Testing ICV - already know the basics

[dmmmmd]

Hello everyone,

Like many others, idles rough and sometimes bouncy. Cleaned the ICV as many suggested and it'll be okay for a little while but eventually return to rough idle. And I'm suspecting a faulty ICV. Here's what I've tested so far:

- the ICV vibrates and hums when powered on
- resistance to spec per Bentley --- 20 and 40 ohm across terminals
- removed ICV from hoses and connect to 12V and it snaps shut
- but when I remove the voltage, it stays shut

So my questions are:
- should the ICV opens up once disconnected from the 12V?
- given the first 3 points above, definitive enough to say that the ICV is not faulty?
- what exactly causes the ICV to open up? When gas is applied?

Thanks in advance!!!

[nando]

the ICV has two windings with opposite polarity - it works on a PWM signal at ~99hz (I don't remember exactly, it might be 60 or 90, but regardless - it works on PWM). An increasing duty cycle on one side and decreasing duty cycle on the other will open, and then the opposite to close. It will not just open or close based on 12v (well, it will, depending on which side you hook up - but you're basically running it at 100% DC).

If I remember right something like 20% duty cycle is fully closed, and 70% duty cycle is fully open.