QuestionI have 1991, Mits galant EFI/FI engine which failed emission test. I asked a question about this earlier it is just follow up to that.
Is throtlle position sensor same of Oxygen sensor ? What is the difference between these two ?
AnswerSiva,
The Throttle Position Sensor (TPS) and the Oxygen (O2) sensor are different and they have two quite different functions. The only thing that makes them similar is that they are both part of your emmisions regulation system.
The TPS is in place to send data to your car's computer (ECU). The data it sends tells the ECU the current angle of the throttle plate. When the throttle plate is fully closed, that means your foot is not on the gas pedal at all. Your car is then idling. When the ECU knows the car is idling, it sends less fuel to the engine, and it requires less air to enter engine as well. Conversely, when your car is at Wide Open Throttle (WOT), that means you are under acceleration or travelling at highway speeds.
The Oxygen Sensor is part of the emissions control system and feeds data to the ECU. The goal of the sensor is to help the engine run as efficiently as possible and also to produce as few emissions as possible. The oxygen sensor is positioned in the exhaust pipe and can detect rich and lean mixtures. The mechanism in most sensors involves a chemical reaction that generates a voltage (see the patents below for details). The engine's computer looks at the voltage to determine if the mixture is rich (too much gasoline) or lean (not enough gasoline), and adjusts the amount of fuel entering the engine accordingly.
If your TPS fails, your car will not idle properly, may not accelerate, and may not allow your car to be started. When the oxygen sensor fails, the computer can no longer sense the air/fuel ratio, so it ends up guessing. Your car performs poorly and uses more fuel than it needs to.
I hope that answered your questions.
