Is this Cherokee a 2 wheel drive? In his original post it says he replaced the rear tires with stock ones or something like that... Does that mean the front ones are a different size? Not so good with 4 wheel drive.
By the way where does your temperature gauge run? This does have a 195 thermostat in it I hope?
Mike

first off, yeah, it's most likely the cat.
second, any well qualified technician knows that all 4wd vehicles without front axle lockouts shouldn't be on the rollers.
my tech won't put them up, he'll only do a curb side idle test (sniff test) only.
ontario drive clean is as strict as california's.

i knew this, but asked him why he didn't put it on the rollers, and he told me jeeps can't go on the rollers.
same as towing, it's either 4 wheels on the ground (flat tow with t-case in n and tranny in park) or 4 wheels up (flat bed or dollies).

why cant a jeep go on the rollers or go on a tow dolly

driveline stress. they're designed to use the t-case vicious coupler (242) as a clutch for when the wheels turn at different speeds.
but with 231 t-case jeeps, that's why the passenger side shaft is split, so no power goes to that wheel when in 2wd.

think of it the same way as using 33's on the rear axle and stock tires on the front. all wheels should be turning at relatively the same speed. or at least turning together.

that nonsense
if you are in 2wd or have the tc in neutral the front drive is disconnected
and has no effect on the rest of the system

if you have a full time only TC that would be right but not on the231 or 242

where did you get this info?

it's been brought up many times over the years, so i can't recall exactly where i heard/read this.

but when i was towing for a couple years, any 4wd vehicle had to be on a flatbed or wrecker with dollies. says so in our towing guide book, with no exceptions.

so if you know different, where do you get your info?


http://www.naxja.org/forum/archive/i.../t-966054.html

thats just a safety protocol for towing so some driver dos not mistakenly tow a full time truck on two wheels and mess up the TC

think about it you can have locking hubs on jeeps and trucks with part time TCs
the axles and drive shafts don't turn with the hubs unlocked

well, i'm not about to have a pissing match with you, so i will go with my years of info and knowledge. you can do what you want with your jeep.

same with flat towing, but that's another thread.

to the OP, my e-test tech knows all about the different 4wd models, so you may want to talk to your testing tech about an idle test. may work out in your favour.

I'm not trying to have a pissing match
I just want to know what causes damage towing with front wheels up
I can see noting mechanical that would cause damage depending on the TC of cores
you are basically in free wheel only the shaft is turning along with the oil pump

I have plenty of my own years of info and knowledge
just remember there is what the book says and then there is the real world
sometimes they are the same and some times not

UPDATE: With a new cat installed, the NOx reading were cut in half and the XJ passed smog!!!! Thanks for all the suggestions!

Glad to hear that ou passed the sniffer test.

HIP HIP HORAY!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! you beat it. . . now for 2 years in the future. . .