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Old 12-17-2011, 05:26 PM
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Join Date: Oct 2006
Location: Fort Collins, CO
Posts: 154
Emissions testing in Colorado - Air Care Colorado


I failed my first emissions test, of two. I just spent the last two days trying to get my car's CO% emissions to get under 3.5 at 2500rpms. I could not make it happen. I figure it is because the car came from sea level. But just as I was about to buy a collectors tag for $450 I spoke to the director of Air Care Colorado in Fort Collins at our emissions testing station. He told me that my car only has to pass at the idle speed. What the F!!?

At first I was happy because I knew I could pass. Then I got pissed because I paid a mechanic to help me reach this unattainable goal and then tweaked it myself in the cold for two days.

When you get tested they test you at idle AND 2500 rpms, but this high rpms test is completely irrelevant. I asked the Emissions director guy, he said he knows it is misleading and wants to get it changed.

So the big tip here for anyone trying to pass in Northern Colorado is that you only have to pass the hydrocarbons and CO limits at idle, NOT at 2500 rpms.

If you call the main office you can confirm that because no one else in all of Colorado including the emissions test techs and state endorsed repair shops seems to know this little detail.

Also another rule is that if your car is 1968 and newer you can get an exemption if you show repair bills totaling $700. If you are 1967 and older you only have to spend $70 to get the exemption. There are other rules for the exemptions that are available on the website

To achieve right mix of low HC and CO, set my points gap to about .012, set my timing to around 5 degrees after TDC or advanced of Top Dead Center and tightened my air mixture screws each a 1/4 turn. I increased the idle to 900 rpm which brought down the HCs at that configuration. That had my results at .77% CO at idle and 545 for the HC.

I could never get my CO% under 5 at 2500 rpms, but it turns out it doesn't matter. But beware, the test results read like you have to pass both at idle and 2500 rpms. You DON"T.

Good luck.

1965 220SEb Manual

Last edited by Scutch; 12-17-2011 at 07:15 PM.
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