Idle Valve Setup

[tfalling]

I am working on setting up idle control. I have a 5.0 SBF that I will be using a Ford style 2 wire (I assume a PWM) IAC Valve. In testing the valve, I noticed that the valve makes a rather loud noise based on the frequency of the output I have set. Is this normal??? I am using the MS3x idle pin with the diode in the loam. I assumed that these type of valve operated as such that the higher the duty cycle the more (or less depending on settings) the valve would hold open. I really don't know, but I am looking for a good explanation of, the theory of operation for this type of valve. How does the output frequency play into the operation of the valve.

TJ

[elaw]

You should find that the problem lessens as you increase the frequency driving the valve. I've got mine set at 1021 Hz for that reason.

[tfalling]

The noise become much more tolerable in the higher frequency ranges.... currently have it set at 306Hz and its just a little hum. So how could I determine the best frequency to use?? Also, shouldn't I see the valve go from all the way open, to all the way closed (or visa-verse depending on the inverted/standard setting) when testing it if I go from 0% to 100%. My valve doesn't seem to move more then a 1/10 of an inch in total.

[arran]

I selected the lowest frequency that allowed the valve to work and was quiet. For my Mazda this was 204 Hz.

To check that it is working I used the Megasquirt test mode and an air compressor. The airflow isn't an exact science, steadily increase the duty and observe that the air the valve passes goes from nothing up to an open pipe