the one closest to the throttle body that the coolent hoses run to is eacv or iacv(ive heard it called both)but the other on with the big vac hose running to it is the fast idle control solenoid valve*(on the lower right of the intake man. looking from the front of the car) ,atleast thats the way it is in the 89 civic service manual

 

why doesnt my 88 si have this? and im assuming this thing is for warm up higher idle right? mine idle's at 2k when cold.. ?

 

coolent temp below 14 deg. far.,and engine speed below 1800 is when it increases the airflow

 

so what does my 88 SI do then? it has a cold idle of 2k like normal..?

 

that would have to do with the eacv,it dosent come out and say anywhere ive read how that thing works but im guessing the coolent running threw it like makes it heat up that rubber covered spring looknig thing in thier and makes it close off the air opening when the engine gets hot.and then when u turn on the lights or the heater motor the ecu sends a signal to it and opens it up to let tthe engine idle up a little?