hunting idle on 5ktq

Huw Powell human747 at
Thu Sep 5 15:40:04 EDT 2002

> I have a problem, the idle speed rapidly varies from 1200 - 1400 rpm and
> repeats about 1 time per second on my 1987 5ktq.

> The car drives great once gas is pressed, but when idle switch closes the
> problem persists.  Anyone have ideas about this?  The thing that baffles me
> most is that unhooking the ISV does not settle the idle down, which
> eliminates the control relay and wiring in my thoughts.

If unplugging the ISV changes nothing, then the ISV system is not doing
its job, I think.  Is there a test point on the 5kt to measure the ISV
duty cycle?  Examine the ECU grounds, which should be somewhere on the
intake manifold, as well.

Huw Powell

More information about the quattro mailing list