The
EGR valve first appeared in automobiles in 1972 to counter this
phenomenon. EGR valves basically do this by sending some of the exhaust
gas through the intake manifold back into the cylinders. Because
exhaust gas most often doesn’t burn, it stays and takes up space in the
combustion chamber and lowers the temperature there. Older vehicles
used to have mechanical engine EGR valves, but the newly manufactured
ones have electronic
.
