GM '89 Bosch MAF - was RE: MAF & base fuel tables

[Mark Romans]

This is the reason I would like to get a UEGO!  Regular 02 sensors are not
linear in response either to the rich or lean side.  So other than at stoich
the actual afr is a guess.
Actually the best is the Felpro unit.  Closed loop at WOT, tell it the afr
you want and you are there.  I have  a friend who is a dealer and he uses
his Felpro unit to tune DFI!  (As a UEGO).
Mark
-----Original Message-----
From: Mike Pitts <mpitts at emi.net>
To: gmecm at efi332.eng.ohio-state.edu <gmecm at efi332.eng.ohio-state.edu>
Date: Sunday, June 27, 1999 6:57 AM
Subject: Re: GM '89 Bosch MAF - was RE: MAF & base fuel tables


>The big question is, how do you know 850mv is really 13:1?
>
>Standard O2 sensors behave more like a digital switch than
>an analog feedback sensor.  If you ever look at the response
>curve, you will see it's *extremely* steep around approx 14.5:1
>to 14.9:1.  This is the desired behaviour of a standard O2
>since the ECM switches between lean and rich such that it
>averages out to approx 14.7:1.  Outside of that range, there is
>no guarantee any two O2 sensors will return the same voltage
>for a particular A/F ratio.
>
>Basically all you are guaranteed of at 850mv is that the mixture
>is richer than 14.7:1.   Could be 13:1 or 14:1 or 11:1.
>
>A UEGO is much different.  It has an oxygen pump that is driven
>by the ECM.  The reading portion of the sensor is the same as a
>standard O2 sensor in that is switches around 14:7:1.  The big
>difference is that the ECM can add O2 to the reference side of
>the sensor to move the switch point up and down.  The amount
>of current that the ECM has to supply to maintain the switch
>point determines the actual A/F ratio.  At least, that's the way I
>understand it to work.
>
>-Mike
>
>-----Original Message-----
>>I don't understand the UEGO statment though, the standard o2 sensor woke
>>very well for you application, generaly most of these engine reach amax HP
>>arround 13:1 AFR or about 850 mvdc.
>
>