In previous years I was able to get away with emissions pretty smoothly without much trouble(switching to stock ecu,warpspeed ypipe, custom 2.5 inch exhaust). But it looks like colorado is tightening up the requirements and I am failing the NOx part of the test. Here are my results:

HC - .691 lim: 1.2
CO - 3.28 lim: 15
NOx - 1.61 lim 1.5

As you can see I am nearly .1 off from passing the NOx, this is actually the second run because I came back after a spirited 15 mins of driving around and completely filling up the tank(reccomended by the tech). My first pass was 1.9 on NOx and he thought this would do it but im still off.

I read up on the NOx thing and the most common thing to do is clean out the EGR and check the hoses. Is this the best way to fix it...anything else i can do that is simple to drop it down to pass?

 

yep, cleaning/fixing the egr should do the trick. NOx emissions comes from oxygen and nitrogen molecules binding together with the high heat from the combustion. the egr lets some exhaust back into the intake in order to "cool" the combustion, not allowing those molecules from binding together. sounds wierd but that's what it is. The egr's job is basically to reduce NOx emissions.

Some people posted threads of egr's completly clogged up and what they did to remedy the problem, and that might be your problem aswell.

 

anyone have any tips to doing this...i think i saw a thread a while back about this, someone had a doc about thoroughly cleaning the EGR?

 

That's correct. EGR is the biggest culprit for high NOx readings.
Also, don't go for a spirited drive before the test. You want the exact opposite. Any good tech knows to let the car cool down for hours, then start it and run the test quickly. The spirited driving technique is good for keeping the other gas levels down.

Unfortunately, there is no easy fix for this. You'll have to spend the time to clean the EGR system or pay someone to do an upper cylinder head cleaning to remove carbon deposits and lower the compression. However, there are a few little tricks you can do to help your cause. Have your cooling system be nothing but water and a full bottle of water wetter. Also, use the highest octane gas you can find, even race gas. These two tips are relatively cheap and easy and will keep the cylinder heads temps down which in turn will lower your Nox readings.

 

Perfect. The man is a genius.

 

Thanks for the info, i think ill go ahead and start to clean out the EGR and try this waterwetter...you think I can get away with an ocatane boost additive for emissions?

 

An octane booster will do very little to increase your octane points, unless of course you added A LOT of them and had very little gas to begin with. If you're looking to increase your octane points, race gas is the way to go, skip the octane boosters.

 

Hey man if there are any Inspections shops off of Federal blvd (Denver) go to an Asian one, slip him an extra $25 or more and he'll pass you. I know this for a fact that this'll work. Plus it helps if your Asian. But if not then money talks and bull$h!7 walks.........

 

haha good old federal, if i dont pass legit this run ill go done there and pay them a visit...appreciate all the help guys.