ISV internal operation question

[Huw Powell]

> CAR: 1985 Coupe GT ISV part number 034 133 455

> QUESTION: To check out my ISV, I pulled it from the 2 hoses, left the 
> key in the "on" position so the ISV was buzzing, and looked inside.  
> The little door on mine only opens up maybe no more than 1/8 of an 
> inch when it's being cycled as the ignotion is on.  I was under the 
> impression that the internal moving part ("door") spun 360° at various 
> rates in a duty cycle type fashion.  

No, it's a sort of rotating solenoid.  That's why it buzzes - each pulse 
opens it, then it (almost) closes with the spring, wait for next pulse.

The pulse length, or duty cycle, determines how much air gets through.

> Also, when trying to move the spinning piece (armature I guess you'd 
> call it...) with the power disconnected, it felt like it was spring 
> loaded to auto return to almost shut when no power is applied to it.  

Exactly.

> I've heard people say to "spin it" with a toothpick, etc... but this 
> one definatly doesn't spin freely... 

They probably just mean to check for free motion by "spinning" it on its 
axis, not actually rotating more than 30-40 degrees, though.

> I flushed the sucker with probably 1/2 of a can of 
> carb cleaner and still does the same thing...

So I take it you have some sort of idle problem?

-- 
Huw Powell

http://www.humanspeakers.com/audi

http://www.humanthoughts.org/