O2 Sensor Open/Close Loop

[Mark Mason]

RABBITT_Andrew at mv8.orbeng.com.au wrote:

> The reason that closed-loop A/F ratio control was introduced was
> almost entirely emissions control related.  Three-way catalytic
> conversion only operates in an extremely narrow A/F window.  This is
> because you are oxidising HC and CO (so you need excess O2 or another
> oxidising agent) and reducing NOx (so you need a reducing agent)
> simultaneously.
  
> When you go to WOT, no one seems to care how much junk comes out of
> the exhaust, therefore emissions control is thrown out the window and
> the calibration goes rich for best power.  You never see WOT in a
> emissions drive cycle (to date), therefore it doesn't impact on the
> emissions certification.
> 

Would it not be advantageous for the ECM to be in closed loop mode if
the O2 voltage vs. A/F was linear and the ECM regulated the A/F ratio at
WOT to 13:1 ish? 

How do the OEM or aftermarket ECMs calculate/measurem what the WOT
injector pulse width should be for peak power?


Thanks for your help Andrew!


Mark Mason