Higher-than-normal CO emission levels may be the result of which of the following? A. An ignition misfire, a lean misfire, or a mechanical misfire B. An overly rich air/fuel ratio C. High combustion...

Higher-than-normal CO emission levels may be the result of which of the following?

A. An ignition misfire, a lean misfire, or a mechanical misfire

B. An overly rich air/fuel ratio

C. High combustion chamber temperatures

D. Both A and B

Higher-than-normal NO_x
emission levels may be the result of which of the following?

A. An ignition misfire, a lean misfire, or a mechanical misfire

B. An engine that is slightly overheated

C. High combustion chamber temperatures

D. Both B and C