Honda Acura NSX 1991 Service Manual page 243

The idIe speed of the engine is controlled by the Electronic Air Control Valve (EACV).
The valve changes the amount of air bypassing into the intake manifold in response to electric current sent from the ECU.
When the EACV is activated, the valve opens to maintain the proper idle speed.
J
TO MAIN c-
RELAY
SCREW
IDLE
VALVE ;