High CO during inspection


I have a 86 Pontiac Fiero V6 with a 4 speed. It failed inspection due to high CO readings. How can I fix this?




Excessive CO happens when incomplete combustion of fuel takes place. That can be caused by old, weak spark plugs, or possibly an injector/carb problem. On the outside, it might even be a cat converter problem. Did anything else read high or very close to high?


One of the best things one can do BEFORE an emissions test, is to change the spark plugs (and spark plug wires if they have been in several years), air filter, and pcv valve. YOU can do these things now, and, maybe, pass the emissions test. If not, there are places which specialize in repairing cars to pass emissions test.


High CO is running rich, not mis-fire. Is this “classic” carburetted (good luck) or fuel injected??


Here is a link that might help. The link has info for both carburetor and fuel injected engines.


With fuel injection, a worn out/bad O2 sensor can cause high CO reading. I had multi-point fuel injection on the 2.8 V6 in my 88 Beretta, but I don’t know about 86 model years. This engine was offered with carburetors, TBI, and multi-point fuel injection over the years.

Ed B.