Texas heavy duty emissions exemption law

[454HO]

Originally Posted by vtwinsport

Hey everyone,
I've searched this whole site and google but I can't find a reference to a discussion on mid 1970s (75-77 maybe)Texas law that exempted 1/2 tonnes from catalytic converters and egrs/ air pumps, if they were sold as heavy duty. Which usually menat 350/ 400 engine and extra springs and overloader shocks.

Why are you concerned just with Texas law? As far as I know, the state of Texas does not have any emissions laws that are stricter than the federally mandated emissions laws.

This article from the 73-87.com site explains what 'heavy duty' is (it is based on the rated GVW) and the years affected - 1973-1987 Chevy/GMC Pickup Emissions

Now several years ago, starting in 1996, there were several Texas counties that enacted stricter emissions TESTING than the rest of the state. These counties are primarily the ones that include Houston and Dallas/Ft. Worth and the surrounding counties.

The stricter testing includes operating the vehicle on dynomometer with an exhaust analyzer hooked up to it. This is required for all pre-OBD2 vehicle that are 25 years old or less. So not only do you have to pass the visual, it all has to work too. The OBD2 vehicle, which are 1996 and newer, just have to have a scan tool plugged into the PCM and it checks for trouble codes.