Ford ISC-BPA

[Chad Clendening]

Dave Williams wrote:

>  How does the Ford idle air valve work?
>

Yep, PWM it.  Set the frequency high enough to not pulsate the thing.  200
Hz should be fine.

Basically you want to increase the pulse width when you want it to speed up
and decrease the PW when you want it to slow down.  I don't know which way
it operates -  if it bypasses more air when alot of PW is present or when
none is present so you may have to reverse the PW correction.  Slowly change
the PW and see what the engine speed does.

Chad

>  From the initial descriptions I found, it was a solenoid, pulsed
> rapidly to shuttle the valve open and closed to meter air.  Now I've
> found some descriptions that make it sounds like it's fed a pulsewidth
> modulated signal that varies the voltage, pulling the solenoid only
> partly open as needed to meter air.
>
>  Using it like a shuttle valve would be easier in software; using it pwm
> would be harder since you could never know exactly how much air the
> valve was passing, since there would be no feedback from the solenoid's
> position.