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Old 06-25-2009, 02:37 PM   #35 (permalink)
rkcarguy
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Join Date: Mar 2009
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I've heard(can anyone verify) that the base problem with much of this technology is that our EPA is corrupt and emissions limits here are based on emissions per X amount of fuel used, not per mile. So a big guzzling SUV getting 10mpg can emit pollutants at the same percentage per unit of fuel consumed, but if the 35mpg car emits 1.01 times the pollutants of the SUV, but overall it's less than a 1/3rd of the total emissions per mile of the SUV, it still fails.
Regarding the lean burn, the OBD-2 system uses the knock sensor to keep lean burn at the edge of detonation, instead of the wideband o2 sensor like the OBD-1 VX. Fuel is pulled back to the brink of detonation, not the timing.
The perimeters of this computers tuning were worked around emissions, not efficiency. I don't doubt that the system exit's lean burn and dumps fuel to heat the cat to keep it operating. I've heard that the new diesels are doing the same thing and have lower mpg ratings as a result.
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