[V8] O2 ground

[Tony and Lillie]

So, here's the question. Why not ground to the body? Are the body and engine 
not the same in reference to ground. All power sources lead to ground 
eventually. We ran into this quite often on aircraft components. The only 
difference is when you are running a signal of a higher frequency. Then, you 
usually use a resistor or capacitor to keep the signal from affecting the 
power source (usually of a lower frequency). When you have a high frequency 
riding over a lower frequency, it can cause surges that are heard through 
audio components.

However, none of this is the case here. There is no resistor or cap between 
the body and engine. So, if you have a good connection between the body and 
engine, you can use either. If you don't, or suspect the connection or 
cabling is bad, replace it. If not, you are asking for trouble. Just ask 
anyone with and older VW.

Tony Hoffman

----- Original Message ----- 
From: "Buchholz, Steven" <Steven.Buchholz at kla-tencor.com>
To: <v8 at audifans.com>
Sent: Wednesday, October 12, 2005 6:29 PM
Subject: Re: [V8] O2 ground


> If you bolt it to anything that has a good electrical connection to the
> engine block you are probably OK.  As I noted earlier, Audi did have a
> ground specifically intended for the sensor inputs to the ECU ... the
> *best* place to ground the OXS is to this exact point on the back of the
> engine.
>
> If you attempt to ground the OXS to anything else you are asking for
> trouble ... especially if you have any thoughts of grounding the OXS to
> the body of the car.  If that's the only place you can find, I would
> strongly recommend that you forget about trying to make a 4-wire work
> and go back to a 3-wire and depend on the connection between the engine
> block and the exhaust header.
>