 Where multiple carburetors are used the mechanical linkage of their throttles must be properly synchronized for smooth engine running and consistent fuel/air mixtures to each cylinder.In the 1980s, many American-market vehicles used "feedback" carburetors that dynamically adjusted the fuel/air mixture in response to signals from an exhaust gas oxygen sensor to provide a stoichiometric ratio to enable the optimal function of the catalytic converter.Feedback carburetors were mainly used because they were less expensive than fuel injection systems; they worked well enough to meet 1980s emissions requirements and were based on existing carburetor designs.