The big Diesel emission scandal in the world of cars

The important things to know if you’re curious about the Diesel scandal of the decade.

First thing first, what is Diesel and how does it work?

Diesel engine was discovered by? Rudolph Diesel  hence the name of the engine type. Diesel engine works like compressing the air to a very small space by the piston which super heats the air and injecting the fuel at a very fine mist at the right moment which creates a bang (explosion) and drives the piston downwards.Because of the way it works, it is on average 30 percent more efficient than a gasoline piston engine, which means it produces way less CO2, on the other hand it produces way more NOX (nitrogen oxides) than a gasoline engine.

The Diesel engine is a work horse, due to its efficiency and high torque and robust design, it’s the favorite of frugal drivers and 18 wheelers, trains and ocean liners.

Most people don’t realize the air which is used to create combustion in a piston engine is 78 percent nitrogen 20.8 percent oxygen the remaining gases are irrelevant in the combustion process. Nitrogen is a inert gas which only converts to nitrous oxides if put under high heat and pressure.

The question is; What went wrong with the NOX treatment on the Diesel engines which threw the entire car industry into a nosedive around the world?

Today on modern Diesel engines we have selective catalyst systems which reduces the  allowable limit of NOX to 0.07 gram/kilometers on average, and from 2017 it ned to be maximum  0.03 gram /kilometer.

There are cars with SCR reduction urea injection, from 09 on certain most makes and models (except very small diesels, due to their small displacement), they were not required to have the SCR system. It is mandatory from 2015 onward.

The problem was with the tested cars, the manufacturer had manipulated the engine software to have a dual operating system and those cars had no SCR system yet.

Keep in mind the regulations in North America way more stringent than Europe where NOX reduction and treatment way more lenient towards the Diesel engines. All modern diesels have from 2015 on an SCR system which uses a particulate filter to a ammonia based (urea) liquid injection into the exhaust stream to reduce NOX to a very low level at the tailpipe emission.

This is quiet an elaborate system with various sensors to detect unburned oxygen to NOX sensor and temperature and pressure sensors to all work together, to cut and reduce tail pipe emissions to a very very low level.

The scandal broke out when a small independent firm tried to prove the fact that small diesel engines are clean from a well known German car manufacturer.  Their diesel cars being sold in America had a program in its computer, that could detect when they were being tested, changing the performance accordingly to improve results.

During normal driving condition, the vehicles  dual operating system enhanced the engine performance, which raised the emissions to a high level of NOX content.  NOX reacting with sunlight could create an irritant, especially critical in a hot climate like California for instance.

Most manufacturers Diesel equipped cars meets or exceeds the government mandated stringent emission standards. In this case the whole dual system was a deliberate act on behalf of the largest German car manufacturer whom build their reputation on the fiction of having build clean Diesels.

Their deception hurt the entire car industry which will have to prove it to the world they can be trusted when it comes to building efficient clean Diesel powered automobiles.

There are some lessons to be learned from this fiasco. Draw your own conclusions and enjoy the ride.


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