Description

Fig. 75 Transmission controlled spark timing control system.:

NOTE: Refer to Fig. 75 for typical spark timing control systems. Complete system schematics are located in the "Vacuum Hose Routing" section.


This system incorporates a thermal vacuum valve which controls vacuum advance under varying driving conditions to reduce HC and NOx emissions. At temperatures between 59-140°F, the spark timing control system is not actuated. The system is actuated at temperatures below 59°F or above 140°F under normal driving conditions and only slightly actuated under heavy load and high speed driving.