5 - The Basics of Electronic Engine Control

Abstract

This chapter explains the theory of electronic control of the automotive engine. It also explains that an automotive engine control has both open- and closed-loop operating modes. A closed-loop control system requires measurements of certain output variables that tell the controller the state of the system being controlled, whereas an open-loop system does not. This chapter discusses the various electronic engine control functions separately and explains how each function is implemented by a separate control system. Some of the important engine variables discussed here are mass air flow, fuel flow rate, spark timing, power, and intake manifold pressure. New regulations for emissions have continued to evolve and encompass more and more vehicle classes. Present-day regulations affect not only passenger cars but also light utility vehicles and both heavy- and light-duty trucks. Engines using mechanical, hydraulic, or pneumatic controls cannot meet government regulations, but engines using electronic engine controls can. The configuration and control for an automotive engine control system are determined in part by the set of sensors that is available to measure the variables.