Originally Posted by Jhowemca
It seems the whole EGR system is a mistake to me. Sending soot filled exhaust back into an engine to burn is wrong and it will cause problems.
Just to enlighten most folks....
EGR has been with us since the early 1970's gasoline engines.
By recirculating a portion of the exhaust gasses, the flame front is slowed down and combustion temperatures are reduced. High temperature burning of hydrocarbons in a nitrogen/oxygen atmosphere (we are on Earth, aren't we?) produces 'oxides of nitrogen' (NOX) which are highly reactive once they are released back into the atmosphere.
So the EGR system was developed as a way to reduce NOX emissions. It has proven very effective in gasoline engines.
However, since Diesels don't have a throttle plate, getting the semi-pressurized exhaust gasses into the intake manifold that has been pressurized by the turbocharger...can be problematic. Ask VW about their FAIL at it!