DESCRIPTION & OPERATION
This system controls the air/fuel mixture in response to warm up condition. The Vacuum Control Valve (VCV) and Vacuum Switching Valve (VSV) control air/fuel ratio. When valve is closed, a rich mixture is created. When valve is open, a lean mixture is created.
VACUUM CONTROL VALVE (VCV)
Remove VCV valve. (Scheme 86) Using a vacuum pump, apply 12 in. Hg vacuum to port "S". (Scheme 87) Blow air into port "Y" and ensure VCV opens. Release vacuum. Blow air into port "Y" and ensure VCV closes. If valve fails to operate as specified, it must be replaced.
Scheme 86
Scheme 87
Scheme 88
VACUUM SWITCHING VALVE (VSV)
- Connect VSV terminals to battery terminals. (Scheme 88) Blow into port and ensure VSV is open. Disconnect positive battery terminal. Blow into port and ensure VSV is closed. If valve fails to operate as specified, it must be replaced.
- Using an ohmmeter, ensure no continuity is present between VSV positive terminal and VSV body. If continuity is present, VSV must be replaced.
- Using an ohmmeter, measure resistance between positive terminal and other terminals. Resistance should be 38-44 ohms at 68°F (20°C). If resistance is not within specification, VSV valve must be replaced.