O2 sensor display.

[David A. Cooley]

At 09:34 PM 4/18/99 -0700, you wrote:
>You guys are over thinking this, 
>
>1) beter precission is only good if you can use it.
>2) The run of the mill sensors are all the same, and are accurate to a 1/10
>AFR value.

Since when?  I've got 2 AC sensors and  a Bosch sensor here that are all 3
for the same app... Each one is so different from the rest it isn't funny.
The bosch sensor runs my BLM down to 80 at idle in Park/Neutral, one of the
AC's sits at 118 at idle, the other is about 127 at idle.
That's more than 1/10 AFR between them.  They also vary a lot depending on
Exhaust temp.

>3) Since this site is about GM ECM's, this feature is built into each and
>every GM ECM/PCM and works very well.

Actually, the O2 as used in GM PCM's doesn't read A/F ratio... ie: if it
commands 14.7:1 you don't see a steady 500mv out of the O2.  The PCM
bounces fuel from rich to lean rapidly and looks for the O2 sensor to
"cross over", switch from rich voltage to lean voltage.  It tries to
balance the fuel so the time in rich and lean balances out.  A richer A/F
makes it stay longer in the rich, a leaner makes it stay longer in the lean.

>
>I wouild suggest a focus on how to get the benifits of the existing o2
>sensor. All GM systems will tell you exactly what it wants fir fuel
>predictions.

Sorry, but it is programmed with a value as a pseudo reference only.
===========================================================
           David Cooley N5XMT           Internet: N5XMT at bellsouth.net
     Packet: N5XMT at KQ4LO.#INT.NC.USA.NA   T.A.P.R. Member #7068
   Sponges grow in the ocean... Wonder how deep it would be if they didn't?!
===========================================================