Abstract: A remote gas analyzer for motor vehicle exhaust emission surveillance in which a planar array of gas analyzer beams intersects substantially an entire cross-sectional segment of an exhaust gas plume in order to determine the volume concentration of gas pollutants in the exhaust. In a further variation using more readily available equipment to detect the less prevalent pollutants, the planar array determines the change in amount per unit volume of a first pollutant emitted by a motor vehicle passing the array. The first pollutant having a relatively high and more easily detectable concentration. A second, multi-spectral gas analyzer beam intersects the exhaust to determine the change in concentration of the less prevalent pollutants with respect to ambient, and also determines the change in concentration of the first pollutant.

Abstract: An electronic system which limits exhaust emissions from an automobile engine by selectively retarding the point of firing the spark plugs at selected speeds during acceleration and at different speeds during deceleration; said system including a capacitive discharge ignition system which is responsive to an electronic system which will retard the point of firing the spark plugs a predetermined amount dependent upon the speed of the vehicle as above or below a predetermined speed. Said system also including an improved low cost tachometer for feeding to the system an analog output dependent upon the engine speed, which analog output is fed to a low rpm control level detector and a high rpm control level detector, and the outputs of said detectors are fed to a control logic which is connected to the vacuum advance of the engine to selectively disconnect the vacuum advance of the engine at certain speeds.