89MJ4spdman2wd Posted June 14, 2015 Posted June 14, 2015 MPI and TBI are completely different. I just done this swap with a 91 YJ MPI into my TBI and lets just say it can get very very touchy. The Big plug on the firewall doesnt match most of the wires so you have to pull the metal tabs out without destroying them and move them so they line up in the right spot so the fuse panel and interior equipment will work. ALso the MPI has so many extra wires you can cut out. Can be very tedious but i love it now plus the my MPG is better. If someone does this i can give a few pointers on it because there are no writeups i could find for it. Good luck selling this is a worthwhile swap for those 4 banger lovers like me. Cole Hello Gavin here I am trying to rewire a 93 2.5 mpfi with all the harness down to battery clamps in to a 89 comanche 2.5 tbi the engine is in not sure about the fuel pump issues? What kind of pump do I need to put in? Do I need to change my tank? any help would be Happily taken thanks
Crash Posted June 14, 2015 Posted June 14, 2015 I think the 4.0L pump will work, as far as I know the earlier 2.5 pump doesn't have enough output.
mnkyboy Posted June 14, 2015 Posted June 14, 2015 I used a 91 2.5l mpi pump and sender in my 89 tank.
89MJ4spdman2wd Posted June 15, 2015 Author Posted June 15, 2015 Gavin here again Also any other information on the Vacuum lines Mostly any information on rewiring the new harness into the old or is it vice-versa I do believe it won't be hard but a time and patience job And Help From Good People Thanks again all out there helping this Newbie
mnkyboy Posted June 16, 2015 Posted June 16, 2015 http://comancheclub.com/topic/18588-xj-dash-harness-to-rear-mj-harness-wiring-guides/
89MJ4spdman2wd Posted June 21, 2015 Author Posted June 21, 2015 I did look at the charts But what if one does not have the donor plugs for under the dash. Should i try to get one? Also how or what do i need under the hood for the plug that goes into the fuse box i sort of understand the pulling of pins and moving them any help would be nice i look under the hood and am just over whelmed
mnkyboy Posted June 21, 2015 Posted June 21, 2015 Do you have a donor harness? You should be able to swap in an XJ or MJ MPI harness then wire it to the rear harness with the info in the link i posted and be good to go. I have 91 MJ engine and dash harnesses spliced into my 89 rear harness running 95 YJ engine management on my 89 block and head.
89MJ4spdman2wd Posted June 21, 2015 Author Posted June 21, 2015 I have the computer the fuse box and battery clamps under the hood i have nothing for in the cab the write up shows for under the dash correct nothing about under the hood rear harness is where also what does HO era mean also the Renix era confuses me TBI Renix MPFI non-Renix ?? Sorry for all the questions posting picture ...How
mnkyboy Posted June 21, 2015 Posted June 21, 2015 Renix is what you have,HO is basically what your swapping in. The write up is for 4.0l swaps but the info is the same. What engine harness do you have? What is it out of?
89MJ4spdman2wd Posted June 21, 2015 Author Posted June 21, 2015 The harness was attached to the engine I was told it came out of a 93 Cherokee Rwd with only 38000 km on it the 5 speed transmission was attached as well
mnkyboy Posted June 21, 2015 Posted June 21, 2015 So your trying to hook the engine harness to the connector on the firewall,your going to need the pin outs for your truck and the XJ harness then you can see what pins needs moved. When i did mine i took the entire engine and under dash harness from the donor rig then all i had to do was tie it into the rear harness connectors which are in the driver side kick panel.
89MJ4spdman2wd Posted June 21, 2015 Author Posted June 21, 2015 I wish it was all there. Sounds easier to rig up So the XJ harness is the one for under the dash as in the black and grey one or the big one under the hood How can I post pictures
mnkyboy Posted June 21, 2015 Posted June 21, 2015 You have too host the pics somewhere,i use photobucket. Once you do that you can post the img code here and the pic will display.
89MJ4spdman2wd Posted June 24, 2015 Author Posted June 24, 2015 so would I be able to go and get any 93 mpfi under dash harness and do what your diagrams say basically plug the 93 main harness into the wall under the hood and re wire under the dash and then just get rid of old 89 tbi harness
mnkyboy Posted June 24, 2015 Posted June 24, 2015 91-93 MJ or XJ should work,the dash harness changed a little in 94. The dash harness will go from the firewall plug to the rear harness plug in the kick panel,if you get the dash harness that matches your engine harness you should be able to splice in the rear harness and everything should work. My 91 harness plugged right into the column and everything else under the dash.
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