A Couple of XJ Questions

8379qtj10

Well-Known Member
Joined
Jan 22, 2007
Location
Washington N.C
My father has a really nice 1991 XJ w/6" lift and 33's.
He has a new commander and the XJ has been sitting and does not get driven much due to a couple of problems. I want to buy it from him and need some info on repair.
Problems...
1) Engine is newer but it will run great then for no reason it drops a couple of cylinders and runs like a dog...then it will run great again. So whats up??
2) Syncro's are getting bad in the 5 spd. and the chain in the T-case is past is strech point and slips in 4 low. Can in be upgraded or is a stock replacement good enough for off-road use??
3)How hard is it to upgrade axles and do I really need them??
It has 3.08 (or something like that) If I didn't swap axles what would be a good gear choice??
Thanks in advance for your ideas
 
well I cant help you much on the first 2 but my thoughts on the 3rd question are it depends on which rearend you have in the jeep as to whether its worth swapping. If you have the Dana 35 then its worth swapping out. You could go with a chrysler 8.25 also found in some xj's, it will hold up to 33's and is a direct bolt in, no modification needed. Or you could go with an explorer 8.8, not a direct bolt in, but would have disk breaks and same bolt pattern as the jeep and durable. As for gears, I would go with 4.56's. Hope this helps some.
 
well as far a the engine goes id look at the coil first if its starting to go it could cause you to loose spark energy. Are you sure it actually losing cylinders or does it just start to run like crap. If your not sure it could be anything from the mass air flow sensor to clogged fuel filter, or bad fuel pump...or ecu...the list goes on and on. We need more info as to what exactly is happing other than it running good and then like crap..."haha sounds like all the jeeps ive ever know". as far a the 5 speed you could look in the junk yard for one or have yours rebuilt..if your planning on any hard core stuff your going to need a better trans than jeep ever put in an xj/yj. Ans last but not least you should have an np231 transfer case and there are upgrades available all over for it. THe stock chain should hold up to the "2.5l or 4.0l" unless your looking at engine swaps or superchargers. Search at Naxja.org lots of XJ info there!
 
I have a 95 xj it had similiar problems with the motor. I changed ignition coil, fuel pump, plugs and wires it did not fix the problem. The last thing i did was change the o2 sensor and header that seemed to fix it. I had a crack in my header, the crack lets in outside air and messes up the o2 sensor reading.

I don't know to much about transmissions but if you are going to replace it I know where you could pick one up for around 3-400 dollars. Do you live in little Washington? If so on 264 towards Greenville their is a place called Kenny's Used Jeeps. He sells transmissions pretty cheap.
 
just put a used tranny and t-case in. an ax-15 and 231 a fine. my old XJ had 38s and the aw4 and np231 worked great. no need to "upgrade". especially with 33s.

and as for axles....if you are sticking with 33s and not going any bigger then i'd leave them alone too. any bigger and i may think about upgrading.
as for gearing, it may not hurt to get lower gears, say some 4.10s or something.
 
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