Throttle Position Sensor 1990 5S-FE

[Bossard]

I am having an RPM problem with my Celica. The RPM's run up and down from about 1300 to 2200 and then drop to about 1800 and stay there pretty much without my foot on the accelerator after the engine is warmed up while driving. I did the obvious and disconnected the throttle position sensor and the engine ran normally when I took the car out for a test drive. My question is why does the engine run normally without the sensor connected? Doesn't the sensor always control the throttle position? Also, if the sensor is bad wouldn't the engine check light come on?

[supraturbo88]

hey man, i am having a similar problem. i dont know exactly what it is but its happening. i just put a 2.2L back into my 92 gt. i was tired of looking at it sit at the shop i work at. well today is the first road test for it. been dealing with leaks and what not. it was idling at 2000-2200 rpm so i starting playing with the vacuum hoses, switching them around trying to get the best outcome. and my throttle position sensor may have a problem. fuel filter was leaking at the top end and the first time i cranked it up it caught fire and scorched some wires and sensors. they all seems to still be working but im not for sure. i got the idle down to around 1000-1200 rpm by playing around with things