Bad oxygen sensor ?

[timsiford at hushmail.com]

Blade,

Read the archives and it will make sense that the stock EGO sensor (narrow 
band) is basically just a switch that will allow you to determine if the 
car is rich or lean.  What to tune by?  Most will say that you need to tune 
by the spark plugs and doing plug cuts.  Another way to tune is through 
the use of a wide band O2 sensor (which costs a lot of $$$$).  You can also 
tune by 1/4 times and the dyno.  I believe that Bruce Plecan also published 
a nice little timing device (660') in the archives.

Tim

At Wed, 8 Nov 2000 11:17:47 -0800, "Edmond" <euro at lvcm.com> wrote:

>
>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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