O2 Sensor Bias

Kurek, Larry LKurek at ocfexch2.ocf.anl.gov
Mon Aug 24 22:07:48 GMT 1998


Guys:

I've been doing some thinking/analysis (scary) on the recent posts I
have had concerning the variability in the different PCM's I have
installed in my 94 Z28 (LT1).

Got a good question for you...

A lot of guys play with fuel pressure to alter their WOT O2 readings. I
understand that GM runs the stock motors a bit rich, and a lot of guys
lean them out to get more power. So, if the purpose of lowering your
fuel pressure (which affects the atomization of the fuel injected), is
the way to get lower O2 readings, doesn't this affect overall
drivability?

Second, in the factory Helms manual, it states that the PCM applies a
reference 450mv to the O2 sensors, and then reads the voltage variance
from this point to determine the fuel ratio. If this is the case,
shouldn't it be possible to just place a resistor inline with the O2
sensor to "trick" the PCM that the O2 sensor is reading a higher voltage
than it really is, and thereby lean the mixture accordingly? Maybe I'm
barking up the wrong tree here...but is this possible? How? Any
problems?

TTYL!

Larry



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