O2 sensor bias

[John Wickerham]

Walter,

What you describe sounds reasonable.  All I know is that I had hoped
to reduce slightly the amount of fuel injected and thereby get a bit
better mileage.  It did reduce fuel (I think), but any gains I might
have gotten were offset by additional EGR.

I would be willing to post the schematic of this device if it was
mine - but it's not.  This fellow sells them and the plans to them.
There's enough smart people on this list however to figure it out,
so perhaps an impassioned plea to all the gifted electrical guys
out there would produce a schematic.  THis is simple compared to
the stuff that has been put forth for injector drivers and such.

If you are interested in persuing the schematics for this device
(it's called an EFIE by George), you can order them from him for
a few dollars.  Look under "fuel savers" at www.eagle-research.com.
Find the EFIE and there should be a description.  There is a
printable order form that you can then send in.  He sells both
the device and the schematic.

Thanks,
John

>I suspect that the egr is increased when the computer spends more time
>leaning than it does richening. In other words, it's not increasing
>egr in response to a shorter pulse, but to increased duration of
>the richening cycle versus the leaning cycle. 
>These are the reasons (those with knowledge of GM ecm insides correct me)
>To know that the injector duration is smaller than it should be the
>ecm would need to be constantly comparing actual pulse duration with
>a reference fuel map. As I understand it though, the inj duration is
>already generated from the reference fuel map.
>>From my experience with L-jet cars, 0-30 accelerations seem to be made
>lean on purpose, probably for better city mileage numbers. If this
>is the same for GM cars, the extra time the O2 spends lean during
>acceleration is probably used as a trigger for increased egr. I can
>see this being extended to all driving conditions: any time the 02
>spends more time lean than rich, the egr is activated until the
>lean and rich times are equal. If the added 02 circuit unbalances
>these times, for all conditions and at all times, then the ecm would
>just keep increasing the egr until it's maxed out.
>It would be nice to be able to take a look at this 02 circuit add-on
>and get an idea of exactly what it's doing, but I couldn't find it
>on the web site you mentioned. Seems like what is needed (at least
>to see if it fixes the egr problem) is a circuit that changes the
>o2 voltage but somehow makes the ecm cycle evenly.
>As someone used to be fond of saying, maybe the above is just a
>brain f@#t! Any comments? Walter