Hi. I have a 89 4wd Cherokee, 4.0L, inline 6 cyl. I have failed emissions 3 times due to exceeding the NOX standard. I'm not failing by much (around .85 over). So here's what I've done to it, but it still fails the NOX: 1. Replaced spark plugs & wires, replaced distributor cap & rotar, replaced the CCV hoses, replaced all the other vacuum hoses, changed oil & filter, replaced EGR, (can't set timing on this engine), and prayed. Can anyone suggest anything else? At this point I'm open to anything, except bribing them. Jail isn't my thing. Help, please! Thank all in advance.

 

its failing NOX for 1989? there is no NOX standard for 1989 so thats a cool trick.

 

Check your catalytic converter.

 

[QUOTE="cdawall"]its failing NOX for 1989? there is no NOX standard for 1989 so thats a cool trick.[/

What it's failing is the emissions inspection results. The applicable standard for Oxides of Nitrogen (NOX) in grams/mile in Phoenix, AZ is 4.50 & my jeep keeps putting out 5.40+\-.
I'm passing the Equipment tests perfectly.

 

I was afraid someone would suggest that. I'll prob end up having to do that. Thx!

 

I used to have an "86 Cherokee with the 2.8 V-6 . I had never ending problems with getting it to pass emissions . I would always end up getting a can of" guaranteed to pass " . It's about ten bucks a can .

 

Also.... drive that thing up some tough freeway grades and 70+ mph freeway driving. Get that cat nice n hot.

 

I've noticed no one said the obvious. It could be the O2 sensor. make sure all the cables are good and not burnt. Mine fail the exact same way! I changed the O2 sensor and the EGR valve, went back and dude said
"very good, like new car" lol

 

Why in the world had that not crossed my mind??? It absolutely could be the problem. I'm off to Autozone today, I hope they carry this part for my Cherokee. Thank you sir!

 

I just replaced a cat on a 92 the price tag was only $110 and with a little heat and beat it was in and over with.