O2 Sensor Open/Close Loop

[RABBITT_Andrew at mv8.orbeng.com.au]

> The target A/F ratio during WOT can varry from engine to engine.  

this is true, but not in the way you suggest below,

>More specifically, it is related to fuel pressure, fuel injector 
>nozzle design, and injector location.  

this is not true. inasmuch as the effects of these variables are quite 
small to the point of being negligible.

>The objective is to deliver the correct amount of fuel in fine 
>particles to the combustion chamber.  So theoredically, if all the 
>fuel was vaporized, you would not need a WOT enrichment.  

this is also not true.  I get the idea you've confused WOT A/F with 
acceleration enrichment.  WOT is usually richer than stoich because 
this produces best power for thermodynamic reasons.  Acceleration 
enrichment (which also happens at part load) is to maintain the 
setpoint A/F by compensating for manifold wetting effects due to 
changing manifold pressures.

>Therefore, on multi port fuel injection systems with higher 
>pressures, the WOT A/F is very close to stoichiometric.  In fact, 
>some newer vehicles (1996) do not go to open loop during WOT! 

given the above, I find this (very) hard to believe, however if you 
can quote sources, I'd be interested.

Andrew Rabbitt
Orbital Engine Company
Perth, Australia.