there is a sensor that is located on the front, bottom half of my intake manifold. it is right above the fuel rail and have a plug that comes off the harness into it. there are two vaccuum lines going into either end. the sensor itself is made by denso....anyone have a clue what i am looking at??? the plug is missing and it wont start. i have compression in all four cylinders but it still wont start...anyone know what this thing is and if its my problem???

 

I think you're talking about your EGR valve, black top.
be sure to mention year, make and model.