I just moved to Houston, TX from Upstate NY and have never had tailpipe emissions checked on my 1990 IROC. It only has 36,000 miles, but I have done some reasonably decent mods except engine internals, namely port and polished top end, 24# injectors, SLP tri-Y headers, new high flow cats etc. and didn't want to waste time and money if it wouldn't pass. All OEM AIR equipment is in place and functioning.

After reading through the site, and seeing that there were some local Camaro enthusiasts at the Inspector Quick in Pasadena, and it being the perfect 20 minute drive away I figured I'd give it a shot.

I have my own EEPROM programmer/TunerCAT and have been running a very aggresive Spark curve with noticable gains in performance but likely higher emissions.

Therefore, I had 1/2 tank of premium gas, mixed in two bottles of Iso-Heet (The more expensive red bottle) which is IsoPropyl Alcohol hence the name ISO-Heet, and made a chip with the stock spark curve and VE tables but changed the 22.1lb/hr injector to 24.0lb/hr (to match my injector size) and lastly for extra insurancea slitghtly lean 15:1 A/F stoch ratio. I ran it around for 45 mins, recorded the ALDL data in CATS and then ran VEMaster to fine tune the VE tables.

Needless to say the workers at Inspector Quick liked the car (it's showroom) plus couldn't beileve how well it performed. Here's the breakdown:
High Speed Low Speed
HC (ppm) 47 (standard 144) 53 (standard 148)
CO% 0.02 (standard 0.92) 0.07 (standard 0.83)
CO2% 13.9 13.2
O2% 1.5 2.4
NOx (ppm) 326 (standard 1014) 445 (standard 1110)

So I likely would have passed even with my super aggressive spark/VE curve I run for performance, and I attribute that to maintenace, quality injectors, cats, distributor, Crane Ignition, wires and sparkplugs.

So a 3rd gen should be able to pass emissions even super stringent with some TLC.

If you're worried like I was initally try some of the things I mentioned!

Hope this helps!

Oh it was also a blustry 46 degrees for TX, it was fine for me. And let the car warm up nice and good before testing.

 

Excellent job!!!! I may have to talk to you when I get mine put back together LOL

Which cats are you running?

 

Friend of mine in Houston managed to pass the sniffer test with no cats on his Trans Am. He showed me the readouts and sure enough. Although the tests were easier to pass back then. 220 ppm and 1.2% being the HC and CO max limits.

My local emissions tests are a bit more stringent. 86 ppm HC and .55% CO are the limits.

 

One of the keys to passing the sniffer is to get the cat good and hot. Plus, everything has to be healthy, firing on all 8, no misfires, no clogged air filters, all the emissions equipment hooked up and working. With a cool cat, my car fails emissions. If the cat is hot, it passes with room to spare. Hot cat is key.