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1990 Renix question :)

XJ4Christ

NAXJA Forum User
Location
Topeka, KS
I was wondering what is the deal with companies labeling XJ parts for things like the engine (throttle body, etc) and even the exhaust manifold, exhaust pipes etc being listed "for 1991 or 1993 + years 4.0 liter. I know that the High Output 4.0 came out around that time etc, but I cant ever find things that according to the description fit my 1990 which has the standard 4.0 (not high output). I take it there is a difference, but it always seems like my year XJ is "oddball" like in it is a transition year between "Renix" and the newer style. I thought maybe it is due to some XJ's not having the 4.0 in 1990 and that is why they list 1991 plus?

I found out the other day doing my brake pads that they gave me wrong ones (for 1990 plus i guess). AFter looking my pads were for 1989 XJ.

If the stuff for the high output would fit on my regular 4.0 and they just dont mention it, I would like to know or if it would have to be modified etc :).

Also what would be the difference between 1991 and 1993 rig on the exhaust pipe between the cat and the exhaust manifold (just curious).
 
Some of it works fine, some of it doesnt. The OBDI setup had some changes (of course) As for years that it will work for, basically that is a lsit of "guaranteed" to work vs might work.
 
Much of it has to do with California regs - in order to be "California legal," there's an onerous approval process, and it has to be followed for each variation of control (OBD-I, OBD-II, pre-OBD, points & condenser, ...)

In order for the company to pay for it, they have to be reasonably assured that there is a market for it. RENIX (1984-1990 XJ/MJ w/AMC engine) is very much a "niche" market.

If they can't make it "fifty states" legal, they're probably not going to make it "49-states" legal, either. And, there are enough differences in RENIX parts that they're generally incompatible with ChryCo OBD parts, save some sensors and the like (throttle bodies are different, cylinder heads were revised, control system - obviously - is different, and the like.)

You're a victim of the state we both live in - and the fact that these asinine rules are made by people who know nothing about technology, merely politics and bureaucracy.
 
Also what would be the difference between 1991 and 1993 rig on the exhaust pipe between the cat and the exhaust manifold (just curious).

Should be no difference there as far as I know. I believe they didn't really change anything on the exhaust until 1996 when they went to OBD-II

Here's a rough break down of real parts commonality.

Suspension stuff: 1984 - 2001
4.0 Engine Stuff: 1987 - 1990 RENIX, 1991 - 1995 OBD-I, 1996 - 1999 ODB-II w/Distributor, 2000 - 2001 OBD-II w/Distributorless
There are changes in between, this is just rough. Expect most plugs to be different between 1996 and 1997, parts are mostly the same though.
Front brakes & Knuckles: 1984 - 1989 / 1990 - 2001
Rear brakes: 1984 - 1989 had a lot more options. 1990 - 2001 there were only two different styles "Big" or "little" (towing or no towing, the early model BIG is bigger though)
Body & Glass: 1984 - 1996 / 1997 - 2001

That's all I can think of off the top of my head. There were changes throughout the line here and there. Also you can put 2001 fuel injectors in an 87 (they flow a tad more but not enough to fork out extra money for).
 
Cool thanks for the replies. So I take it that I cant use the exhaust manifold and the exhaust pipe that fits between it and the cat off a 1991+ XJ in the parts stores due to sensors and computer setups on my 4.0 engine (non high output). That sort of sucks as i have read that you can get some good power gains from upgrading...
 
So I take it that I cant use the exhaust manifold and the exhaust pipe that fits between it and the cat off a 1991+ XJ in the parts stores due to sensors and computer setups on my 4.0 engine (non high output).

Yes. The HO (91+) exhaust manifold does not include the bung for the EGR system (HOs do not have an EGR valve).

I wouldn't worry too much about horsepower gain, the OEM manifold is pretty damn good and you can still at least get a Borla for a Renix XJ. I like my Renix Jeep, it's easier to work with than my '96 Jeep.
 
the intake and exhaust manifolds are different. which includes the throttle body, corresponding sensors, vacuum lines. and like stated 91+ have the OBD diagnostics whereas renix XJ's do not.
 
Cool thanks guys :).
 
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