O2 Sensor Open/Close Loop

[RABBITT_Andrew at mv8.orbeng.com.au]

>The vehicle tested is a 1997 GMC 2500 P/U with a 5700 Vortec V-8.  I 
>logged MAP, RPM, TPS (0= closed, 400= WOT), and O2 volts.  You can 
>see the sensor voltage toggles all the way through WOT points.


Interesting data there.  A couple of questions though; you say 400 = 
WOT, but the maximum value is only 396.  Is 400 the exact WOT 
breakpoint (in which case it never went into WOT mode) or is it 
something else?  If so, do you know what it is?  

I noticed a lonely WOT flag at t=9.34 s, but not during the second 
tip-in.  Is this your notation or from the ECU?

I know that the EEC-4 delays open-loop operation for a few seconds 
after entering WOT mode.  Might this be the case for GM, only longer?

Andrew Rabbitt