ok im in the process of doin a b2 to b7 swap in my 91 civic. i pulled the b2 out and set them beside eachother so i could swap all my stuff over to the b7. well i noticed in the back(or side, whichever u wanna call it) below the intake are 2 sensors, one is the oil pressure sensor..already knew that, and beside the oil pressure sensor is another sensor..its a rather big sensor. i looked on the b7 and its got a plug in its place??anyone know what im talkin about??sorry i cant get pics, the motor is across town.

 

does it look like 2 prongs on it? perhaps you are referring to the temp fan switch (i think thats what its called)