X-Flow Questions, now KS questions

[fahrvergnugen at cox.net (David Utley)]

----- Original Message ----- 
From: "C Boyko" <roccit_53@scirocco.cs.uoguelph.ca>
To: "David Utley" <fahrvergnugen@cox.net>
Cc: <scirocco-l@scirocco.org>; <nlowe79@gmail.com>
Sent: Friday, February 03, 2006 7:31 PM
Subject: Was: X-Flow Questions, now KS questions


> Okay, so I too have been playing with KS/s, in my case, I already have a
> knock sensing ignition in my 8V, as the car has high enough compression to
> warrant it (essentially an RD). Anyway, I'd been reading that sometimes
you
> will get a rattle that acts as a rev specific retard, and I have had a
> consistent flat spot at about 4000 rpm on this car for some time,
> regardless of all kinds of stuff being changed.
> Anyway, to see if the KS made a difference, I unhooked it at the plug to
> the sensor, and the car ran much worse, so it must be working, but is this
> what you'd expect to happen? I know it will retard when it senses a knock,
> but how far (degrees) can it adjust timing, anyone know? Inquiring minds
> and all that.
> Cathy
>
I know it can retard up to three degrees at a time, but that is about all I
remember.  Been a while since I have had a high-comp motor.  If you unhooked
it, I am not sure why it would get worse, unless it is a default retard
(sound like me) mechanism, IE the brain knows it is missing information.
Perhaps someone else will speak on how it works exactly, and what to expect.

I would venture to guess though that one possible reason for the lag around
four K is that you have a vibration that the sensor is picking up as knock.
The sensor is a piezo-type, all it listens for is a certain frequency or
range of frequencies.  Once it 'thinks' it hears that, it backs things down.
These engines are particularly good about having vibrations at 3K-4.5K
depending on many factors, too many to mention.

I remember Dan posted up an article on the use of a DIY device you could
make to actually listen to your engine while it ran.  Using this, YOU would
actually be the knock-sensor.  I was, and am very interested in this, and
hope he will post up where to get the thing again.  The last link he offered
up was from a pay-only online magazine IIRC.

HTH a wee bit.

David