Aircare changes their frikken minds all the time. The last I've heard they're not checking idle speeds. The cash grab is just getting riduculous. C02 is an idication of engines efficiency. On a stock engine the driving test is the least to worry about. At idle was the C02 low?
on a carbureted motor with NO Catalytic your looking at aprox 12%. I dont know your engines specs but if you go too lean you'll have a lean misfire and you'll have too much HC's. CO is a byproduct of combustion and indicates if your too lean or rich. Whatcha at??? 2% CO at idle??? 1%?? if your at 5% or more your C02 can be low due to running too rich. A stock engine with stock carbs should pass without any issue and should be a snap.
Since you failed on C02 I'm assuming your just simply a tad too rich. You can lean out the a/f mixture and back the timing aprox 5 degrees. Too retarded your engine will run hot and your oxides of nitrogen will go up. Unlikely but sometimes if you freshened up your heads and got a valve job the valves needs some mileage for better sealing. Theoretically not so true but I've seen it before. Also the new rings will have blowby too which may effect emissions.
I've heard people using higher octane assuming it helps but I honestly haven't seen much different results in all my year of doing aircare.
If your c02 is too high thats a simple problem to fix. If you had high HC thats a little more complicated.
You wanna know the truth about Aircare repair shops. They look at old beetles as a waste of time. Aircare looks at AirCare repair shops with a points system. If a licensed aircare mechanic has alot of failures (high percentage failing when they're suppose to pass) Aircare mandates that the techincian that supposedly \"passes\" the car (which fails) takes another \"written examination\". Of coarse an aricare tech doesn't want an old car potentially flakey car. Old cars like ours have a tendancy to be intermintent or \"flakey\" so if the car looks like it'll pass on the 4 or 5 gas analyser but fails alot of aircare technicians are reluctant to take on jobs like that. Also theres a $$$ limit that Aircare give a car owner depending on year of vehicle. Alot of mechanics dont want to learn or familiarize themselves with old beetle technology. Shops looks at the flat 4 as an ODD engine. Many are not familiar with the solex carb. Duals scares the crap out of them 'cause alot of them WONT have jets to play with and also they're probably not familiar. I've fiddle on alot of ACVW's and I absolutely hated working on alot of them because of the unmaintained disrepair stuff out there. I\"m being honest and if your at a shop bottom line is completing jobs successfully without comebacks. I am no longer working in that field even though I'm a licensed mechanic I can see how alot of aircare shops out there are scared to touch our cars. Almost 99.9% of the aircare repair shops DO NOT have dynos. Engines react completely different with or without loads. Idle is the only real thing a mechanic can test on the gas analyser. Since our engines expands the idle may effectively go up typically. that will also effect the emission output.
I'm not disrespecting anyone here. I'm merely stating things that many people are not aware of. I've had cars failing and the owners expect miracles with cars that have had no tuneups in 3+ years or worn out carbs, distributors etc etc.
Your heat exchangers will not effect anything as long as they're going on a stock motor or slightly larger.
If your idle was low just by bumping up the idle will increase the C02 readings. spec sheet would help greatly. minimal info doesn't show the big picture.
I know alot of mechanics that know squat about carburetors. Yes in apprenticeship at BCIT I learned basic function of a carb but I've learned alot on my own through the years. Majority of new licensed mechanics are more in tune with electronics not carbs. Even many late 30yrs old - 40 mechanics do not know the clockworks of carburetors.
