Any suggestions on likely causes? This car has 142,000 miles, it is the 1.1 liter engine, with a carburetor which was rebuilt last year (to pass emissions then!). The limit for HC here in Tennessee is 220, it measured over 700. And yes I did drive it on the highway to attain maximum temperature prior to trying to pass emissions.

 

What were the other pollutant numbers?

Was the test at idle or on a dyno?

Does the car have an oxygen sensor? The later carb models with O2 feedback were incredibly complicated.

 

They have you idle for a while, then they have you step on the gas and measure a couple of times at 2500 RPM. I don't know if the car has an O2 sensor but if it does that's sure worth a try. To make matters worse -- I forgot to mention -- that this is a California emissions compliant Civic. Complicated? You bet, it's got about 20 vacuum lines going into the carburetor! The HC is 729 limit 220. The CO is 0.22 limit 1.2 (OK) and CO2 is 9.36 (no limit / they just report on it). I pulled out a spark plug last night (new plug wires) and it looks good. Thanks for the reply. I'll try to research the O2 sensor business and follow up.