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kellcats521 kellcats521 is offline
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Join Date: Feb 2005
Location: Atlanta Metro
Posts: 219
Originally posted by dyerkes

I don't disagree - if a car can be modified, and burn cleaner than what the original factory exhaust setup provided, why should it matter whether you do or don't have cats, and other smog related equipment. Unfortunately that's not how the emissions regulations were written. Am I incorrect, doesn't the emission tail pipe test detect whether there is or isn't a functioning cat on a car through analysis of the output gases.

Was your emission (dyno) testing anything other than a measure of CO? The state inspection measures NOx and Hydrocarbons as well.

The tailpipe test detects CO, HC, NOx, and IIRC a CO2/CO ratio. The EPA (and therefore states) also mandates that original emission control equipment is not modified or altered, which includes EGR, CAT, smog pumps, etc. Newer cars w/OBD III will produce a trouble code if any of this equipment fails or is altered, but in pre-1997 vehicles, only a visual inspection can identify issues. Technically, my car fails the visual part of the test, but the person who tested my car either didn't notice that it had no cat (and that the smog pump belt was gone), or didn't bother to check it out. Most of the inspectors are pretty diligent here in Atlanta, but with a Porsche turbo there appears to be a 'lot' of exhaust stuff in a small place....

Anyway, I passed all of the imperical tests - HC, CO, NOx, and CO/CO2 ratio, without a cat or operational smog pump.

Pat K
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Old 07-10-2007, 11:29 AM
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