Re: high-pitched...frequency valve

[Oliver Seiler <oseiler@acm.org>]

On Tue, 11 Jan 2000, Oliver Seiler wrote:

> [...]
> 
> Not much more information beyond that. The electromechanical nature of it
> makes me think it could go bad, but there isn't anything on what would
> happen if it does. I also can't tell if it's serviceable. And I still
> don't know if the noise is normal. If it's inside the fuel distributor,
> the only thing to do would be to get a new one, I would think (assuming
> it's not working properly).

Found a few interesting links which describe the frequency valve in more
detail. It's surprising that I don't find a mention of this in Bentley's.
I guess the question is whether it actually exists or not in the Scirocco
CIS system (with Lambda). I'll have to actually find it, since it seems to
exist outside of the fuel distributor itself.

Links:

http://www.ncr-pca.org/cis.htm (looks relevant to Scirocco)
http://www.teleport.com/~scottmo/boost.html (Audi CIS)
http://24.5.5.58/a2-idle_problems.txt ('84 GTI related)

Not much else. The last link mentions that the procedure for changing the
duty cycle on the frequency valve is described in "Raven's book" (I assume
he means Water-Cooled VW Performance Handbook). Unfortunately I can't find
a reference to the frequency valve there, although the procedure for
modifying the idle mixture using the Lambda sensor is possibly what he was
referring to.

Anyway, nowhere have I found a mention of a high-frequency buzzing being a
normal thing, which is what I was originally trying to figure out. And I
don't know if the frequency valve even exists yet!

Oh well, great way to learn about the fuel injection system though... :)

-Oliver

Oliver Seiler -- Software Developer, Pivotal Software, http://www.pivotal.com
    Scirocco MkII Diary - http://erisian.com/~oseiler/scirocco/index.html




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