dumb question......what does the throttle position sensor do?

[ryan roopnarine]

my understanding is that it doesn't actually control engine running, just relays what it "thinks" the throttle wire is doing to the dme. also, that in a modern, non carb'd engine, the throttle plate opens up, the engine "uses" the air, meters the air to anticipate what it wants to happen, monitors the exhaust to see what "actually" happens. im not sure how the tps factors in here.

[winfred]

on your car it varies a voltage to the computer up to around 5 volts, the computer uses this to gauge how far open the plate is, it also has a hand in the tranny's control since it has no cable to refrence throttle opening for line pressure and or shift points, the older motronic cars with the click type units had a wide open switch and a closed switch, it depended on the closed switch to tell it when to turn on the idle circuit and wot to shift from a open to closed loupe (or closed to open, whatever) at full throttle, same general thing is happening with the later cars too