Exhaust gas analyzing system

An exhaust gas analyzing system, comprising:

• a sampling flow path connected to an exhaust gas flow path through which gas exhausted from an engine flows to sample a portion of said exhaust gas;
• a dilution gas flow path connected in parallel to said sampling flow path, said dilution gas flow path diluting said sampled exhaust gas with a dilution gas to form a diluted exhaust gas;
• a sample bag storing a portion of said diluted exhaust gas;
• a gas analyzing portion analyzing said diluted exhaust gas in said sample bag;
• wherein flow rate of said exhaust gas is measured;
• and
• a trace gas with a known concentration introduced into said exhaust flow path while monitoring flow rate of said trace gas, said trace gas introduced into said exhaust flow, path upstream from a first connecting point, said first connecting point connecting said exhaust gas flow path to said sampling flow path, said trace gas forming diluted trace gas when mixed with said diluted exhaust gas and said dilution gas, said diluted trace gas analyzed in said gas analyzing portion;
• wherein total mass of said trace gas calculated from a result of said analysis in said gas analyzing portion is compared with total mass of said introduced trace gas to evaluate said analysis of said diluted trace gas in said gas analyzing portion.