Throttle Position (TP) Sensor
TP sensor is a rotary potentiometer. TP sensor monitors throttle plate opening. Its signal to the PCM is proportional to throttle plate opening angle and rate of angle change. The TP sensor signal affects air/fuel ratio, injector timing, idle speed, EGR flow and ignition timing. The TP sensor is mounted on throttle body, at throttle plate rod.
Mass Airflow (MAF) Sensor
MAF sensor uses a hot wire sensing element to measure amount of air entering the engine. Air passing over the hot wire causes it to cool. The hot wire is maintained at 392 F (200 C) above ambient temperature, as measure by a constant cold wire.
The current required to maintain hot wire operating temperature is proportional to the intake air mass. The PCM calculates the fuel injector pulse width in order to provide the desired air/fuel ratio.
Friday, February 20th, 2009 AT 7:41 AM