Emission Test issue

[TWDJ]

Registration is due, so I had the YJ "smog checked" this morning and ran into an issue.

Here in CA, tests are done at 15MPH and 25MPH on an actual dyno. The 25MPH test was passed with room to spare, but the 15MPH test failed on high NOx emissions. Any of you engine gurus have an idea where to start?

Engine has ~160K miles and runs well. All hoses, tubes, belts, emission controls are installed per factory ... 5K miles ago it passed smog with no issues. The first thing that leaps to mind is the oxygen sensor, but I'm open to all suggestions.

Thanks!!

 

[Megamole]

Check your egr valve make sure it is opening and closing. You can check by using a vacuum to open it or some you can push the diaphram with your fingures. If it is working the engine will run rough or stall.

I have the opposite problem, high carbon monoxide levels, not to sure how to fix them, was told high co means rich running engine.

 

[90growler]

I have the opposite problem, high carbon monoxide levels, not to sure how to fix them, was told high co means rich running engine.

Same here....I have replaced every part of my emmissions system trying to fix the problem with no luck. It still runs rich and cannot pass emmissions. I had to rig an address in a different county without emmissions to get a tag. Very frustrating.....:x

 

[guysmiley]

Nox is caused mostly by high cylinder temps. Make sure your egr is working properly, most likely it is because you passed the slower test. Make sure the vehicle is not running hot. Too lean conditions will give you high Nox. In Jersey here, we have the same type dyno test but must keep 15 mph at less then 3000 rpm. The best way to get by Nox is lower the timing a bit, if you can, and put high test fuel with octane boost. The higher octane burns better, less detonation, thus less Nox. Do the octane trick with Sunoco ultra fuel first. Wont cost you anything more than higher grade fuel and a few bucks of octane boost. Let us know how you make out
Guysmiley

 

[Megamole]

Smiley any trick to getting the co lower. I am in Northern Jersey, just fail the emissions with high co. Need some help getting it passed. We should hit a trail some time when I get some issues sorted out with the jeep!

 

[Sparky-Watts]

You might try giving it a shot of Sea Foam before going in for the test. They also make a product that will almost guarantee that you pass everytime. I'll see if I can find a link.

 

[Sparky-Watts]

Well, this didn't take long.

Sea Foam Engine Treatment

To help pass emissions tests – high emission numbers are usually caused by extreme carbon build up, dirty emission control items such as: pcv valve, egr valve, oxygen sensors or bad spark plugs and wires.

Your service technician can provide a pre-emission test service that includes SEA FOAM MOTOR TREATMENT as a cleaning agent to help pass emissions tests.