Adding another O2 sensor

[Walter Sherwin]

Almost impossible to accomplish when headers (long or short) come out to
"play".  Easily accounted for via other means (unless getting into some of
the closed loop time lag corrective/additive dependant stuff)..............

Walt.




> Only thing I see as a possible engineering point is that the location of
the
> sensor be as close to the distance from the valve that the OE location in
> the stock manifold was... but you may have already assumed to do this
this.
> Switch 'bounce" a factor anyone?  not for long I guess - not significant.
>
> My O2 cents.
>
>
> ----- Original Message -----
> From: Walter Sherwin <wsherwin at home.com>
> To: <gmecm at diy-efi.org>
> Sent: Wednesday, November 01, 2000 6:21 PM
> Subject: Re: Adding another O2 sensor
>
>
> > Actually,  you have a good idea there!..........By placing one standard
> zirc
> > oxygen sensor at each header collector, and by running the outputs up to
a
> > toggle switch mounted in the cabin, you will have the ability to flip
back
> > and forth to determine whether the fueling is balanced from bank to bank
> > (assuming you are still running bank fire).  You could then use one ALDL
> > scan tool device to observe either O2 output, and make a comparison
either
> > while at idle or while on the road.  Would make things "nice" when
> tracking
> > down a bad cylinder, or injector, or combo.
> >
> > Now let's say you find one day that the fueling is "off" between banks,
> due
> > to say recent porting & runners & etc.,  and that your cylinders and
> > injectors are in fine working order.  Are you then SOL for adjustability
> > without reverting to elaborate sequential EFI control?  Absolutely not!
> > Accel make a plug-in product called the "VIC" (short for Variable
Injector
> > Controller) which can offer +/- 10% BPW adjustment per injector, while
> using
> > your conventional bank fire ECM triggers and wiring.  It's as simple as
> > twisting a knob per injector, and then locking it into position.  Kinda
> like
> > having SEFI, but without all the other associated hassles.  Two O2's,
> > together with some plug reading and a VIC, could get you to where you
need
> > to ultimately be for balanced fueling.
> >
> > However, for the two zirc O2 bank readings to be meaningfully comparable
> to
> > each other, you'll want to make sure that your sensors share the exact
> same
> > ground plane.  With custom exhaust parts inserted in the ground path(s)
> > between your sensor(s) and the ECM O2 LO sense circuitry, it would be
> > prudent to either:  1)run a braided ground strap from one header
collector
> > to the other, OR   2)see a recent post to this list regarding standard
> zirc
> > O2's with redundant external ground leads built-in (GM and AC Delco
P/N's
> > were supplied).
> >
> > Carry this dual O2 concept one step further.............You could even
> > purchase a couple of cheap (but useful) Halmeter AF30 O2 monitors, and
> stick
> > them side by each on the dash.  This would expose a huge wealth of
insight
> > with regards to comparative O2 trends and magnitudes between banks.  If
> you
> > later got "fancy", you could probably datalog the raw zirc O2 signals
and
> > get to the point of examining each individual cylinder event on a trend
> > basis.  Although this approach would not necessarily be super accurate
in
> > terms of absolute A/F ratio,  it would at least be somewhat repeatable
and
> > illustrative for comparo purposes between cylinders.
> >
> >
> > Walt.
> >
> >
> >
> >
> > > Car = 1990 IROC-Z
> > > From the factory these cars have one O2 in the driver's side exhaust
> > manifold.
> > >
> > > Since I will be installing Hooker long tubes I have been contemplating
> the
> > > installation of an O2 sensor in the passenger side header as well as
the
> > > driver's side header.  Then, I was thinking of running a SPDT toggle
> > switch
> > > so that I could switch between the O2s to determine how one side of
the
> > > engine is running as compared to the other side.
> > >
> > > Just figured I would throw this out into the air since the list is
> pretty
> > > dead today.  Besides the obvious con of the extra expense ... can
anyone
> > > think of a reason not to do this (besides the whole geek factor)?
Would
> > > the fact that O2s are not accurate be enough of a reason for not doing
> > this?
> > >  If so, then why is it that later F-bodies run an O2 sensor for each
> side
> > > of the engine (one for each bank of injectors).
> > >
> > > Heh heh - wouldn't it be cool if WB O2s were cheap and we could
install
> > > a WB O2 into EACH primary tube of the header and then tune each
cylinder
> > > for maximum power through sequential fuel injector tuning?  That would
> be
> > > really cool.  Yea - I know I am just wishing ... sometimes its cool to
> > wish.
> > >
> > > Tim
> >
>
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