Bad oxygen sensor ?

[Len Sabatine]

   Monitor Fuel Pressure , Read Spark Plug Coloration.  MPH Trap speed  is 
indicative
   of HP [ Consistent with prevailing weather / track conditions. 
Dependance on O2 sensor
   readings are  risky and unreliable as a tuning  tool. [ Hear an Echo ? ].
   Inlet - Exhaust tract leaks , FP volume / delivery and restrictive fuel 
filters are major
   concerns. Defective chassis - engine block grounds can be an additional 
headache.
   Len

>So what do you tune by if not the o2 sensor ? SOTP ? 1/4 mile times ? MPH at
>the end of the quarter ?
>
>----- Original Message -----
>From: <timsiford at hushmail.com>
>To: <gmecm at diy-efi.org>
>Sent: Wednesday, November 08, 2000 10:50 AM
>Subject: Re: Bad oxygen sensor ?
>
>
> > First the standard O2 disclaimer....
> >
> > Tuning by O2 voltages can be highly inaccurate.
> >
> > With that said ... I would check two things...
> > 1) Tape a Fuel Pressure guage to your windshield and have a buddy sit in
> > the passenger seat as you do a WOT run.  Have him watch the FP guage
>ESPECIALLY
> > in 3rd gear to see if your FP is decreasing.
> > 2) Check your header collectors.  In some cases high speeds can act to
>force
> > fresh air into the collectors if they are not tight.  The extra O2 will
> > register on the O2 sensor.
> >
> > Tim
> >
> > At Wed, 8 Nov 2000 09:59:08 -0800, "Edmond" <euro at lvcm.com> wrote:
> >
> > >
> > >
> > >I did several 1/4 mile runs after I installed my Edelbrock headers and
> > >=
> > >brand new o2 sensor. First and second gear are nice smooth 900mV range
> > >=
> > >ramps. Once it hits third gear is starts descending rapidly to about
> > >=
> > >400mV and stays down until I let off the throtle. I wish I was at home
> > >=
> > >so I can show you the exact Diacom graph. I tried giving it more fuel
> > >=
> > >(almost 95 in the VE tables) between 90-100 KPA but it still does this.
> > >=
> > >The engine runs fairly well at WOT, but I cant really tune it w/out
> > >=
> > >gettting some accurate info from the sensor. My old 80K mile o2 sensor
> > >=
> > >in the exhaust manifolds didnt do this at all. Could this indicate a
> > >bad =
> > >sensor ? I should mention at idle it goes from 40-50 to 800-900 almost
> > >=
> > >every 1/2 second. It does this at light cruise too. Maybe it's time
> > >for =
> > >a heated sensor ? Still downt explain the WOT weirdness though since
> > >it =
> > >should be nice and hot.
> > >
> > >
> > >
> > >p.s. I know Bruce already answered this on the thirdgen.org message
> > >=
> > >board, but I wanted some more opinions :)
> > >
> > >
>
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