[urq] After-market Boost Gauge Install

[Pasqualoni, James E]

Thanks Steve.  I think the oe boost gauge is actually plumbed off the hose
from the IM to the ECU.  I found this out one day when the boost gauge
stopped working during some spirited driving.  All of a sudden, the timing
seemed to be way off-I was getting lots of turbo noise and pinging.  My
thought was that the boost gauge had to have been piggy-backing off the ecu
line, and since the ecu wasn't reading boost, it was completely confused.
Sure enough, when I replaced the IM to ecu line, the boost gauge started
working again.  I haven't disassembled the oe cluster yet, so I was unsure
if the boost gauge was electrical or mechanical.  But now I know!

Thanks again,
Jim

-----Original Message-----
From: urq-bounces+james.pasqualoni=gs.com at audifans.com
[mailto:urq-bounces+james.pasqualoni=gs.com at audifans.com] On Behalf Of
Buchholz, Steven
Sent: Friday, May 27, 2005 5:04 PM
To: urq at audifans.com
Subject: RE: [urq] After-market Boost Gauge Install


>From what I've seen the standard practice in designing a vehicle is to
minimize the failure points for critical systems to increase the overall
reliability in those areas.  An example of this principle is that you will
find that most critical electrical systems are powered directly from the
ignition switch rather than through a load reduction relay. This way the
engine will still run even if the relay fails.  That same principle appears
to have been applied to the manifold pressure connection for the ECU ... the
line is pretty much point to point.  If you tee anything else into the
"circuit" then there are more failures that would affect the ECU's view of
its world.  I'd also be a little concerned in a time delay in the signal the
ECU sees due to the extra volume of the added line and the gauge.  

All in all it is probably a minor nit, so there really isn't any risk to
doing what you propose.  There should already be a vacuum line plumbed for
the dash gauge ... if I were to add a VDO turbo gauge I'd probably use that
source.  

Steve B
San Jose, CA (USA)
> 
> I am installing a VDO boost gauge in my dash extension.  I'd like to
tee it
> off of the hose running to the ecu for diagnostic purposes (easy to
tell
> when hose from IM has a leak or becomes disconnected).  Any BTDT?  Can
I
> connect in aft of the firewall?
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