When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Hi folks. I live in an area of Colorado that requires a smog test to register my Z28. I’ve failed 3 times at this point.
The engine is a 383ci iron block built by Thompson Motorsports in Texas. Specs:
-Trick Flow 225ci heads
-Forged internals
-Custom 232/238 @ 112 cam, .6296/.6295” lift
-Ported FAST intake with 100mm-102mm TB, MAF, and air filter box
-Stainless long tubes with cats, y-pipe and dual exhaust
That cam is doing you no favors.
A vicious idle lope will have it puking unburned gas like the hydrocarbon levels indicate (the first was best there, BTW).
Maybe raising the idle until it smooths out some might clean that up some.
A cam that size is not going to pass a tailpipe sniffer. Leaning out your fuel would reduce hydrocarbons, but jack up oxides of nitrogen. This problem could be reduced some by running e85, but probably not enough to come close to passing, and I have no idea what this would do to CO numbers.
Have a friend in a part of Colorado that doesn't have emission testing register the car for you. Of course, I know NOONE who has ever done that.
Looking the Colorado gov site, I also see this:Waivers. The state Division of Motor Vehicles can issue waivers for the emissions test requirement in three circumstances:
repair waivers: 1968 or newer vehicles with $715 in emissions‑related repairs and 1967 or older vehicles with $75 in emissions‑related repairs;
economic hardship waivers: if a vehicle has failed at least one emissions test, no repairs are necessary, and the owner is receiving need‑based financial assistance; and
RapidScreen. RapidScreen is the mobile emissions testing program in Colorado. Instead of testing a vehicle at an emission testing location, owners drive by a mobile testing unit. Vehicles must drive by a testing unit and receive two clean readings at least 60 days prior to a vehicle's registration renewal month. If the vehicle passed inspection, owners will receive notification on their next renewal registration statement. Motor vehicle owners simply pay the emission testing fee during their registration renewal. RapidScreen unit locations can be found here.
I'm sure you could get an estimate to rebuild your engine to pass emissions and it would be much more than $715.
Or perhaps you could pass a drive-by test.
A real sucky solution that I know a few members in California do is to swap engines every two years to pass the emission test. So basically install a stock JY engine to pass the test and then back to the real engine.
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Slideshow: From wobbling harmonic balancers to failed EBCMs, these are the issues that define long-term C5 ownership and what repairs typically involve.
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Slideshow: A modern Camaro transformed into a retro icon, this limited-run "Bandit" build blends nostalgia with brute force in a way few revivals manage.
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Slideshow: Cadillac didn't just crash the high-performance luxury vehicle party, it showed up loud, supercharged, and occasionally a little unhinged...
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Slideshow: A one-off sports car that looks like a vintage Italian exotic-but hides a C6 Corvette underneath-just sold for the price of a new mid-engine Corvette.
Need help passing emission test! 
