1994 XJ running issues - JeepForum.com
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post #1 of 8 Old 11-26-2019, 10:46 AM Thread Starter
nothingbutdarts
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1990 XJ Cherokee 
 
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Location: Bailey, Co.
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1994 XJ running issues

I bought a 1994 XJ with 120,000 miles on it last year, it never ran good when test driving and I couldn't drive it hard to really see how it ran because, I had to remove the dreaded broken motor mount bolts. After doing this I have numerous issues with it, I believe the rattling CAT converter has let out some of the honeycomb & will plug the inlet of the muffler under full acceleration then you can barely go 5 MPH and it wants to die. On a 1994, if I were to just pull the cat & gut it, will it then mess with the air/fuel ratio because of the O2 sensor after gutting and cause issues?
It also needs the usual cracked exh. header replaced. It seems sometimes when started on a cold day (35 degrees) it acts like a carbureted engine in that it seems like the choke is stuck closed and being flooded, what could cause this? Maybe the O2 sensor in the cracked manifold is sending the wrong signal because of the crack?
Last question, is a 1994 a OBD2 and can be read with a cheepo scanner? I remember my 1990 could not be read without a special scanner.
By the way, I have not driven this in at least a year, it just sits, I have a 1996 XJ with 270,000 as a driver.

Thanks All!!!


Last edited by nothingbutdarts; 11-26-2019 at 10:48 AM. Reason: added info.
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post #2 of 8 Old 12-01-2019, 02:18 PM
CJ7-Tim
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You cannot diagnose problems very well when you have known existing malfunctions. Are all of the tune-up parts fresh ? Have you tested the coil ?

Install a new exhaust manifold, and a new cat converter. It probably needs new O2 sensors as well.

1996 was the start of OBD-II but you should be able to get the OBD-I to display trouble codes on the instrument cluster.

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post #3 of 8 Old 12-01-2019, 07:54 PM Thread Starter
nothingbutdarts
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I did put a rebuilt NAPA distributor & plugs in it.
How do you get the codes to display on the instrument cluster?
Thanks!
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post #4 of 8 Old 12-06-2019, 02:22 PM
KF4SQB
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The only way a cat can cause an issue is if it is clogged. Even on vehicles with a post-cat 02 sensor, the post sensor has no effect on the fuel/air mixture delivered to the engine. It is only there to monitor the operation of the cat. Cats are actually very rarely clogged, unless there is a serious issue with the engine. You can certainly try removing the cat (short term, you really do need to replace it if it is bad), and see if that helps anything. As always, take Tim's advice to heart. He's one of the most knowledgeable people on here! If your cat is clogged, you need to be looking to see why. With a properly running engine, they should last for many, many, many (did I say many?) years and/or miles.

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post #5 of 8 Old 01-07-2020, 10:42 AM Thread Starter
nothingbutdarts
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What I believe is getting clogged is the honeycomb that has broken into pieces and causing a high restriction to flow. If you were to hear all the rattling noise in the CAT it might make you a believer. Between myself and my daughters we have had 6 1987-1996 Cherokees, all have had CAT rattling issues and have replaced maybe 2 of them because of the rattling. My daily driver 1996 has been rattling for a few years with 270,000 on the clock, still gets around 20 MPG and runs good. For $280.00 for an OEM fit CAT I will keep driving it. My 1990 Cherokee I sold with 320,000 miles on it.
When it warm up this spring I will drop the exhaust on the 1994 and have a look see. I would really like to get the 94 running.
Thank You all for the advice!!
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post #6 of 8 Old 01-07-2020, 10:54 AM
tjwalker
It's the crank sensor!
 
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FYI, here is the "key-on, key-off" technique for retrieving codes on an OBD1 Jeep (91-95). Hope this helps....
------------------------------------------------------------------------------------------

Retrieving OBD codes on the Jeep Cherokee (XJ) OBD1 Models: 1991-1995

1) Start engine (if possible). Move transmission shift lever through all positions, ending in Park. Turn A/C switch on and then off(if equipped).

2) Turn engine off. Without starting engine again, turn ignition on, off, on, off and on within 5 seconds. Record 2-digit fault codes as displayed by flashing MIL.

3) For example, fault code 23 is displayed as flash, flash,4-second pause, flash, flash, flash. After a slightly longer pause, other codes stored are displayed in numerical order. When MIL begins to flash fault codes, it cannot be stopped. Start over if count is lost.

NOTE: A "5-5" will always occur to signal the end of the sequence. Some will flash the "1-2" code indicating a recent battery disconnect even if you haven't done it. Ignore these two codes, and mark down all others.

99 Cherokee, 4.0 AW4, NP242
Past Jeeps: 49 Willys, 81 Scrambler, 88 Comanche
Without "data", all you have is an opinion!
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post #7 of 8 Old 01-07-2020, 11:09 AM Thread Starter
nothingbutdarts
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If by chance you haven't had a battery in it a while, put one in and then try to read codes I would guess that there would be no stored codes??
Thank You for the detailed info. on pulling codes!!!
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post #8 of 8 Old 01-07-2020, 11:39 AM
tjwalker
It's the crank sensor!
 
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Yes, with battery removal, you will likely have no codes.

But if the problem still exists..... after running it for a while, the codes will return.

99 Cherokee, 4.0 AW4, NP242
Past Jeeps: 49 Willys, 81 Scrambler, 88 Comanche
Without "data", all you have is an opinion!
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