Patent ID: 7555928

Claim:
A method of correcting an exhaust flow measurement in a vehicle exhaust measurement system comprising: a) determining a first molecular weight of a make-up gas flowing through a first flow meter; b) determining a second molecular weight of an exhaust gas associated with a fuel, the exhaust gas diluted with the make-up gas producing a diluted exhaust flowing through a second flow meter; c) determining a correction factor based upon the first and second molecular weights, wherein the correction factor generally corresponds to the expression 1 - M ex - M air 2 ⁢ M air ; and d) applying the correction factor to a measurement associated with one of the first and second flow meters, wherein the correction factor generally corresponds to the expression 1 - M ex - M air 2 ⁢ M air , wherein M ex is the second molecular weight and M air is the first molecular weight.