Ignition Timing Control - Except Civic: Description

The 1975-76 ignition timing control system is controlled by engine coolant temperature and manifold vacuum. Ignition timing is either advanced (retarded on automatic transmission equipped models) to reduce oxides of nitrogen (NOx) and hydrocarbon (HC) emissions. System is made up of ignition solenoid valve, thermo sensor, advance/retard vacuum advance diaphragm, check valve (1976 models only), delay valve, and vacuum hoses.

The 1977-79 ignition timing control system is one of three subsystems of Honda's CVCC system. Combined with the internal distributor centrifugal advance, the ignition timing control system affects the time at which each spark plug fires the air/fuel mixture.

The ignition spark is controlled according to the engine speed, load and coolant temperature. This system is designed to optimize ignition timing during and after engine warm-up to achieve low emission levels, maximum fuel economy and best engine performance.

Although similar in operation, several versions of the ignition timing control system are used on CVCC engine equipped models. For the purpose of this article, the 1977-79 systems will be divided into a Type 1 system or a Type 2 system. See IGNITION TIMING CONTROL SYSTEM APPLICATION  table.