Hi,
I just Failed My Emissions test because NOx emissions were 2139 ppm instead of the legal 614 ppm. Everything on the car is brand new including the engine, which has approximately 18 miles on it, as well as New Cat, Exhaust, Headers, and EGR Valve. The engine temperature was high though(around 200 degrees) when being tested. Would having a new engine + exhaust contribute to such high NOx emissions?
The other readings were acceptable with HC being 52 and CO being 0.02. I am really stumped as mostly every part on the engine has been replaced, and the car seems to be running great. Also on the way home from getting the emissions tested there was a slight rotten egg smell? Would this be due to the new exhaust? Does the engine need to be broken in more or need to be driven more? I would gladly accpet any input. Thanks

 

Sounds like it's running rich, the rotten egg smell is an indication of that. Probably why you failed the test also. That's where I'd look.

 

Hey, thanks for your reply. When the engine was first started, it did run extremely rich, and the black smoke and spark plugs confirmed that. But the problem has since been fixed or so I thought? The cause for the engine to run rich before turned out to be a bad chip. But since then its been fixed and the plugs now look good and the car runs 100x better.
Would running rich before have contributed to the high NOx reading? Like for the short time that the car did run rich, would it have left deposits that could have contributed to failing the test??

 

you need to check your timing it is one of the biggest contributing factors to high nox, yours has to be advanced quite a bit, set it back to 6* and you should be fine.

 

checking the timing is a good ideal, but with NOx that high caused by timing, i believe you would be getting a fair amount of ping.
also, i must disagree with it being rich, if you were too rich, that tends to lower NOx.
i think you may be a little on the lean side, 0.02 CO is a pretty low reading, but with a HC of 52 i think your close to where it needs to be. a good work cat can easily cover up a rich condition, some pre cat readings would really be needed to know for sure. you may want to take a look at the data stream & check for codes & see what your O2 sensor, BLM & INT readings are.

your engine temp was fine. there isn't much difference on NOx production from around 120~230 degrees.

take a look at your EGR valve, solenoid, & the vacuum hoses for it.
the vacuum port for the EGR is a ported source, it should have vacuum on it when you open the throttle & no vacuum with the motor at idle. plain intake vacuum is too low to work the valve under light acceleration.
if you have TPI, look for the vacuum port on the bottom left side of the throttle body. for an ideal of where it is, go here, https://www.thirdgen.org/forums/tpi/...pass-smog.html
and go to the #12 post made by me & look at the Attached Image, where the red circle is, behind the throttle cam is where the EGR vacuum port should be.

on the rotten egg smell, that can be caused by too rich or too lean. if it was mine, the first thing i would do is make sure it has no codes & is getting into closed loop & check my O2 sensor, BLM & INT readings, if they look good then wait till you have some miles on the cat, i have seen new cats cause it. if it is still doing it after you have about 500 miles on it, try switching brands of gas.

 

First off, what type of emissions test are you subject to. Is it the dyno (ASM test), or the two speed idle (TSI test). NOx is created from extremely high cylinder temperatures. The reason your car has an EGR valve is to introduce inert, and potentially cooler exhaust gas to cool the cylinder. Also, this may be due to over advanced timing.
You stated in your post that your car was running hot at around 200*F. Did the inspection mechanic have a fan installed in front of the car? Our cars are very succeptable to overheating due to the grille and radiator position, ESPECIALLY when timing is too far advanced. The lack of a fan during the inspection could also lend cause to this concern.
Also, your ppm hydrocarbon count seems a little low. I would suspect that your timing is too far advanced.
If i were you, I would:
1. Reset the timing to specification (unless your motor is modified)
2. Check for proper EGR system operation
3. Insure that the tech uses a fan during inspection.

Hope that i could help. -Bob

 

Also, I forgot to adress the rotten egg smell. This is most likely from your 'new' catalytic converter especially with the high cylinder temps associated with the high level of NOx emissions. The cat may be overheating. -Bob

 

Also, I forgot to adress the rotten egg smell. This is most likely from your 'new' catalytic converter especially with the high cylinder temps associated with the high level of NOx emissions. The cat may be overheating. -Bob