Abstract: Apparatus for indicating fuel per pulse in a pulsed fuel injection system for an internal combustion engine, especially a diesel engine, includes a magnetic piston axially movable in a cylindrical bore in a fuel line to and from a stopped position blocking an inlet. The piston has an outer diameter just smaller than the inner diameter of the bore and is included in a magnetic circuit including an actuating coil having an inductance varying with piston position. Circuitry provides strong electrical current pulse to the coil prior to injection to move the piston to its stopped position and then provides a substantially weaker AC current to the coil while monitoring the voltage and rate of change of voltage thereacross. The rate of change of voltage indicates when piston movement in response to a fuel injection pulse ceases; and the voltage at that point indicates piston position and therefore fuel quantity injected.

Abstract: A fuel limit controller includes a computer supplying a commanded absolute EGR control pressure that is a measure of fuel supplied per diesel engine revolution. An absolute EGR control pressure equal to the commanded absolute pressure is generated from a subatmospheric pressure source and atmospheric air so that the absolute EGR control pressure is limited to atmospheric pressure. Fuel per engine revolution is limited to the value represented by the absolute EGR control pressure so that the fuel limit is automatically compensated for altitude variations. The rate of change in the fuel limit in response to changes in the absolute EGR control pressure is limited to delay increases in fuel to match the time to purge excess exhaust gases from the engine intake manifold.

Abstract: An exhaust gas recirculation control valve is positioned by a diaphragm responsive to the difference between a control pressure and atmospheric pressure. The control pressure is adjusted so that its absolute value is maintained equal to a command which varies with engine operating conditions, whereby exhaust gas recirculation is reduced automatically upon a decrease in atmospheric pressure.

Abstract: An exhaust gas recirculation control assembly senses a throttle position related vacuum signal, an engine speed related pressure, and atmospheric pressure to create a subatmospheric control pressure suitable for actuating a diaphragm operated exhaust gas recirculation control valve.

Abstract: The position of a limit stop member which limits the mechanical position of a fuel metering valve in a diesel engine fuel injection pump is open loop controlled to a position offset from a desired fuel metering valve limit position by an amount in the increased fuel direction that is equal to the maximum possible error in the open loop controlled positional relationship between the limit stop and the fuel metering valve. The position of the fuel metering valve is sensed and compared with the maximum desired metering valve limit and when the fuel metering valve position exceeds the limit position, the position of the limit stop is closed loop adjusted to the maximum fuel metering valve position.