[froggit]

> belch out thick black lib-ownin' ball-crushin' smoke, damaging their own engine in the process.

The black smoke belching is caused by a fuel rich air mixture that leads to incomplete combustion and is pumped out of the engine as a burning cloud of smog. While this can cause problems with carbon build-up in the combustion chambers, it's not especially difficult to clean that out before the engine suffers permanent damage. Most often the worst case is fouled spark plugs, which are wear items meant to be replaced at regular intervals.

The real damage occurs in the exhaust plumbing, typically rendering the oxygen sensors inoperative and cooking the catalytic converter. However, a common way to induce black smoke is by hardwiring the oxygen sensors to report the engine needs more fuel, so it's not like the oxygen sensors were typically working anyway.

Likewise, in many parts of the country where this sort of "coal rolling" is common, it's also common for the catalytic converter to be forcibly removed from the vehicle and pawned off for the platinum mesh inside by a couple meth heads looking for their next fix, which has the side effect of preventing it from being damaged. The missing portion of the exhaust pipe is frequently repaired by welding in a straight pipe, allowing the black smoke to flow more freely while also making the exhaust notably louder and adding the scent of immediate global warming (note: this is pretty much super illegal in most states).

[officeplant]

>Most often the worst case is fouled spark plugs, which are wear items meant to be replaced at regular intervals.

You do realize we are talking about diesel's here, they don't use spark plugs. They use Glow plugs because diesel engines don't rely on spark to cause combustion, its just heat and pressure.

Nor do they rely on downstream oxygen sensors like a gasoline powered car. They just use tuning software to up the turbo boost pressures and adjust the fuel mapping. Some guys literally just have a button to hit to briefly swap to an alternative fuel map that maxes out those fuel injectors briefly.

The main problem with rolling coal is damage caused by the extra exhaust temperatures from dumping extra fuel into the combustion process. Plus the fouling up of entire exhaust system over time. Sometimes causing fires within the exhaust system (see Ford's 6.0L Power Stroke meltdowns on youtube)