MISAR-The Microprocessor Controlled Ignition System

Marking an automotive milestone, microcomputer control has been introduced to a production automobile. The MISAR Ignition System is standard equipment on the 1977 Oldsmobile Toronado which is the first production automobile ever to be equipped with an electronic digital microprocessor. This technological development is the first step toward the use of a programmable digital computer to manage complex vehicle and engine control functions and provide a new dimension of driver convenience.

This paper explains the significance of ignition spark timing in internal combustion engines and describes how the MISAR System provides almost infinite advance curve flexibility to meet the requirements for fuel economy, engine performance and exhaust emissions. The hardware components of the system are described including the microprocessor and the various engine sensors. Finally, a brief operational description shows how the system functions to compute and execute the desired ignition commands.