Electronic fuel injection circuit with altitude compensation

Abstract From the Canadian patent

A resistance switching circuit is toggled immediately prior to cranking but subsequent to power application by the output of a manifold absolute pressure sensor effectively responding to ambient atmospheric pressure as indicative of altitude. The switching circuit is connected in series with the resistance element of the potentiometer which serves as the throttle control and alters the transfer characteristic of the control circuit. The gain of the system is such that the output operational amplifier saturates at an intermediate throttle setting such that the response for slow throttle is y=nx over the entire range of manifold pressure while for fast, throttle the response is y=nx for low …