Just got a 96 XJ this past week and so far I've failed emissions twice, both being high nox. The exhaust manifold was cracked so I replaced it and got the number down from 4.7 GPM to 3.7 GPM (3.5 or less to pass). Just wondering what I should look into next? No cel and everything else passes with flying colors. Any help is very much appreciated. Thanks!

 

Just because there is no CEL showing doesn't mean a code/codes haven't been tripped. Take it and have it scanned.

 

Move to America.

I am not kidding. A 1996 vehicle should not be subject to that BS.

 

My 96 still has emissions inspections until it is 25 years old...

 

Agreed, I don't know how people deal with that crap, I wouldn't live in a place that did emissions inspections.

 

SAD!

 

CA dont care if your vehicle was built in 1976.... its still going on the rollers and getting probed up the rear.

High NOX is saying its running lean. Might want to try to replace the o2 sensor next.

 

Emission testing is just another form of tax.

 

Try running a tank of gas with injector cleaner. Or maybe pull the injectors and inspect/clean them.

 

Ran some lucas fuel injector cleaner when I got it. Installed a new O2 sensor today and it still failed. I'm thinking there's a good chance it's the catalytic converter as it looks like the original and has two good dents into it. If that doesn't do it then I have no idea what to look at. Appreciate all the replies, this emissions crap sucks.

 

Stop firing the parts cannon. Start testing. Yes, it could be the cat, but check the easy stuff first. Basic tune-up. Plugs? Wires? Cap & rotor?

If you can spring for a scanner it would be good to watch your fuel trims to see why it's lean. It might be that you still have a leak into the manifold. Might not have seated it properly when it was replaced.

 

I aint even American, but last time I went to skool, Colorado was one of the 50 USA states ?

@ the the OP, If the Cat is original, I would replace it as a matter of course...that is not "parts canon" imo, but simply replacing an item that has reached end-of-life cycle

I would also replace the spark plugs unless they are known to be well within lifespan

 

Last I heard and that's been maybe 5yrs ago DaimlerChrysler will still replace the original catalytic converters on vehicles listed in a recall. The original owner of my '96 XJ payed a shop to replace hers not knowing about the recall. Can't hurt to give them call if the OP feels it's the original cat.

https://www.epa.gov/enforcement/daim...ion-settlement

 

Hey thanks for letting me know about that. Put in the vin on Mopar's website and it said the recall was already done. Funny thing is though, I found my 2000 XJ still has an open recall for the intake manifold shield.

 

You need a scan tool to see what your fuel trims are doing so you can tell when you fix it.