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Got an emissions question...

Chad95XJ

Chad95XJ

NAXJA Forum User
Location
Phoenix, AZ
I just ran my 95 XJ through emissions. It passed the hydrocarbon and carbon monoxide tests with flying colors. The nitrogen test was another story. It failed with a 3.30 against a maximum of 3. I backed off the timing a bit thinking that would solve it but it failed again, this time with a 3.08. It helped, but not enough. I'm thinking maybe the O2 sensor? The Jeep has over 230K on it, and the one on it looks to be the original, or quite old. I'm gonna have to pay for the next test regardless, but I really want to not have to try a fourth time. If anyone has ideas, I would really appreciate it!
 
Wow, could be a lot of things. Here are things that come to mind.

*Vacuum leak
*Ignition tuneup stuff. Plugs, wires, cap, rotor
*Evaporative system
*Ensure engine is at proper temp (use p+s thermometer on thermostat housing; temp should be between 200-210)
*Internal engine condition (perform compression testing)
*Ensure fuel pressure is within spec
*Excessive carbon buildup. Decarbonizing could be attempted ; ie: Seafoam induction or equivalent product might help
*Catalytic converter is degraded and no longer effective

Let us know what you did and how the test comes out next time...Good luck!
 
Last edited:
Well, I can rule a few of those out. I did cap, rotor, wires, and plugs in March, and it passed the evap test. I put a new oxygen sensor on it, and Mopar makes some pretty good combustion chamber cleaner that I can get reasonable. I think I'll give that a shot and see if that works.
 
NOx emissions are most commonly from leans burns. the excessive heat causes NOx emissions to rise, so definitely check for vacuum leaks, running a fuel cleaner wouldnt hurt
 
I'm curious as to how OP was adjusting the timing?
 
Emissions:

Be sure you have a fresh oil and filter change. Then run a full 30 minutes highway cruise, (to FULLY warm up and to clear out the cold start carbon etc.) then right straight into the test while hot.

Orange
 
To answer the question about my timing, I work for a Chrysler dealer in Phoenix, so I had a tech I'm friends with plug it in to the computer and retard the timing. We checked for vacuum leaks at lunch today and couldn't find any, so we're banking on it (hopefully) being the O2 or dirty CC.
 
5 years ago I failed miserably on my smog. Everything was WAAAAY off. In CA I was dubbed a "gross polluter" and had to go to a gross polluter smogger.

Before I went I:

Changed the oil
Tuned up - plugs, cap, rotor, wires
Cleaned EGR, IAC

Didn't help, so I:

Found and fixed every possible vac line including the whole CCV and cleaned the throttle body. It still failed but was some better. The shop told me to get:

New gas cap
O2 sensor

Passed with super numbers, so after spending lots of time & money I had it narrowed down to EVAP or O2. But now everything is tight and almost new. Passed every time since.
 
emissions testing is LAME. i think it's just a trick to make money. not to mention getting older cars off the road, despite many of them being in good shape. i don't hafta pass, but i feel for those who do. i've seen many sweet rides, (mostly jeeps) hafta part with their doting owners in favor of something really gay that passes emissions.
 
ParadiseXJ said:
...but yeah, it's probably a trick, or a commie plot.:farmer:
Click to expand...

LSD Zombies (Liberal Socialist Democrats) don't like to be called "commie", they prefer "enlightened" or "progressive". :twak:

So, in the name of Global Peace and Harmony, and for the children, please refer to the LSD Zombies as "enlightened LSD Zombies" or the equally correct "progressive LSD Zombies". :D

(When I told my Sister Liberalism is a mental disease and or defect I thought she was going to have a stroke!)
 
The most common cause of NOx is heat. On a jeep, I was told by the Head of the Salt Lake County Emissions testing program to clean the CCV. I was asking him because I was also good on HC's and CO's but running borderline on NOx and I was getting my certification for work from him at the time. Fuel additives will get you passed, but it wont fix the problem, and if it is running high than your jeeps not running 100% right. Also don't use an additive that has lead in it. It will fu** you cat up worse. A new cat is also a good idea, but its a band aid to some extent too.

If its the LSD commies putting it in place hear in utah, I'll have to thank them for it. If you could only see the winter air hear after a couple weeks of no snowstorms. Makes my lungs hurt.
 
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