79 with rebuilt 350/350 turbo and edlebrock manifold/carb. i'm trying to pass California smog emission test with no luck- no way will i sell my car to the state for 500 bucks. my first attempt i passed all the emission sections except for CO2 which was high especial at low speeds. i'm going to change the oil/replace the plugs and wires/ and lean the carb way out tomorrow before going back but someone suggested i change out the o2 sensor. where would i find this (in front of the cat?) and where does the wire plug into? any help would be greatly appreciated- i've found tons of great info here and want to thank you guys for keeping this going.

u have a 79? its not computer controlled and doesnt have a Oxygen sensor. High CO2 levels indicated a lean burn, richen it up a little and change ur fuel filter. I belive this is correct to my understanding....Sure if im wrong someone will correct me!

-Anduh

First of all, you don't have an oxygen sensor in your 79. Secondly, high CO2 readings indicate efficient combustion . Are you sure it flunked because of high CO2 readings or did it flunk because of high O2 readings? A high O2 reading indicates a lean air/fuel ratio.

yes, you are correct, i do not have an o2 sensor- i had read that california sarted putting them in GM midsized cars beginning in 79 then all cars after80. so i thought i might have one of them.:oops:
i failed because of high CO (i added a 2 after that before- sorry for the misinformation) not CO2.
CO2 measured 9
O2 measured 7
CO measured almost double the max
HC and NO measured below average
would adding a o2 sensor now be worth it to help test?
hope this is clear enough and thanks for the responses.

... i failed because of high CO... would adding a o2 sensor now be worth it to help test?
High CO is caused by a rich air/fuel mixture. Try leaning out the carb like you stated in your initial post. Check the plugs and wires. Make sure all of your plugs are firing properly so you're not blowing unburned fuel into the exhaust. Don't bother with adding the oxygen sensor.

high CO2 readings indicate efficient combustion

In one of my emission books, it talks about exsessive CO2 readings actually being bad...even tho it is a non toxic gas, it does harm the invirement in ways...But ONLY excessive amounts...Kinda odd. Damn i was wrong tho....Back to the books!

-Anduh

high CO2 means that there is not a bad thing. From what I understand if the vehicle is to rich you will have high CO levels and if the vehicle is to lean you will have NO. I am not sure how installing an O2 sensor would help you on a non computer controled car (besides the fact I don't know how you would wire it to). I would recomend taking the car to a shop with a gas analizer and having them adjust the carb untill the levels are right. Also make sure you drive around long enough (15 min) to get that cat good and hot so it can do it's job. Good luck with this

On another note does california not exempt cars after 25 years? I don't know what I would do here if my car wasn't age exempt.

I'm sorry for the poor gramer, I was trying to say in that first line that CO2 is the sign of complete combustion. From chem class you may remember that H(something)C(something) + O2 -> H2O + CO2 + HEAT. There are some other things in with that hydrocarbon that will combine with oxygen if to much is present and if there is not enough oxygen then some carbons will only get one oxygen. I'm sorry for the double post, I hope this helps