Duty Cycle w/ VC97 meter

[Huw Powell]

> I recently bought a VC97 multimeter (with duty cycle)  and I was
> trying to check the duty cycle for the ISV.  However i get erroneous
> reading when i attempt to check it.  I am using the connector that is
> hanging loose but when i touch it with only one probe I get a 100%
> duty cycle without even using the other probe.  Something seems
> strange.

Yup, as mentioned, you are giving the meter a puzzle to solve instead of
data it can resolve.  Hook up the other probe to the other connection at
the test point.

No signal could be easily interpreted as a 100% (or 0%) duty cycle.

On the 85-87 CIS-E, that test point, which is in parallel with the ISV,
should start cold fairly high, around 70% I think, and drop to
approximately the minimum it can run at, about 27-30% when warm.

Of course there isn't anything you can adjust to change this, as I
recall, if it really off it is more an indicator of something else being
wrong (air leaks, cruddy throttle body guts, static fuel mixture setting
wrong, bad OXS, etc., etc...).  That's because the "idle adjustment
screw" is supposed to be sealed down tight - it's vestigial from the
earlier cars...

--
Huw Powell

http://www.humanspeakers.com/audi

http://www.humanthoughts.org/