TABLE OF CONTENTS Engine control in the vast majority of engines means regulating fuel and air intake as well as spark timing to achieve desired performance in the form of torque or power output. Until the late 1960s, control of the engine output torque and RPM was accomplished through some combination of mechanical, pneumatic, or hydraulic systems. Then, in the 1970s, electronic control systems were introduced.
This chapter is intended to explain, in general terms, the theory of electronic control of the automotive engine. Chapter 7 explains practical control methods and systems. The examples used to explain the major developments and principles of electronic control have been culled from the techniques used by various manufacturers and are not necessarily representative of any single automobile manufacturer at the highest level of detail.
The motivation for electronic engine control came in part from two government requirements. The first came about as a result of legislation to regulate automobile exhaust emissions under the authority of the Environmental Protection Agency (EPA). The second was a thrust to improve the national average fuel economy by government regulation.
The combustion of gasoline in an engine results in exhaust gases including CO 2, H 2O, CO, oxides of nitrogen, and various hydrocarbons.
The engine exhaust consists of the products of combustion of the air and gasoline mixture. Gasoline is a mixture of chemical compounds that are called hydrocarbons. This name is derived from the chemical formation of the various gasoline...
