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Discussion Starter · #1 ·
I just had an emissions test done, everything passed except NOx which had a reading of 4.466.
What would cause this to fail? I don't want to go to a shop and get charged out the a** for something minor.
Also, they could not find the OBD, is that a problem?
Thanks for any advice.
2000 TJ 2.5l manual
 

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what meathead did the check, your plug in is at your left knee, just look under the dash on the left, i have a 98 an the 2000 should be the same, some part stores sell a fuel additive that will help you, my stroker engine passess, i run high test, they plug in an um done, thanks see ya next year.
 

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Fuel additives don't normally help in this situation, and no, neither does high octane gasoline help either... which can actually make it harder to pass smog tests.

Was your engine completely warmed up when they ran the test? If the engine isn't at or close to its normal 210 degree temperature, it won't pass. That can be caused by the wrong model thermostat having been installed, it needs a 195 degree thermostat, or simply the smog tech let your engine cool off and it was too cold when he ran the test.

No guarantee this potential temperature issue is why yours didn't pass but it was the cause of mine not passing years ago.
 

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Discussion Starter · #5 ·
I had to drive about 15 miles to the site, then sit (idling) for about 10 mins, so I don't think temp was the problem.

As far as the OBD goes, I looked under the dash and found nothing looking like the plug. I snapped a pic to show what I saw. The bracket in the photo is right at my left knee.
 

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FYI:

High NOx and low CO=high combustion temperature
Low NOx and high CO=low combustion temperature

NOx and CO are inversely proportional. The catalytic converter changes the ratio but straight out of the engine the numbers don't lie.
 

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I had to drive about 15 miles to the site, then sit (idling) for about 10 mins, so I don't think temp was the problem.

As far as the OBD goes, I looked under the dash and found nothing looking like the plug. I snapped a pic to show what I saw. The bracket in the photo is right at my left knee.
If I'm not mistaken, the gray part with the red in it is the OBD port. I'm sure I'll be corrected if I'm wrong.
 

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Discussion Starter · #8 ·
So I had my catalytic converter replaced along with replacing the muffler. Went back to re test and it failed again.
This time the NOx went up to 6.6679, CO2 went up from 364 to 462, but HC and CO went way down.
Thus is starting to drive my crazy. And broke too.
 

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In colorado it is the sellers responsibility for the vehicle to pass. Unless it was a tow away or salvage. Private party seller or dealer????
 

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If I am selling/buying a used car is an emissions test needed?
Yes, you are required to have the emissions tested on a used car for sale even if your prior emissions test period is still valid. There is one exception to this rule. If the car for sale had a four year exemption on it (because it was a brand new car) and that exception has at least 1 year or more left on it than an emissions test is not needed. The responsibility of getting an emissions test done on the used car for sale belongs to the seller of the vehicle. This is done to ensure that the buyer is not purchasing a vehicle which is in need of immediate repair. The buyer will need the emissions testing paperwork from the seller in order to register the car
 

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Discussion Starter · #15 ·
cr wrang said:
In colorado it is the sellers responsibility for the vehicle to pass. Unless it was a tow away or salvage. Private party seller or dealer????
Dealer, he bought it from an auction, but there is nothing on the title about salvage
 

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Did they give you a voucher for the emissions??? The dealer should know better, and that it is their responsibility. You might be able to put pressure on the dealer to get this taken care of. I only see 1 drawback though,, and that is the amount of time you have had the Jeep. I really do think they are resp however.
If need be call the troubleshooter, or dealer licensing board. They should have given you a new emissions report or at least a voucher for you to get it done.
 

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Discussion Starter · #17 ·
I did get a voucher for the test. I didn't realize that on the voucher is says to get it done within 3 days of purchase, which seems like a loop hole for dealerships to get out taking care of it if you take too long.
I did call them after the second failed test, and e-mailed the test results to them. The dealership is about 60 miles away from me, so I can't get there until monday
 

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Ya the dealers here are more and more pulling this crap. Not sure if it is really an out for them though. If they don't want to work with you though I would make some noise. Tom Martino troubleshooter.

Seems combustion temps to high. Make sure cooling system working good. Proper anti-freeze mix. Thermostat. O2 sensors, Pull the plugs look at them to see if maybe you are running too lean.

It seems your levels went up because engine now running more efficient. After installing cat back.
 

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Discussion Starter · #19 ·
So, I went to another mechanic, and after doing his tests, he was leaning towards a bad pcm. He took it to another shop around the corner with better computer equipment.
Pcm was fine, but he detected a bad o2 sensor that the first guys equipment didn't pick up on. So he replaced the o2 sensor after the cat.
Just got back from my third emissions test, failed again still for the same thing. This time the NOx went down a little, but still not passing...
This sucks
 

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I would start with a basic tune up, check the plugs to see if they are all burning or if some are fouling. From there, check all vacuum lines. After that I would look at catalytic converters. I'm not sure if yours has one or multiple. Make sure you are on 87 octane as well.
 
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