Abstract
The advantages of using electronics to control the engine combustion, are discussed, the electronic spark timing control is described, the efforts by Chrysler, General Motors and Ford and reviewed, and the closed loop feedback control system is described. An electronic spark timing control which is part of Chrysler's Lean Burn system, senses 8 variables before computing the time for spark firing. The variables sensed include amibent air temperature, engine coolant temperature, manifold vacuum, engine speed, throttle position, and rate of change of the throttle position. Speculation has, however, centered on the progressively increasing sophistication of the microprocessor which offers the flexibility of being able to rapidly alter the control system to respond to additional variables or to control additional functions simply by changing the program. A digital microcomputer (MISAR) which controls spark timing is described; it comprises a microprocessor and table of 350 data points. Test runs indicate that MISAR achieves a 9% improvement in fuel economy. Efforts to produce an electronically controlled carburator for closed loop fuel metering, and efforts to demonstrate that electronic engine controls can help meet fuel and emission standards in low-volume applications are briefly discussed.
Published Version
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