The solenoid valve is closed at rest. It authorises the passage of oil to control the phase shifter in line with the operation of the engine: -
if the engine speed is between 1,800 and 6,500 rpm, - if the throttle potentiometer is not at no-load NOTE: if the solenoid valve is jammed in the open position this will result in an unstable idle and the pressure in the manifold at idle will be too high. This affects the mechanical timing of your inlet valves and the other mechanical components: pistons/exhaust valves. The result will affect the volumetric efficiency of the engine, hence a change to the fuel and ignition maps. The solenoid only opens or closes as detailed above and it is not continuously variable.
if the engine speed is between 1,800 and 6,500 rpm, - if the throttle potentiometer is not at no-load NOTE: if the solenoid valve is jammed in the open position this will result in an unstable idle and the pressure in the manifold at idle will be too high. This affects the mechanical timing of your inlet valves and the other mechanical components: pistons/exhaust valves. The result will affect the volumetric efficiency of the engine, hence a change to the fuel and ignition maps. The solenoid only opens or closes as detailed above and it is not continuously variable.