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Old 07-15-2009, 04:37 PM   #14 (permalink)
cfg83
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1999 Saturn SW2 - '99 Saturn SW2 Wagon
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ConnClark -

Quote:
Originally Posted by ConnClark View Post
Higher engine temps will lead to higher NOx emissions. The same thing goes for lean burn. I don't know if higher engine temps will cause lean burn however. The computer may actually enrich the mixture to try and bring temps down.
I thought cooling was being managed by the on/off of the electric fan. Doesn't the 02 sensor rule, aka the magic 14.7 AFR (Air/Fuel Ratio), aka closed-loop operation? I know it's more complicated than that, but I think this captures the majority of driving conditions, especially because of the way we drive as Ecomodders.

I agree with roflwaffle that a WAI is not "lean burn" per se. I liken it to driving in Death Valley. Less oxygen per volume of air, so less fuel per volume of air (right?!?!?!). I would claim we are simulating operation in an "extreme zone" of the ECU/PCM. This would contribute to the different reactions by different cars. Depending on how the ECU/PCM was programmed, the engine would like/dislike the WAI.

Maybe this discussion deserves it's own thread ("Does a WAI/HAI increase emissions?"). Same for a grille block.

CarloSW2
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