ECM Controlled EVAP System Operation

Introduced on the'95 Avalon for CA, this system is similar to the Non-ECM controlled systems, except that an ECM controlled Vacuum Switching Valve (VSV) is used in place of the Thermo Vacuum Valve (TVV). The VSV is normally closed and duty cycle controlled, which means the ECM rapidly opens and closes the VSV passage to provide precise, variable control of purge flow volume and inhibit operation.

Because this system uses a manifold vacuum purge port, it may provide slight purge flow during idle if conditions can tolerate its enrichment. The ECM uses engine speed, intake air volume, coolant temperature, and oxygen sensor information to control EVAP operation.

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