Hey guys, thanks for letting me on the forum to post. I'm looking for help with issues on the 42re in a 2001 WJ 4.0L 4x4 that I picked up as a project and have just started working on it, it was cheap due to some minor interior electrical issues and the transmission had a weird fault. The original trans would be a little noisy on startup, shift okayish while cold but once the temperature got to rising it would stop working without throwing any codes. Sometimes I could get it to move with high revs but that's a quick way to kill the engine and decided to swap it out, found a used that worked decently before my friend pulled it so I put that in. Now I'm having issues with up-shifting, occasionally kicks itself completely out of gear at highway speeds and isn't throwing any codes.

I also have an intermittent P0300 that has popped up with code for misfire on cylinders 3-6 and a slight oil leak from the valve cover that I had to clean up, has new injectors and coils from before I got it.

I have changed the entire intake valve (sensors and all) assembly, gone over every wire and even changed the trans filter twice. Fluid level is okay, no overheating and only had a P1756 show up once (after the swap) because I was short 1L of fluid. No leaks that I can find either, adjusted the annoying TV/kickdown cable several times thinking that was part of it and also swapped the output sensor on the rear of the trans twice. I do have new governor sensor and solenoid that I plan on swapping out but would like to know if you guys have any recommendations or ideas on what may be causing the issues before I start pulling things apart again.

 

I'm not sure on the WJ, but I think there is a separate transmission computer, like there is on the XJs. That might be worth looking into.

 

It depends on which setup you have, the 4.0 GC with the 42RE doesn't have a separate TCM while the larger engine (4.7L I believe) with the 45RFE and 545RFE transmissions do. Sadly I can't use either transmission on the 4.0, the codes come out the same but it can confuse some of the simpler scan tools as I found with my buddies el cheapo wifi unit. Now that my MK808 is here I can do a little bit more.

I have swapped the governor solenoid and sensor as of today, also have a new output sensor that arrived as a gift from a friend so I'll change that as well. I even installed a drain plug in the pan in hopes that now that's in for easier drainage the trans will stop acting up. That said I did have a rolling in park incident before I put it up to drain things, I found that when its in park the linkage has just enough play to move and you can hear the park pawl latch and unlatch while moving it in the play it has. Not sure on this one at all.

Once all this is done and its working right I think I'll be setting up an old 350 engine and trans project I have for when this engine or trans dies, make a semi quick swap to a tougher setup that is actually somewhat reliable.

 

Decided to do a flush and filter while dropping the pan to check inside, not even going to bother now. Back to square one I go, pretty sure the pieces are from one of the snap rings holding things in place since it won't lock up in park now. Sending this pos trans back to where I got it from and hopefully getting my money back.

Really serious on doing that chev 350 mod now, just need some specific parts.

 

Somewhere I just saw an advertisement for a company that specializes in a 350 small block or LS and THM 350 swap into an XJ using a stand-alone computer for TBI or TPI to mate with Jeep's PCM. I'm pretty sure they have something that will work with an Edelbrock or other carb just as well. It would be hard to just eliminate all the electronics in a WJ since the BCM controls an awful lot of stuff on a Can-Bus system. Intriguing idea though.

 

I've been looking at different options for a while, I think I know which place you're talking about but I'm killing off all engine and transmission computers. The 350 I've been working on is carb only and the th350 transmission just needs a tail housing and 4x4 output shaft. The only major parts I'll need are mounts, something easy to build now that I have a welder, the driveshafts since the th350 is a bit shorter than a 42re and custom headers since the space is a bit limited. After that its just electrical and vac systems for the headaches.

If I actually do the swap I'll be keeping the original PCM and electronics inside, the wheel speed sensors and abs system as well as a few other odds n ends too. All I plan on changine is the engine, trans, transfer case and drivesharts for now.

Will need a monster name after its done too.

For now though I'm going to bandaid a trans so I can move my WJ and have some shop space.

 

My 89 Chevy pickup had a 700r4 and NP t/case in it that was just like a 231 (2wd, 4wd, 4wd lo). IDK if to had a left-side front shaft or right-side front shaft. I blew the turbine in the converter, but had to rebuild the whole thing because it had metal particles throughout it. The only electronics in that was to lock up the converter if I remember correctly. My point was you could probably find a 700r4 with a t/case on it easier than a 350. BTW, I inverted the spring in the 4th gear accumulator so it shifts more solidly.

My mechanic has a small mid 60's Ford Fairlane with a Dodge 426 Hemi in it he calls "Thunderbolt."

 

I'm not going to be keeping this transmission because of the particles and chunks, no use having to rebuild it and waste more money when I have another that just needs minor parts that I already have.

​​​​The only reason I'm even thinking about a 350 swap is because I already have most of the parts, including the th350 x2 sitting and waiting for a use. It would be nice to put a th400 or 700r4 in it too but I don't have either atm. All the 350 stuff is out of an old 70's RV and Beauville sport van with changes to heads, cam and intake for more low to mid range power which will make any vehicle climb nicely.

 

I see your point and commend your use of available parts. My GM experience began with a 67 SS Camaro that I raced and proceeded thru several pickups with 305s and 350s until I bought my jeeps. I have rebuilt a couple of TH350s and one 700r4 that was in my only GM 4x4. How do you say "9 mpg?"

 

I started my experience with GM working as an apprentice mechanic, went from dealership technician to real mechanic when I started at a shop that restores cars from the 1930's to the present. Now its just a hobby and for personal vehicle fun since I was injured in 2014 and have since been added to those now disabled.

 

Yeah, it's SOAB to be disabled, ain't it? When I get down on my knees to place a jack, I have to pull on the body or something close by to get up! It takes all the fun out of working on my vehicles. I'm lucky that I found a friend in my mechanic who's a classic and hotrod freak to do the work that I can't handle. He has gone out of his way to fit me into his schedule for an emergency, even if I have to sit and wait, which I don't mind. He only charges HIS price for parts for all his customers! You can even bring your own parts, but he doesn't give any guarantees if you do. Lately, he has hired a couple of Cubans to do the work, but let me tell you something. Those guys know how to fix anything because in Cuba, you HAVE to fix stuff or not have a car! The language barrier can be a bit of a problem though. Once they understand what you want, it gets done perfectly.