Dyno with O2 Sensor

[Berkeley and Bill Conner]

My last dyno runs showed showed that I have lost about 5-7 WHP
throughout the power range without making any intentional changes to my
setup (see mods in signature line below).  The A/F ratio indicates that
the engine is running leaner now than when it was putting out more
power.  Whereas previously the A/F ratio had been 12.9-13.1, the last
runs showed ratios in the mid 13s, peaking as high as 13.9.  The A/F
ratios were measured using a wide band O2 sensor in the tail pipe,  so
the first thing I'm going to do is go back and get more data with the
sensor screwed into the O2 bung on my header.  Will the car run OK on
the dyno without the O2 sensor feeding data to the ECU?    Does it
matter whether I unplug the removed O2 sensor or leave it plugged into
the wiring harness?  Is there anything I should be aware of, or watchful
for as I make these runs?

I will also be installing a fuel pressure gauge this weekend to see how
the fuel pump and FPR are working.  Any advice is appreciated.

Bill Conner
(1993 Classic with PR CAI, S3s, JWT S3 ECU, HS header, HKS exhaust)