1979 dodge mobile traveler 360cl wont pass emissions

First things first. ALL gasoline fueled vehicles produce CO2 when they are running. Period. Generally, for emissions testing, CO2 content is noted as a %, but, not tested. You probably mean CO, or, carbon monoxide, not carbon dioxide. (CO2) Very different animals.

In order to be helpful, you have to post the actual tested CO content in the exhaust gas to make a meaningful diagnosis. Your failed emissions test results must tell you what that value is. You should also post the maximum allowable CO content in the exhaust gas, usually as a PPM value. (Parts Per Million) It's helpful if you post ALL the test results along with their MAX allowable values. If you don't do that, chances are you are wasting your time in this format.

Chum lee

EDIT: Your test results should look similar to what landyacht318 posted above. I don't know if Utah still does the same but there should be two sets of test results. One at 15 mph (low speed/load) and one at 25 mph. (higher speed/load) California is one of the most restrictive states in the USA. You must pass both low and higher speed tests to pass the test. (at least in California) Utah may vary.

Should be very little "emissions" systems on that vintage to tinker with.

If I remember correctly 1980 was the last year of Cat converter exemptions for gas vehicles exceeding 10K GVWR (my Dad bought a 1980 Ford 1ton pickup with 400CID engine, had no cat converter, 1981 was first year that all needed cats).

However, it was equipped with a SMOG AIR PUMP system.

I suspect your 79 Dodge most likely will or should have a smog air pump.

The smog air pump would add pressurized air into the exhaust system, this would have the effect of thinning out the emissions at the tail pipe.

A malfunction of the pump and or valves, missing /removed pump or no belt to the pump will result in higher than expected "emissions".

You also should have a EGR valve and passages which tends to clog or get stuck.

Others have mentioned carb tuning which also can affect emissions, clogged passages in the carb or incorrect setting will effect the emissions.

Most vehicles of your age, folks have removed and discarded much if not all of the "emission" related stuff, most times it failed or caused poor running conditions and not to mention killing power and mileage.

Sadly, you are on a uphill battle trying to find a old timer who knows a thing or two about proper carb tuning, doesn't take much misadjustment to mess with the emissions.

Quite frankly I am surprised that there is no exemptions for that age of vehicle. At least in PA they simply look under the hood and under the vehicle for known emissions equipment (doesn't need to work, just be in place) that belongs on it for the age in most counties that are not required testing.

To my recollection, all CA vehicles 1976 and newer need to pass smog every two years. Problem is, most places that do smog aren't really mechanics and don't know squat about carburetors. I had a Ford Ranger with 380,000 miles on the engine that I could get to pass smog every 2 years. It was never a "burning oil" issue. It was always related to combustion. That cross over in the manifold may need to be cleaned. The carburetor should either be replaced with a re-man unit from National Fuel Injection(lifetime warranty), or do your own rebuild with some real Berryman's Carb(Amazon)dip..........not the junk environmentally suitable crud they sell in the parts stores. Not sure if Mopar used a version of a Thermactor set up like Ford did. If so, that is good place to look at for sure. One thing is for sure and try to remember this....All vehicles that passed smog once, can pass smog again. There is not a vehicle made that "can't pass smog". You just have to find out what the issue is and correct it.....not always easy, but is always possible.

Just passed California smog test with a 318.

@25mph and 1415rpm
%co2 13.3
%O2 2.5
Hc 83ppm---max allowable 102
CO% 0.09-----------------0.64
NO 118------------------870

The OP said CO2 not CO. Emission tests require CO2 OVER a certain level, not less.

CO is the air/fuel mixture. Need a good carburetor adjustment or better just get a new one.

No exemptions for commercial vehicles.

DATA allows perspective. List HC, CO, and NOX data. it will have max/min + your numbers listed. One such example a VACUUM LEAK will raise CO numbers. Can we see some numbers, please?

1984 was the first year for mandatory use of converters, prior to that it was optional but if the vehicle came with one it is required. Test on vehicles are a little schety to beging with.

A cat actually makes C02.

Check and see if you can get a vintage vehicle exemption at that age you just might.

Common problem with 360 is the exhaust cross over passage in the intake manifold. Ackward job to clean without taking manifold off.
Odd that the vehicle needs emission testing!

when we had emissions testing here on my camper van i had to adjust my idle mixture screws on the carburetor in until the engine just started to stumble at idle a bit to get it to pass. there was a one year exemption issued if it would not pass after several tries to give you time to get it fixed.