Throttle Position Sensor: Description and Operation

PURPOSE
The throttle potentiometer indicates throttle position to the ECM. By monitoring this input, the ECM makes air/fuel ratio adjustments based on whether the engine is accelerating (richer, throttle open) or decelerating (leaner, throttle closed).

OPERATION
When the throttle is opened quickly, all injectors are simultaneously energized for one pulse. Duration of this extra pulse is modified by engine temperature; i.e., longer with a cold engine.

Increasing the duration of normal injection pulses is done in proportion to the rate of throttle opening. Added duration ceases in a short time when throttle movement stops. Engine temperature is also a variable factored in by the ECM in calculating pulse width.

Fuel cut-off is controlled by the throttle potentiometer. Conditions under which cut-off occurs (such as deceleration) are programmed into the ECM.

Throttle Potentiometer:

LOCATION
On throttle linkage bellcrank at center rear of engine.