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1976 Chevrolet Camaro Failed Smog Check

My 1976 Chevrolet Camaro failed smog test due to HC 2424/2502, CO 0.13/0.13, and NO 1328/1115. What is needed to be repaired on my vehicle? Please help me.

Answer:

There are several factors to take into consider with high HC and NO numbers like these. You'll want to make sure your Chevy Camaro is distributing fuel evenly to all cylinders and in the proper amount to create 14.7:1 air to fuel ratio. Anything leaner will cause increased NO and when lean enough, increased HC as well. HC amounts above 500ppm almost always indicate a cylinder(s) which is completely misfiring due to a lean fuel condition. Not enough fuel is getting to the combustion chambers. You also want to make sure your Camaro's EGR valve (system) is working in order. The EGR valve, when opened, recycles some of the spent exhaust gas back into the combustion chambers. On a vehicle with correct air to fuel ratio the exhaust gas being sent back to the combustion chambers should be fairly spent and almost inert. This causes the engine combustion temperature to lower and reduces NO production. Finally, an engine compression test. A smog check repair station may want to perform this test first in order to get a general idea of your Chevy Camaro's overall engine condition. Because NO is created when engine temperatures exceed 2500f and high engine compression is capable of producing these temperatures, an engine compression test will show whether the high NO fault is in part or in whole is due to high compression; and in one or more cylinders or all. posted by SmogTips Support

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