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

[steveb@falcon.kla-tencor.com (Steven Buchholz)]

 # It might work, but then all your sensor returns would be thru
 # the main engine block ground strap which is carrying the
 # alternator output...  
 # 
 # One of the first things that Bellevue Motorsports did to my
 # ex-UrQ was add another ground strap from the intake manifold
 # to the body!
 # 
... excellent post Orin ... as usual! :)

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)