Wastegate solenoid rapid clicking

[86GN-862+2]

Ok, trying to understand the solenoid's function in controlling boost. I can understand it is an open/close air valve which is electrically controlled by either the computer or an electronic boost controller. In doing so, it clicks when it opens and when it closes the port for the air signal which makes its way to the wastegate. I thought this solenoid was either on or off according to the boost signal it was set for. I have found it actually clicks rapidly while in operation. It sort of confuses me how it operates this way while building boost. I though it would remain closed until desired boost was reached. I also thought that once that boost setting was met, it would vent excess air(boost signal) to maintain such boost settings in a simple on/off fashion. Please clarify for me how this works. Using a Trust Profec Spec B I to control the GM solenoid. Thanks in advance for any expert replies to this thread!

 

[22lbChevelle]

Research PWM (Pulse Width Modulating).

Basically, if you turn a lightbulb on and off faster and faster, it will look brighter and brighter right? Up until the point where you have it on all the time and then the brightness is maxed out.

If you open a garden hose on and off, faster and faster, it will flow more over a period of time.



Well, PWM works the same way, except you arent turning the solenoid on and off faster, you are turning it on and off for longer periods, but at the same frequency. So you turn it off and on at 49 Hz (49 times a second), and to change the effective "on" value, you vary the time each pulse is on. Hence, you are varying the pulse width. Pulse Width Modulation.

 

[86GN-862+2]

Getting it…
Could you go a bit into why we get boost spikes with an EBC? Fine tuning the sensibility of the controller fixes that problem but lag may be present when "de-sensitized". Thanks again. Jr.