F 150 2WD V8-4.6L VIN W (2007)
Electronic Throttle Actuator: Description and Operation
ELECTRONIC THROTTLE ACTUATOR CONTROL (TAC)
The electronic TAC is a DC motor controlled by the PCM (requires 2 wires). The gear ratio from the motor to the throttle plate shaft is 17:1. There are 2
designs for the TAC, parallel and in-series. The parallel design has the motor under the bore parallel to the plate shaft. The motor housing is integrated
into the main housing. The in-series design has a separate motor housing. Two springs are used; one is used to close the throttle (main spring) and the
other is in a plunger assembly that results in a default angle when no power is applied. The force of the plunger spring is 2 times stronger than the main
spring. The default angle is usually set to result in a top vehicle speed of 48 km/h (30 mph). Typically this throttle angle is 7 to 8 degree from the hard
stop angle. The closed throttle plate hard stop is used to prevent the throttle from binding in the bore (~ 0.75 degree). This hard stop setting is not
adjustable and is set to result in less airflow than the minimum engine airflow required at idle.
