a 2.5l/ 5speed/ 2WD '96 2 door.

The "down and dirty" of the question is: are the wiring harnesses and engine control systems close enough to re-use the existing harness, or am I "dollars-to-doughnuts" better off rewiring it to a 1991 and using the older harness?

Both vehicles are fully operational (everything functions) so I'm not really trying to "fix" or upgrade anything, I'm just looking to consolidate my stock of "yard ornaments" and make the better of the two into one.

I'm off to work, but will check in again this evening to clarify anything needed--- thanx in advance for any input:wave:
 
You can make it work, might take two tries. Swap in 96 sensors and injectors and whatnot, and if it doesn't work then swap back to the 91 parts and ECM. Changing the harness would really suck so it would be worth trying the 96 parts first.
 
that's where I'm stuck right now-- I know the TCU from '91 has a different plug than the '96 and the stick vehicle (obviously) doesn't have one at all.

My plan for today (assuming I'm not too busy at work) is to decipher how many of the sensors are common to both (91 and 96 4.0l) and see if an ECU and TCU from the bone yard will make things any easier.

I completely agree that re-wiring everything to a '91 will be a PITA, but if it's to "smarter way" to do it, I'm not skeered to make it happen. I just don't want to find out half-way through that I coulda done it some easier way!!
 
You should have a TCU harness in the 96 even if there isn't actually a TCU. Also the TCU itself should only be $25 on ebay.

The sensors/injectors/* are going to be different but the basic operation remained the same. Installing the end pieces should work.
 
You sure don't like to do things the easy way!

Changing from OBDII 4 cylinder stick to an OBDI 6 cylinder auto.

You can do it, but you will be better off removing the entire harness from the 91, and all of the electronics, the fuel pump and sender, and I think you may need the instrument cluster too, as the resistance of the fuel gauge sending unit was reversed somewhere along the way.

Unless you are damn good with electrical, just switch everything over.
 
Does VA do emission inspection? Normally, you can go forward, not back. If the car is a '96, you'll need to use the '96 computers and sensors, and like Mr Hall suggested, a TCU, from at least a '96. The '96 won't have the fuel regulator and return line the '91 probably has.
 
joe_peters said:
You sure don't like to do things the easy way!

Changing from OBDII 4 cylinder stick to an OBDI 6 cylinder auto.

You can do it, but you will be better off removing the entire harness from the 91, and all of the electronics, the fuel pump and sender, and I think you may need the instrument cluster too, as the resistance of the fuel gauge sending unit was reversed somewhere along the way.

Unless you are damn good with electrical, just switch everything over.
Click to expand...

yup, that's me-- glutton for punishment! I tend to agree that a complete swap is probably the easy way-- just wanted to be sure I wasn't "over thinking" it.
 
heyhar said:
Does VA do emission inspection? Normally, you can go forward, not back. If the car is a '96, you'll need to use the '96 computers and sensors, and like Mr Hall suggested, a TCU, from at least a '96. The '96 won't have the fuel regulator and return line the '91 probably has.
Click to expand...

no emissions testing and little chance of failing a visual inspection as most don't know what they're looking for anywho-- more like a "if it's there, it's gotta work" inspection (friends in low places being what they are)

This thing will probably spend it's remaining days as my DD and the rented mule that I'll teach my daughter to drive in. It certainly isn't going to be used to defraud anyone or get sold to an unsuspecting buyer.
 
I thought VA required an inspection when titling, so this might cause problems if you ever wanted to sell the 96. Honestly instead of trying to cobble two running vehicles into one, why not just sell both and buy a newer 4l, 4wd XJ?
 
"cobble?" your faith in my ability seems to be lacking:bawl:

VA requires a safety inspection annually, but no emissions testing (with the exception of D.C. area and parts of Richmond)
 
Shorty said:
"cobble?" your faith in my ability seems to be lacking:bawl:

VA requires a safety inspection annually, but no emissions testing (with the exception of D.C. area and parts of Richmond)
Click to expand...

Not a doubt in your abilities, just wondering why you'd spend so much effort. Or maybe I'm just jealous that you have that much free time. Personally, I'd part out or sell the 96 and use the money to spruce up the 91.
 
lawsoncl said:
I thought VA required an inspection when titling, so this might cause problems if you ever wanted to sell the 96. Honestly instead of trying to cobble two running vehicles into one, why not just sell both and buy a newer 4l, 4wd XJ?
Click to expand...

Where would be the fun in that?

OP stands to learn more about his XJ than most Jeep dealership technicians will ever know.

I say go for it!
 
long story-- '91 was a gift that was supposed to have a clean title (operative word being supposed to) I put it together from this:

IMG00002.jpg


to this:

003-9.jpg


with spare parts (read $40.00 in paint only) and was then informed that the "clean" titls was still in "a friend of a friend of a friend's" name and he's in jail somewhere in S.C.:flamemad:

The '96 was a $500.00 cheapie that needs a cyl. head and a clutch. I'm just stubborn and refuse to have wasted my time for nothing. I enjoy the work (really) and will look at it as the next basket case rebuild in a long list of "you bought that P.O.S.?" vehicles.

I'm still in the planning stage, as I have no real need for another vehicle, but one in the lot looks better than two.
 
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