NOT A TA said:
Here in FL there's no emissions testing. I do occasionally see someone rolling coal. Seems to me it's primarily unburnt fuel which evaporates. I see a lot of older diesel trucks that leak fuel but there's no laws against that. Leaks out on the pavement and evaporates just like the "coal". Since diesel isn't explosive like gas many owners let them leak for long periods because it's cheaper than fixing them. You can spot the leaker's where they park regularly because the pavement, concrete, or dirt is soaked with a big patch of diesel. Does the EPA, CARB, or any other gov agency worry about leaking diesel contaminating the ground water supply or evaporating? Just seems to me like spending time/money to stop the coal rolling is just more government spending that will have little benefit per dollar spent and the trend is likely to go away anyway.
People seem to be focusing on coal rolling, but there are tons of people with deleted diesel trucks or tuned gas vehicles that aren't obviously rolling coal, and they're arguably doing more harm to people and the environment. Not all tailpipe emissions are equal in their visibility, their impact on people, or their impact on the environment.
Tailpipe emissions are the result of decisions/compromises in the combustion process. And reducing one bad chemical compound often results in increasing another. Direct injection makes this easier to get right, and also easier to screw up as you can inject fuel multiple times in each stroke, and the timing/amount of these fuel injections controls what you get out of the combustion process. If you want to prioritize fuel efficiency, and run lean, you get high temps and lots of invisible NOx. If you want to prioritize making more HP, or rolling coal, you add more fuel which reduces combustion temps and NOx, but increases hydrocarbon and particulate production.
Each of those compounds does different things once it's out in the world. NOx and particulates are both pretty harmful for humans, so the regulators have chosen to reduce those things first with the trade off being that they increased some less harmful emissions like HC and CO2. Essentially they prioritized human health over the environment in the beginning. Now that the stuff that harms people is mostly controlled, those environmentally harmful compounds are also being targeted for reduction.
Modern diesels have gotten so good at cleaning up the stuff after combustion, that they actually run dirtier combustion than older diesels like your Powerstroke. If you measure immediately after the turbo, they make far more NOx than a pre-emissions diesel and then they rely on emissions hardware to clean it up. That's how you get 1000ft-lbs with a warranty and cleaner tailpipe emissions and basically the same fuel economy as 20 years ago. But, if you delete that emissions hardware that's doing all of that cleanup, you've just got that dirtier combustion process creating more tailpipe emissions. And that's before you start trying to make more power, or roll coal, or increase fuel economy. And as Kieth has said, it could mean increasing emissions several orders of magnitude higher than allowed by law.
So the point is that coal rollers are highly visible for enthusiasts and non enthusiasts alike. But for every brodozer rolling coal and making it obvious that they're breaking the law, you've got several others creating just as much harm without making it obvious. Thats why regulators are going after those who enable and profit from emissions modification. It eliminates all of the offenders at the source.
