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Failed Texas Emission test

redwagon

NAXJA Forum User
Location
Spring, Tx
Failed Test, Added the emission test in a bottle with no luck.. Cat was repalced in 97. Changed oil too. Funny thing I only have 4,000 miles since last year inspection when I did pass . The print out shows high nox at 15mph but cleared ok at 25mph
 
What year is your XJ. Mine did that samething, I changed the Cat and egr valve. Passed. So take a look at the EGR, replace it if needed. Also your O2 sensor could be bad, but I would look at everything else first. The emissions guy said most people that fail at his station are exhaust related. Muffler, cat and O2. Juice
 
They sniff like crazy in dallas/ft worth. I bet I went back 4 times before passing.

Mike
 
I'm with the thought on letting the emission pass stuff work (many of em suggest that you run em for a few hundred miles and don't retest while their product is in the tank - they're supposed to help de-carbon your top-end which, strangely enough does lead to high NOx values.@!)

While you're waiting - you may wanna consider looking over your EGR system (clean the valve, inspect the vacuum lines etc)..

GM has a product (engine Top Cleaner) that'll strip most of your top-end carbon deposits in a few minutes ---

or i could be that your cat has finally crapped...

NOx levels are intended to look for high combustion chamber temperatures - carbon build-up and bad timing are common causes
 
Take a look at your prior test results... it may not be your Jeep. I failed the last time here in California thinking my XJ needed some TLC.

Not the case ... I looked at readings from the emission test two years prior and found our dysfunctional state tightened the emission standards since the last go around -- it actually tested cleaner than the results from 2 years ago.

Nevertheless ... I was forced to change out the Cat to get the thing to pass the new Davis-Bustamonte emission standard--- hope those guys go down in flames.
 
Failed Emissions Too

Redwagon:

Failed NJ emissions last fall because of NOx. EGR was fine. It is easy to check by FSM checks. Usually Ox Sensor is not the problem with high NOx. It is usually the Catalytic Converter. Had mine replaced with a universal cat at a good reliable garage and passed emissions (just barely) after the replacement. Have about 14 until I need another emissions test. Any others have any similar experiences?

XJDanny
 
the cal test

Yeah I flunked it a couple years ago, the lead wire to the O2 sensor was busted-- one test facility moron didn't catch that during the visual inspection. Anyway, replaced it and no problems. Just passed again a couple months ago after a homegrown tune-up.
 
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