Green Mesa XJ

I read the OP again, the 95 4.0 need the cam reading to spark. So the 95 distributor might fix it. If it’s anti-theft their might be away to disable it but I’d try to source a PCM that doesn’t have anti-theft. Sent from my iPhone using Tapatalk Pro

The 84 was carbureted, was it mechanical or electric fuel pump. From what I can tell it’s a mess, look like a mid 90s intake and injection system, to make the 90s engine management work he will need CPS ( in the bell housing 1995) and HO distributor (cam sensor) and fuel pressure of something like 40 lb. Carbureted systems or like 3 to 6 lb. Going to need the 1995 computer too. And maybe alternator since the computer controls it, maybe it is not really necessary don’t know. Easiest solution is grab the harness and computer from a working HO 4.0 91-95. Or aftermarket computer and harness. Simplest set up is carbureted with no computer, eliminate non essential wiring. Sent from my iPhone using Tapatalk Pro

I have a wagoneer but it was before the quad headlights so I’m not sure how they run the wires for that setup. I know some guys make their own harness with relays to help take the load off the factory set up which often melts the plug. I would think if it runs it to the headlight harness it would be for the fog lights. You may have fish out the factory fog light wiring to see what getting power. (should be a left and right side plugs/wires feeding from around the headlights.) The wiper patch is weird, I’m not sure what they were doing but it probably works only on high or something. When I first got my xj a windshield leak shorted out delay module I removed the module and plugged both sides together, wipers worked normally (no delay) for a year until I went home where I had plenty of junk yards to pick. Sent from my iPhone using Tapatalk Pro

I picked up a brand new 1990 Renix computer for $14 bucks because they thought it was a ABS computer. Maybe I’m the sucker cause I don’t own a Renix yet but I keep the parts around. Anyway that relay looks aftermarket from what I see, I’m thinking they added fog lights or fan. Only way to tell is trace it back. Sent from my iPhone using Tapatalk Pro

Even 93-95 harness might not play well together. OBDII engine is not going to play with OBDI body harness. Some of the sensors on the engine can be the same or similar but the sweeping changes made with OBDII made most of it incompatible. Judging from the XJ changes I doubt the main harness will even come close to connecting. If the block and head stay the same through the years you should be able to use whatever you can get the complete harness for, although the OBDII will probably have a few new sensors that might not have a place on the old 93 motor. Sent from my iPhone using Tapatalk Pro

I have a 91 XJ with HO 4.0 as well, blowby the where most of the oil is lost now. Newer valve cover should solve that problem. On our 91 it leaked bloody everywhere, I’ve replaced distributor with a new seal or gasket, o rings for the oil filter adapter, crankshaft seal in the timing cover, timing cover the gasket around the oil pan and timing cover, valve cover gasket, Oil pan gasket didn’t leak except by the timing cover, which I finally redid last year. Probably still have valve seal leaks , the dipstick and blowby in the air filter. Might have some slight oil seepage from the headgasket or it might be something else. Our HO XJ has 300k on it, compression is lower than what the OP posted, actually that compression on a 4.0 wouldn’t bother me. I’ve replaced the injectors several times as well. Right now that motor is not using or leaking much in the way of oil, kind of freaks me out, used to be like clock work after so many miles add so much oil. Now it steady for the first time in 16 years. Over the years I replaced all the seals mentioned but still had various leaks like rear main, bought some snake oil, a seal restore stocked at Walmart, and a few oil changes later a can of Engine Restore. The oil leaks mostly stoped by the second oil change, I know the seal restore can do some awful crap swelling the seals, but I wanted to try it and figured with 300k miles what the hell. Already have a JY motor to swap it out. Still I wouldn’t necessarily recommend it. The engine restore is snake oil that can work to restore compression, seen it proven. Bad enough problem it does nothing but is certain problems it’s effective. I don’t know if it helped out XJ or not, never bothered to test it again and it never felt any different from usual. that engine has never run weak, with 300k I know it must be tired but it never lets you feel it when driving. I don’t know it it’s worth trying to redo the rings on the pistons, for one I don’t think the compression is bad, also the way the engines worn together with the piston rings it’s probably better to leave it be unless the cylinder is going to be machined and bored out, so everything new is perfectly circular and size matched. Sent from my iPhone using Tapatalk Pro

I’m not sure what the difference between one wire set up and two, I would think the voltage regulator would need at least one line in the plug to work. the 94 amp alternator I put in my XJ says the same thing about one wire or two and I just hooked it up normally. Bottom line it’s a 12si alternator replacing a 12si, just the new one happens to be more powerful. There is another upgrade got 12si alternators where a newer GM alternator is used, that more complex, they sell kits to adapt it. But this is the same alternator going back. Sent from my iPhone using Tapatalk Pro

Gene has it exactly right. I believe the 87-90 Renix jeeps used the same alternators as 84-86 XJ/MJ. Besides the 86 2.5 is the first year of the Renix. The 12si is just a standard GM alternator. On my 85 XJ with 2.8 GM v6 (1986 engine harness) that powermaster alternator would plug right in. Your 1986 2.5 uses the same alternator as the 2.8 V6, as long as your alternator plugs exist now you should just plug it in. If those are damaged you can find a plug with pigtail to repair the two prong plug. Sent from my iPhone using Tapatalk Pro

Are you talking about the vacuum harness or the lines going to the CAD? Vacuum harness is available aftermarket that should fit 84-91 according to the description. Although I seem to remember our 91 XJ was an odd year hard to find at the dealer part. If it the lines going to the CAD some vacuum line from the parts store will do the job nicely, I can probably find a diagram or get a picture of my 85 XJs lines if you need it. Eliminating the need for the harness and plugging the line is another solution . Sent from my iPhone using Tapatalk Pro

I think there is a new cast aftermarket head that was designed to fit 7120, 0630, & 0331 head 4.0s. I’ve seen a few on eBay and Amazon, get decent reviews (so far) and are cheap. Personally I’d rather a good rebuilt 7120 Sent from my iPhone using Tapatalk Pro

X2 on the stethoscope. I’ve had a belt pulley make a intermittent horrible squeak. Did it at first only when it rained, I thought it was just the belt. Cheap Chinese bearing eventually locked up. Sent from my iPhone using Tapatalk Pro

Well there are several passage ways besides the combustion cambers/cylinders, a headgasket can leak at any of them. Some Chrysler/Jeep 3.7 & 4.7 owners have documented (meaning repaired under warranty) oil leaks from the headgasket, with no contamination of the coolant and no seal issues with the compression, just oil leaking out from the side of the block at the headgasket. In this case I still would test everything just because it’s unlikely and I have no idea what the OP actually is seeing. A none running vehicle is difficult to diagnosed Online , it may be a mechanic’s special but it can be a novices nightmare. I’ve seen so many young guys and gals get their hands on a older (their age) vehicle and jump the shark trying to fix what was a simple repair. For all we know the engine is toast and locked up. Sent from my iPhone using Tapatalk Pro

Possible but given it’s a 27 year old vehicle it could be a number of things disintegrating over time, like the rubber on the radiator cap or some form of stop leak. I don’t know how meticulous the maintenance was by previous owners, best bet is to start with compression testing as a base line, then move on to other tests. Headgaskets can go on these 4.0 but they are stout engines, they die hard. Could be you need a new gasket but I would test first. How does the oil look? Sent from my iPhone using Tapatalk Pro

Dunno looks kind of like plate they’d mount a ABS unit to. Not sure on the remix Sent from my iPhone using Tapatalk Pro

here is the link for the thread with the booster pictures, it was another WJ booster thread, lost of good advice there (Eagle, Cruiser, H0rnbrod, Rockfrog) . My pictures are at end bottom of the thread, I only looked a the 95 ZJ boosted because Rockfrog said it swapped in no problem. So I got one to compare to the 96 XJ booster, then ended up comparing all of them.

No 97 XJ is too different to work. WJ booster would work better than 97 XJ. But like I said 95-96 XJ and 95-98 ZJ are probably the best fit. I’ll see if I can find the post with a picture of the different boosters Sent from my iPhone using Tapatalk Pro

Is is a vacuum disconnect? Yeah those things can be finicky. These are jeeps can do pretty good with stock set up. Bet the hell out of my 85 XJ off road before the factory leaf springs finally broke. Went through at least three axels before that. Sent from my iPhone using Tapatalk Pro

Um, you can fabricate it to work, plenty of how to videos out there. In thread somewhere here I have pictures of the various boosters for the dual diaphragm upgrade. The 95 -96 XJ And 95-98 ZJ boosters are very similar and make for a good swap. The pre-95 ZJ booster will not work. I’m not sure which year MJ you are working with, but the plunger can be modified to work with the pre-91 jeeps pretty easily. Only other thing is the WJ boost might need some extra room the around the firewall, maybe a slight trim of a metal lip if I remember right. Oh if that WJ has the flexible brake lines those are a good get. Sent from my iPhone using Tapatalk Pro

Muriatuc acid? How did you clean/neutralize the acid? It will eat all the rust in a tank then creat more if it’s not sealed off. I may be completely wrong on this. I know it’s a old school trick, I also know muriatic acid like to eat and eat causing a worst problem in some cases. Sent from my iPhone using Tapatalk Pro

I’d try the swapping relays around to see if it’s the problem. Pressure dropping to 0 sound like it’s electrical in nature, possibly a bad pump . Did you use a bosh fuel pump? Sent from my iPhone using Tapatalk Pro

Yes. It’s also a plug usually missing on junk yard dash harness for the old XJ/MJ because it melts and people picking over the jeeps cut those plugs out if it’s any good. Sent from my iPhone using Tapatalk Pro

I knew a guy who did body work he hated replacing Cherokee doors, said the was like every day of the week production was different, every door had a lot of adjusting to get the lines correct. Sent from my iPhone using Tapatalk Pro

I have two spare ecu for our XJ when I did swap out to Test they never were the problem. These computers are usually pretty reliable even 26 years on. If you want to test it just pick up a cheap junk yard ecu, match the year and ecu number to be sure of interchange. I wouldn’t bother with rebuilt or trying to find a pricy ecu specialist, a plane old used ecu with a guaranteed to be good warranty is enough to test and use if it’s the problem. But check the codes see if anything is being flagged. Sadly wiring can be a problem, don’t know where to describe the trouble shooting for that. To me I’m thinking fuel pressure test, hard starting is normally a bad check valve in the fuel pump, one trick is to prime the pump by turning the ignition to on but not starting the engine. Do this three times you should hear the fuel pump prime. Bad fuel pump or injectors would keep it running like it’s not getting enough gas. oxygen sensor and maybe MAP sensor because every time my MAP sensor vacuum line was disconnected the jeep ran like crap can’t figure out why yours would run better with it disconnected. Even alternators can cause weird issues. These are a few ideas that may be way off for your symptoms. Sent from my iPhone using Tapatalk Pro

Wait the MAP disconnected let’s it idle correctly ? Maybe I’m missing something but that seems backwards. Sent from my iPhone using Tapatalk Pro

No. Sorry. Even if it is a AX-15 it’ll be completely wrong unless you have the skills to tear both transmissions down to swap over the housing and output to make it work with the transfer case. I believe 1989 is the split year on the transmission. Peugeot and Aisin. Also the Peugeot uses a 21 spline input for the transfer case and the AX-15 is 23 spline. at least I’m pretty sure the ax15 marked the change to 23 spline in 1990 Sent from my iPhone using Tapatalk Pro