TPS: Throttle Position Sensor
The (TPS) or throttle position sensor indicates the throttle plate angle to the PCM. The PCM uses this, along with other sensor information, to adjust the air-fuel mixture. The TPS contains a potentiometer like the one in the illustration. Note that some TPS sensors are adjusted by loosening two machined screws and rotating the sensor on the throttle body.
This signal is used to indicate normal and sudden acceleration. If it is faulty, a dead spot and hesitation can occur.
A faulty (EGR) or exhaust gas recirculating valve results in stumble if it remains open at idle. It also causes ping and engine knock if the valve remains closed.
The oxygen sensor signal is a vital input for fuel trim in closed loop. It senses the amount of oxygen in the exhaust stream. The PCM uses this input to increase fuel pulse width when oxygen levels are high and decrease pulse width when oxygen levels are low.
The (PCV) or positive crankcase ventilation system keeps the engine’s oil clean by venting crankcase blowby gases into the intake manifold for combustion.