ISV Question - One More Time

Huw Powell audi at
Tue Nov 6 13:24:31 EST 2001

> I'm not quite sure about your ISV. There are basically two
> different versions: one that is totally closed when no power
> is applied and one that is a little bit open when no power is
> applied but closes completely when the ECU applies current
> "backwards"...

exactly true

> So: When you invert  + and - while tesing with the 9V Battery,
> does the plunger (?) move in the opposite direction (not
> sure what you mean with "rotate") and close the gap?

the "plunger," at least on some of them, is curved, rotating thing.  it
doesn't rotate 360 degrees, just back and forth.

> You should be able to close the ISV completely I guess, either
> by applying no power or inverted power. If not, the thing is
> knackered or dirty.

I think the partially open ones tend to go all the way shut on the
return from all the way open, and the amount of air they pass is
relative to the duty cycle of this process.  The "small opening" is kind
of a "limp home" idle bleed... again, just my partially worked out

Huw Powell

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