O2 Sensor Bias, fuel pressure changes

[ECMnut at aol.com]

Greg,
The problem is; manipulating fuel pressure, to get your WOT O2 readings
up or down, also impacts "closed loop" behavior.   On my GMC turbo 4.3,
my best dragstrip performance occured with 47 PSI of base pressure.  Stock is
10 psi less than that.  The best runs had O2 readings in the mid 900's.  A
long day at the track, with raised fuel pressure, caused the truck to stall as
I would start it to move forward in the lanes.  Pulling the ECM fuse between
runs made it "forget" the compensations it had learned (BLM), which helped
drivability, and reduced stalling..  For good reading on BLM, check out
"tuning secrets" page at 
      http://members.aol.com/efiperform/calibrat.htm
I believe the bulk of it was authored by a Buick engineer. 
HTH,

Mike V.
back to scouring the 101 archives....
my brain isn't very absorbent..

In a message dated 8/27/98 7:51:27 PM Eastern Daylight Time,
summit01 at nationwide.net writes:
> Excuse me, kind of new here. What's wrong with lowering fuel pressure to
lean
>  out the mixture "across the board" as you want. Since GM ECMs go into open
>  loop at wide open throttle (signaled by the throttle position sensor) the 
> best
>  way to lean it out, or richen it for that matter, is by changing the base 
> fuel
>  pressure. Lower the pressure until you get the O2 readings in the range you
>  want (800-850?). Unless your base fuel maps are way off or the injectors
are
>  sized wrong that should work, right?
>  greg kring