Quote:
Originally Posted by lowglider
NOx gets reduced to N2 naturally, it just needs a little time.
Soot can be reduced without DPF, just needs more boost (more air) or less fuel in the mixture. Since you have an ECM Eco tune, it should smoke less.
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I'm not really an expert on the emissions after they leave the tailpipe, but I assume it doesn't just harmlessly turn into N2 or it wouldn't be regulated. NOx is a big factor in smog generation. Not that there's any smog issues in rural Indiana.
Smoke generally does go down with more air, and an eco-tune will decrease the engine-out soot, but not the tailpipe out soot. More air can lower soot by say 2-3 times but the DPF takes out 10+ times the soot. If it were just a matter of more air, the manufacturers wouldn't have put them on. Look at Euro 5 vs Euro 6 engines. The Euro 5 PM standards were low, but still high enough that some manufacturers could get by without a DPF. Euro 6 PM standards, however, are so low that a DPF is mandatory for all practiacal purposes.