"Peter Dohm" wrote in message
...
... BTW, it is probably usefull to think of the Open Loop Mode of the
automotive
ECM at Wide Open Throttle as being analogous to the enrichment valve
feature
of an aircraft carburetor. As soom as you no longer tramp the accelerator
firmly to the floor, the ECM will return to best economy (or possibly
least
emissions) mixture--at least that is the impression which I received from
the limited litterature I read.


Least emissions - it's all about the care and feeding of the three way
catalyst (Oxidizes CO and unburned HC, Reduces NOx (NO and NO2)). At best
economy (lean), the catalyst can't reduce the NOx.

With a wide band (or "universal") oxygen sensor, you can stay closed loop
even during power (or catalyst temperature protection) enrichment - but
those sensor cost $15-$20 more (at OEM prices) so they are less common.

--
Geoff
The Sea Hawk at Wow Way d0t Com
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