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97 XJ 4.0 into a 83 CJ Questions

2K views 12 replies 5 participants last post by  Rokmycj 
#1 ·
OK hoping to join the "elite" goup of people that have been able to splice in an OBD-II harness AND get it to work (re: 4.0 swap/Spark Probs :flipoff2: )

OK, Here's my questions:
#1 Am I screwed? I got a 97 engine and harness, but the ECM is from a 96.

#2 Can a check engine light be wired in, since it's controlled by the CCD bus? It looks like I have to cannibalize a CCD dash ? TJ fuel sending unit :flipoff2:

#3 Speed sensor, will the one from Hesco work with this harness, since it's designed for the OBD-I MPI kit ?

Thanks
Tony
 
#2 ·
I'm sorry, but I don't know about the wiring, but what are you going to do about the fuel system.

To through another monkey wrench in your plan the '97 should have an in-tank fuel regulator. The 91-95's are on the fuel rail. I have yet to see a new fuel system work in a YJ or CJ. If you have found away around this problem please post it. The people I know who have done this swap have pulled a harness, sensors and fuel system off a 91-95 to get it to work.
 
#3 ·
wiring:
afaik, the MIL lamp is the same as in the pre obdII models. you provide 12 v, and the computer provides ground when something goes wrong. 96 or 97 ecm shouldn't matter. AS LONG AS THEY ARE BOTH FROM 4.0L's!! if you have a 2.5L computer, your engine will only run on the #4 cyl.
don't ask how I know that.

you can use the TJ sending unit, but oyu need a custom tank. back in the day, you'd just get one from Trailquest, but they're prices have gone up over $400 in the past several years. you can also just slap on the pre-obdII fuel rail with the regulator and the return line.

the speed sensor I think you're screwd on. obdII's use 8v sensors, obdI's use 5v sensors. you may have to modify a stock sensor, or gut a Hesco one and replace the internals.
 
#5 ·
DE Jeeper said:
I'm sorry, but I don't know about the wiring, but what are you going to do about the fuel system.

To through another monkey wrench in your plan the '97 should have an in-tank fuel regulator. The 91-95's are on the fuel rail. I have yet to see a new fuel system work in a YJ or CJ. If you have found away around this problem please post it. The people I know who have done this swap have pulled a harness, sensors and fuel system off a 91-95 to get it to work.
My thoughts on the fuel system was to use an external regulator
like the one offered by Hesco

Tony W
 
#6 ·
That is a nice unit, but it should be at $325. Good luck with the electronics and don't forget you need a provision for the CPS. Hesco has that for about $450. For the price of those two parts alone I was able to do a 4.0l and AX-15 swap with the '91 motor. Again good luck.
 
#7 ·
DE Jeeper said:
That is a nice unit, but it should be at $325. Good luck with the electronics and don't forget you need a provision for the CPS. Hesco has that for about $450. For the price of those two parts alone I was able to do a 4.0l and AX-15 swap with the '91 motor. Again good luck.
Oh, I didn't say I was going to buy that unit from them. I can build one like it for around $200. I agree $325 is a bit steep.

I have the CPS figured out, got an AX-15 (thanks Doc Johnson)

Tony W
 
#8 ·
I'll throw my $.02 worth in, as I'm doing the same thing with a '96 XJ 4.0L and AX-15 into my '85 CJ-7. The fuel system I put together from parts from Summit. I used a Mallory fuel filter, then a Mallory fuel pump that puts out 50psi, to a Mallory adjustable fuel pressure regulator. It turns over and it's getting plenty of fuel (adjusted down to 42-49psi), but the wiring is not done, so it hasn't ran yet.

And Sundowner just threw a monkey into my wrench with the VSS. I bought one from Hesco assuming that it would work. How can I modify it to provide 8v? Any suggestions? I have about 5 more wires to splice, and I wasn't expecting to have that problem.

Sundowner, by the way, Semper Fi.
 
#9 ·
here's a trick around the CPS costs I posted on JU a long time ago

for future reference, the slick trick is to buy the HESCO CPS sensor bracket from jeepconnection.com, use it with a sensor from an auto 6 cyl, and buy the Hesco damper wheel from somewhere like 4wdhardware, copy the holes onto your stock damper with a drill press, and send the Hesco damper back for a refund (you guys at 4wdh reading this?) :)
I'm not 100% certain on the VSS function. were I you, I'd plug it in and drive around. if te VSS doesn't jive with the computer, the computer will give you a MIL flag after about 20 minutes of operation (cLosed loop changeover+ about 15 min)
If it doesn't work, we'll figure out another soloution.
 
#10 · (Edited)
Medic said:
I'll throw my $.02 worth in, as I'm doing the same thing with a '96 XJ 4.0L and AX-15 into my '85 CJ-7. The fuel system I put together from parts from Summit. I used a Mallory fuel filter, then a Mallory fuel pump that puts out 50psi, to a Mallory adjustable fuel pressure regulator. It turns over and it's getting plenty of fuel (adjusted down to 42-49psi), but the wiring is not done, so it hasn't ran yet.

And Sundowner just threw a monkey into my wrench with the VSS. I bought one from Hesco assuming that it would work. How can I modify it to provide 8v? Any suggestions? I have about 5 more wires to splice, and I wasn't expecting to have that problem.

Sundowner, by the way, Semper Fi.
About the VSS: The one Hesco sells is just an OEM replacement for a 91 Ram truck. when I called the parts store they were only $25 (vs. $79 from He$co :flipoff2: )

Any ideas on the VSS yet ? (I checked my factory manual, and it has a 5V supply so if the harness pulgs into it it might work :confused:)

I still need to get my fuel delivery straightened out. What were the P/N's from summit ?

btw: Where did you mount your ECM ?

Thanks
Tony W
 
#11 ·
ECM is dipped in rubber, mount it on the firewall under the brake booster.
I have an extra pre-96 fuel rail you can have for cheap.

Go for the VSS from the RAM, I didn't know that application, I'll store it for future use on how to screw Hesco out of cash.
 
#12 ·
I mounted the ECM the same place as Sundowner, I siliconed mine instead of wrapping it in a jimmy.
The part #'s from Summit are all from Mallory
Fuel filter: maa-3160
Fuel pump: maa-4060FI
Pressure regulator: maa-4309
I haven't checked on whether or not the VSS is going to work yet, the exhaust is hopefully going on this week or next, I'll post here if I learn anything.
 
#13 ·
There was a better solution than the Hesco kit when I put the 4.0 in my cj. I went to Parts Mike ( partsmikeparts.com ) and he machined the bell housing to take the CPS in the stock location. I think it cost around $70 plus core. I have been running the motor for two seasons now and haven't had a problem, This is a much cheaper solution, and uses stock off the shelf parts.

Joe
 
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