Failed Smog Test

carringb wrote:

Dakzuki wrote:
If the HC is too high you are too lean. High CO is too rich. You may have an intake leak causing the lean condition. Check for bad vacuum hoses and anything that was disconnected. I presume the vehicle wasn't hooked up to a sniffer after the carb was put back. It should have been to at least validate the idle mixture.

High HydroCarbons is unburned fuel meaning too rich. CO means incomplete combustion, which could be form many reasons. Too lean shoots the NOx up.

I used to do this for a living back in the day before OBD and much in the way of EFI. You can put a car on a sniffer and watch the results as you tweak the mixture. Lean out the idle, and HC goes up as CO goes down. Unscrew the jet and watch the opposite. Intake leaks will lean the mixture and raise HC.