What is this sensor? I took the car for my teacher to check because the idle was surging and he said that this thing is not creating vacume, so does anyone know how to check it and see if its still good? yes i did check for lose vac hoses and bleed the coolent its circled in yellow

 

Thats the muffler bearing sensor. They do go bad from time to time.

 

Well, I barely see a faint circle around the part with a white dot on it. That is the fast idle valve. It's purpose is to raise the idle when the engine is cold. You can pop the cover off and clean/inspect it if you want. Ask your teacher for details.

While the idle is surging, pinch that big vacuum hose going to the valve closed with a pair of pliers. What happens to the idle?

 

it is the Fast Idle Control Valve - its' only function is to boost the idle in cold weather when the ambient air temperature is below -10C (14F) - otherwise it does nothing

 

fluctuating idle is more than likely caused by the EACV which is the other part on the back of the manifold - just above the one circled - unplug the connector from it and the idle should drop down to about 600rpm and be steady (after you do this you will get CEL and will need to reset the ECU) - if it still surges with connector not plugged in, check to see if you are completely full of coolant - do you have any codes?

 

nope no code btw how do you check for codes and how do i know the eacv is good i had already cleaned the eacv coolent is full, he did say somting about unpluging the wire that conects to the Fast Idle Control Valve but i cant get the wire off.