The EGR valve for "Exhaust Gas Recirculation" be re-circulation of exhaust gas has been placed on the exhaust line to combat poor performance in terms of pollution. The major manufacturers have adopted since 1993 on petrol and diesel engines to meet European emission standards. This perfectly anti-mechanical principle is to recirculate in a diesel engine of the gases loaded with soot and NOx.
This surprising yourself from engineers engine has the advantage of very cheap cost to the design.
This is more true when one becomes user, when the EGR valve is completely fouled it more correctly its use. Soot cooling foul the intake system, and especially the valve that then prevents normal breathing of the engine. He naturally loses its power and thus its good performance. The engine clogs up breaking down.
On current vehicles to central electronic control, when the lights come on, the damage is done and the evil malfunctions are very difficult to diagnose.
How does it work?
The diesel engine works in excess air, so much in the presence of oxygen, which automatically results in high nitrogen oxide (NOx) emissions, the pollutant from diesel by its particles. By the EGR valve entering the intake of exhaust gas poor in oxygen, reducing the amount available in the cylinder and reducing the amount of NOx. As it should run as intermediate systems and cycles, it is controlled by a computer. It hangs generally open, and the excess of recirculated exhaust gas leads to poor combustion in the cylinders (stuffiness) increase soot, carbon monoxide and hydrocarbons and possible degradation of the pot of oxidation.
2002 before the valve controls were tires since they are electric.
The first did not send any information to the dashboard, the second alert management in general lighting a lamp on the dashboard. Unfortunately it is only when the flow meter, which measures the amount and quality of the air passage detects the anomaly that the witness table lights and copying the information management often the engine is then in degraded mode. Since the user does not know the procedure, he panics because he was still in the process of doubling a truck! ! !
Many technical solutions exist to clean the circuits and restore the vehicle to its previous state, this will not be our problem when considering that the goal will be to devise amicable or contentious way the manufacturer that the vehicle has a hidden defect, which may be appointed by a court "hidden defect within the meaning of Article 1641 and following of the civil code"
Jean Claude M.
The big problems of the EGR valve is that it is necessary to reduce NOx. It is the only current way to reduce these emissions on diesel engine (except for a NOx trap or SCR).
On the other hand, the more EGR you put, the more particles you make (this is the famous "NOx / Particles compromise" which makes all engine manufacturers have nightmares) ...
And here is an article on the EGR valve "scandal", published in Auto-Moto in September 2005:
Article to download in .pdf here: https://www.econologie.com/telechargeme ... r-article/