Re: toasting an O2 sensor, hesitation at boost, and more

["Fred Munro" <munrof@isys.ca>]

Hi Orin;

    I've been kicking around the idea of installing a digital boost gauge in
the "black hole" in my S4 instrument panel where the trip computer display
used to be (before Audi decided we didn't need it in the '93+ S4's). It
sounds like your 2 digit boost gauge might be a possibility. I assume my ECU
is still providing a signal, but haven't tried to confirm yet.
    Are you displaying colourless digits on a black background (like the
trip computer display) or black digits on a colourless background?
    Might be some interest with S4/S6 owners.

Fred Munro
'94 S4  92k km

----- Original Message -----
From: "Orin Eman" <orin@wolfenet.com>
To: "Brett Dikeman" <brett@pdikeman.ne.mediaone.net>
Cc: <Sargent@symposiafoundation.org>; <200q20v@pdikeman.ne.mediaone.net>;
<quattro@audifans.com>
Sent: Tuesday, November 30, 1999 4:16 AM
Subject: Re: toasting an O2 sensor, hesitation at boost, and more


> > It's perfectly -accurate- since it is derived directly from the
> > pressure sensor the ECU uses.  However, the -precision- is very low
> > and there is a slow refres rate, plus it is unknown whether the
> > ECU/board computer rounds or truncates the measured boost value.
>
> The display is slow because the display in the instrument panel is
> slow.  The signal that goes to the instrument panel isn't slowed down.
>
> > >  A real VDO gauge is a good upgrade...HTH
>
> > That's very true, and something I've considered for a long time.
> > Unable to find a good location though.  I thought about the cigarette
> > lighter socket, but couldn't figure out if the gauge would fit.
> > Certainly already has wiring for the lighting in the gauge.
>
> I've been working with Pete Kunzler on an two digit LED boost guage.
>
> If you have seen my duty cycle meter, the boost meter is based on
> the same board.  The display is currently about 3/4" square by
> 1 1/2" deep.  We are working on a case so it can be mounted under the
> top of the instrument panel cowl.  It fits here easily without
> blocking any existing guage.  Currently, it has been tested reading
> bar, like the existing guage.  It is wired into the same signal
> and reacts so much faster that the digits can merge together as
> they rise... I'll be slowing it down to make it more readable.
> Other options are reading absolute pressure in inches Hg
> or boost in PSI/vacuum to be decided.
>
> A PSI/vacuum display would need a '-' added which would make the
> display wider than it is now (and would preclude mounting it
> in a switch blank).
>
> Personally, I'll probably scale one to inches Hg - 0 to 60 gives
> more resolution than 0 to 2.0 - 1/60th of full scale rather
> than 1/20th of full scale.  For cars with no boost signal
> from the ECU (A4 1.8Ts for example), we are looking into
> pressure transducers, but unfortunately, the Motorola sensor
> that makes most sense seems to be unobtanium at the moment.
>
> Scaling can be done for any pressure sensor, assuming the signal
> is 0 to 5V.
>
> I'm working on dimming it for night.
> We have the options of wiring it to the dash dimmer
> (not so good if you turn the lights on during the day), a separate
> dimmer control or using a photocell to control brightness.
>
> There is a picture of one of the duty cycle meter boards/displays on:
>
> http://www.wolfenet.com/~orin/electronics.html
>
> Comments?
>
> Orin.
>