Throttle Positioner System: Description

The throttle positioner (TP) system controls exhaust emissions during deceleration by holding the throttle plate at an above-idle position during "OFF"-throttle operation. This prevents the fuel mixture from being starved of air and helps control HC and CO emissions. The controlling unit is a throttle positioner (TP) diaphragm which is vacuum operated.

The system consists of a throttle positioner diaphragm, a vacuum transmitting valve (VTV), and a thermostatic vacuum switching valve (TVSV).