Topic: TBI and MPI Questions??

[4bangher]

I have a 90 and a 94 both 2.5L one is a TBI and the other is the MPI. I have a 4.3 motor with 700r4 that is going in the 94 (not the 90 due to registration complications) The long block on the 90 is brand new less than 100mi and I will have the entire drive train from the 94 collecting dust so my question is on compatibility of the two. I want to keep the 90 long block and use all the 94 peripherals (i.e. intake, exhaust, drive belt accessories and so forth only keep the 90 long block if possible) Has this been done before is it completely impossible? The only too hiccups I fore see at this point would be:
   1. Will the 94 distributor work in the 90?
   2. The Bulk head connector?
I have looked into the cam and they have same lift and durations and overlap only difference was the actual timing of the cam being a 4 deg difference can’t remember if it was adv. or ret. off the top of my head. I just had the brain storm last night so I haven’t gotten too far in my research at this point. Just fishing to see if someone else has tried this? Any constructive info would be great.

[lanulos89]

it has to be possible.  long story short i just swapped my 95 yj's 2.5l into my 98 tj.  all i had to swap over was the oil pressure switch, pickup from distributor, temp sensor.  and motor mount brackets  and it poped right in.

[Mr_Random]

I'm doing this right now with a 94 system into an 86. The bulkhead connectors, while sharing the same style plug, do not have the same pinout.

All accessories will attach exactly the same, I would use the new stuff on the older block, because it has a higher compression ratio (more power).

here's my basic setup (Frankenstein style):
86 XJ pioneer chassis
88 rebuilt engine (valve job, dished .030 oversized pistons, timing/cam/lifter set)
94/5 (can't remember) YJ engine harness and correct sensors.
2001/2 (can't remember exactly) intake/fuel rail/injectors
97 fuel tank/pump
96- 4.0TB
98 alternator/A/C/P/S brackets
94 4.0 vibration dampener (It works! and is a little heavier, will make the engine smoother I hope).
94 flywheel
88 exhaust manifold (would have used mine, but it is majorly cracked), all I have to do is block off the EGR tube.
94/5 distributor
I'll add more if I can think of anything else.
The only original parts will be the axles and transmission/t-case. Both axles have been rebuilt, and the tranny is getting rebuilt right now. Eventually I'll do an ax-15/231 swap, and grab an XJ 44 I've been eyeing.

Biggest problem right now is rewiring the bulkhead connector on the 94 engine harness. I'm pretty sure the ENGINE would work if plugged right in, but nothing else; lights, interior, etc. I'll have to make a correlation list and possibly a wiring diagram, so when I'm done I'll post what I have up here.

[4bangher]

aww man great info I am stoked if you can keep your updates posted here and I will do the same I have access to alldata if  you have any questions on the wiring I will also research it and post what I find here. I may even install a hesco cam. not sure depending on funds I get from selling the TBI Stuff.

[4bangher]

I will have to order an inertia ring for the flywheel since I will have it out at the time of the swap.

[Mr_Random]

I will have to order an inertia ring for the flywheel since I will have it out at the time of the swap.

Yeah I found a deal on an uninstalled one from a guy who did a 4.0 swap, but at the time I had to devote funds elsewhere.

What does alldata have? I have 88, 94, and 97 FSMs, plus a chilton's manual and a comanche 88 wiring manual, but I don't think I could ever have enough information, haha...

Don't go my route if you can help it, if I had a chance I would have used all 94 fuel systems, but I couldn't get ahold of the right fuel rail, so I just got a newer style tank/pump. I got a stock ZJ gas tank skid, so it actually works well.

I also couldn't find the full harness from a 2.5 XJ (or any harness for that matter), so I had to get a YJ harness. The interior harness is inadequate (no power locks, A/C, etc) for my XJ, so I am left with two options; a full harness from a JY 4.0 XJ, or splicing the new engine harness into the old bulkhead connectors. I'm going with the second because it's more convenient, cheaper, I don't have to tear into the interior, and I won't have to go searching for an XJ with the same options as mine.

Oh, and same with the cam, wanted one, but funds had to go elsewhere... sucks, but the next engine will get the good treatment.

[4bangher]

Today I got the bulk head pin outs for both jeeps the 90 and the 94 from all data. I am going outside now to compare the sheets to what I actually have. I will  then make a new sheet and post it here about 25% of the pins are the same which is going to be helpful.

[Mr_Random]

Today I got the bulk head pin outs for both jeeps the 90 and the 94 from all data. I am going outside now to compare the sheets to what I actually have. I will  then make a new sheet and post it here about 25% of the pins are the same which is going to be helpful.

Awesome! I MAY not need the info (I'm purchasing an interior harness off another jeeper just in case), but that it would be a big help anyways. All I've found (in my FSMs) is the pinout for a 97, which is of no help to me...

[4bangher]

here is what I have gathered so far.

[attachment deleted by admin]

[Mr_Random]

Looks exactly how I would have done one, but after sitting down and labeling each and every wire... thanks for the help! Ha

Okay, I can help out a little on filling in the gaps; the later harness has about ten wires that run separately into the cab, connecting to the a/c clutch, fuel guage, pressure guage, 4wd switch, CTS, and a couple other things (OBD connector too I think).

The older wiring lists a few connections as "battery," well their corresponding connectors for 94 are actually the same, just labelled differently. Notice how two say "feed," good indication of a "hot" connection to the battery. The head lamp switch on 94 may be labeled wrong itself, technically the "low beam head lamps" wire will have a switch, and the "head lamp switch" is a constant hot for both high and low beam (probably turn signal and side marker lamps too).

If you need any help just let me know, I'll try to figure it out more. I just bought an interior harness for the XJ, so I may not need to do any splicing, but it'll be good to have the info anyways!

[labyerly]

I haven't been a member long enough to get to the "for sale" section but I'm looking to buy an intake manifold for my '93 2.5l YJ.  Winter is NOT the time to go to the junk yard in North Dakota!  I figured to buy one, port/polish it and then get a TB spacer and a 4.0 TB before spring melt up here.  If anyone has the whole thing for sale, I would even entertain that.  Thanks.

[Jeffy]

Check out www.car-parts.com.

[Mr_Random]

BTT

I am really getting going on sorting out the wiring harness problems. I bought an interior harness from a 91+ 4.0 cherokee, but found out that the 94 YJ bung has more in common with the 86 bung than the 91+ cherokee one. Oh well, I helped out a fellow jeeper with the deal!

Now, I have REALLY detailed layouts for the YJ bung (other than the correlation chart 4bangher posted), but nothing for the 90- cherokee. The YJ section of the chart posted here isn't absolutely complete, I found some holes, so I'm not completely trusting the XJ section. I would appreciate if anyone can find the complete bung pinout for me please! If not I'll go outside and painstakingly isolate every wire for my personal harness (my original plan)... ha.

There is a secondary harness plug that extends through the firewall and (on the YJ at least) connects to the following; 1. A/C t-stat, 2. Fuel Gauge, 3. Coolant temp sender (gauge cluster), 4. IGN switch (hot), 5. Horn, 10. 4wd indicator, 9. Back-up lamp, 8. Oil Pressure Sender, 7. IGN (start?), and 6. A/C request (not sure what that means).

Sorry I kinda screwed that up, read it counter clockwise, not according to plug number... too lazy to re arrange...

Anyways, I will splice/extend the wires on said plug to necessary pins on the firewall bung, and figure out what I can do with ones that don't have a corresponding pin there.

phew... lots more to do!

[Bounty Hunter]

labyerly, I think I have an intake manifold for you, and a lot of other 2.5 parts.  Email me at bountyhunter AT sija.org . 

I also see a lot of mention of 4.0L TB swaps.  I often have 62mm TB's available for an even larger improvement in airflow.

Sorry for hijack.