Re: UrQ FTCU ground on the intake - What the #@$%. -Reply

[Andrew Finney <afinney@tamsconsultants.com>]

My 1982 Coupe and my 1983 UrQ both had/have this right-side
ground strap. Good point Orin about the low voltage signals,
that's the reason, in a nutshell. Maybe it's time to replace all
the braided ground straps as good measure.

Steve, the LED idea is great, what a resource that would be for
me. I never know which of the handful of grounds and sensors
cause my shutoffs. This time I knew it wasn't the fuel pump as
the first few times it happened the car would only hiccup and
the fuel pump would keep sending fuel. The FTCU has one
second to shut the fuel pump off and in my case it didn't have
enough time so I got a small backfire as fuel was sprayed with
no spark for a split second.

Andrew Finney
1983 UrQ.

>>> Steven Buchholz <steveb@falcon.kla-tencor.com>
01/08/98 03:55pm >>>

I noticed that the '85 urQ has such a wire installed as well, as 
did the newer GT Coupe.  The ground wire is a moderate sized
braid 
that went from the right front of the valve cover to a spot on the 
body right above the right headlamp.  I've been meaning to do
this 
to my car as well.

FYI, I found a problem on my '83 urQ where the main ground
braid 
from the engine block to the body (on the left motor mount)
had 
nearly broken from motion/vibration over the years.  If that con-
nection were compromised it might cause additional noise to
be 
coupled into the sensor signals.  

Grounding is a big issue in automobiles today.  I missed an
IEEE 
talk recently about this exact subject.  On my urq the F/TCU
is 
not grounded to the frame of the car through its mounting as it 
is mounted to the glovebox frame.  This is what I would
consider 
to be the appropriate technique to minimize ground loops.  My 
recollection for the 5kCSQ is that there is a ground connection

of the frame of the ECU to the body.  

I've picked up a copy of RDH's code disassembly so I could
evalu-
ate the possibility of adding a PROM address comparator that
would 
latch on an LED if certain addresses were accessed.  I need to

find out if there are unique addresses for the different shut
down 
detection mechanisms.  If this would work you could have a
light 
that comes on when an overboost occurred or one of the other
situa-
tions that causes the ECU to shut off the fuel pump.  

Steve Buchholz
San Jose, CA (USA)