[V8] Oxygen sensor.

dsaad at icehouse.net dsaad at icehouse.net
Fri Jan 30 13:24:19 EST 2004

To solve for/prevent that problem I used the ground side of the heater wires. 
(one of the heater wires) Seems to work fine.


Quoting "Buchholz, Steven" <Steven.Buchholz at kla-tencor.com>:

> ... you should be very careful when trying to consider where to connect
> your
> extra ground lead on the 4-wire OXS.  It is very easy to create a ground
> loop and end up making things worse than with the factory 3-wire.  When
> I
> did the engine swap on #2 I learned that all of the engine wiring goes
> directly through a wiring harness that sits below the throttle linkage
> at
> the back of the engine ... this includes ground wires that go to the
> ECU.
> Let's say you had a situation where the exhaust crossover pipe wasn't
> well
> connected to the engine ground ... now the OXS signal can get altered by
> the
> difference in ground voltage between where you have the OXS grounded and
> the
> actual engine block.  Remember that tenths of a volt can make a
> difference
> in this sort of signal, and when you consider the high ground currents
> between the engine block and the body of the car it isn't that hard to
> imagine tenths of a volt changes in the ground reference.  Grounding in
> a
> modern car is not as simple as in the old days when all you needed was
> power
> for the starter and lights!
> I fully agree that you may well realize an improvement in the OXS'
> signal to
> the ECU by switching to a 4-wire OXS, but you should think carefully
> about
> the grounding.  My recommendation would be to find the ground lugs below
> the
> left distributor and attach the fourth wire to one of the two ground
> points
> there on the back of the engine block.  
> Final comment ... I got a non-Bosch 3-wire universal OXS from my BiL's
> a while back and installed it on #344.  Overall I'd say that it works
> OK,
> but there is a point a couple of minutes after a cold start where the
> engine
> runs poorly for 15 seconds or so ... I suspect this to be due to the ECU
> thinking the OXS is warmed up when in fact it has not yet ... I will not
> install another OXS in the car that is not made by Bosch and have the
> same
> general design as the standard part ...
> Steve B.
> San Jose, Kaleefohnia (USA)
> > 
> > I also use a Ford 4-wire and it works fine. I like the extra 
> > ground wire as I 
> > think it helps give a more consistent reading and the 
> > Motronic seems pretty sensitive to this.
> > 
> > If you use a 3-wire it is a good idea to make sure the 
> > exhaust pipe is well grounded.
> > 
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