Cusser
+1y
Well, the Cuss lives in Yavapai County, Arizona, where there are zero emissions.
Mrs. Cusser lives in Maricopa County, AZ, which has some of the strictest emissions testing in the country, goes back all the way to 1967 models. So her Yukon and my youngest's '98 Nissan undergo testing as they are registered by her (if youngest's Nissan fails the test in January, I'll "buy" it and register it as mine, but I apparently fixed its check engine light 3 weeks ago by simply unplugging and plugging back in the throttle position sensor).
First question is: are you failing because of high levels of HC, CO, or NOx, or because some inspector can see capped-off vacuum ports because you now sport a Weber?
What I used to do for my B2200, my 1971 VW, and 1970 VW was to clean or replace the spark plugs, new air cleaner element, points/adjust valves/ ignition timing on the VWs, and lean out their carburetors and increase the idle speed to about 1100 to pass.
In fact, with our carbureted 1984 Jeep Cherokee, I had failed emissions about 1990 and a repair shop looked out the window, said I needed a new carburetor without ever leaving the desk - that was amazing diagnostic skills, they wanted over $400. I opened the Yellow Pages, found an emissions repair shop, guy says he gets me to pass for $25. I go there same day, he inserts a test probe at idle, he pulls off a vacuum hose to lean the carb, then adjusts the screw to bump the idle up to about 1100 rpm, tells me to go get tested, then come back, he'll set for previous/best driveability, take my $25. He doesn't know that I saw/understood exactly what he did, but I did return and pay him. Anyway, I got home, and painted that vacuum hose and carb screw red so I could readily do the "fix" myself for the next test.
OK, other tips. Makes sure the engine is fully warmed up before going to the test. Don't run the AC before the test as that makes the underhood temperatures higher, even though the temperature gauge might still show the same. You need your EGR working/connected most times to pass the NOx test. Most garages have emissions testers, they just don't have the wheel dynamometers to simulate loaded driving conditions. But engines typically run dirtier at idle; in fact for many years, older vehicles were only tested at idle here. And before that, anyting that reached 14 years old was no longer tested. Both my VWs and my 1979 Toyota ruck had been exempt before the state decided those three were causing the state's pollution.