A malfunction associated with loss of idle speed is mainly associated with a failure of the idle speed control valve
But this malfunction may also be associated with air leakage through loose connections of the throttle body hoses.
The idle speed control valve can only be removed after dismantling the throttle body.
After unscrewing the fastening nuts, remove the throttle body from the receiver studs without disconnecting the coolant, adsorber and crankcase ventilation hoses from it (see Replacing the throttle assembly of the Niva Chevrolet).
Disconnect from the idle speed control valve connector wiring block
Use a Phillips screwdriver to unscrew the two screws securing the regulator to the throttle body.
Remove the idle speed control valve
Remove the rubber sealing ring from the hole in the throttle body
Before installing a new regulator, use a caliper to check the distance between the end of the valve needle and the supporting surface of the flange.
The distance should be no more than 23 mm.
This is necessary in order not to damage the valve during installation – the valve needle should not rest against the seat of the throttle body.
Do not purchase a control with a needle protrusion greater than 23 mm.
Before installing the control, clean the valve seat, air channel and surface under the control seal ring in the throttle body.
Put the seal ring on the cylindrical surface of the control.
Apply engine oil to the seal ring.
Install the idle speed control in the reverse order.
Tightening torque of the control screws is 3–4 Nm.