VALVE
DESCRIPTION
Exhaust ga s recircu lation reduces t he qua ntity of
fresh air su pplied to the cylin ders per stroke withou t
having to throttle th e air supply. Exh aust gas is
recir cula ted during all en gin e speed an d engine load
conditions. As a result, emission s a re reduced. If a
quan tity of exhaust gas is mixed with the a ir th at is
to be u sed to bur n t he fuel in the cylinder s, the oxy-
gen cont ent is redu ced beca use the exh aust gas is
low in oxygen. The r esu lt is that th e combustion ra te
is reduced, as is t he combustion temper ature. Th is
reduces the quan tity of NOx th at are em itted in the
exha ust gas. (Fig. 2).
The ECM power supply relay h as a power off delay
featu re. The relay is powered off approxima tely 15
seconds aft er th e ignition swit ch is turn ed off. This
allows for the self-clea nin g function of the EGR va lve
and a funct ion check of the sensors for diagnosis pur-
poses.
Fig. 1 EGR AND COOLER
1 - EGR VALVE 3 - COOLING FINS
2 - COOLANT PASSAGE 4 - EXHAUST GAS PASSAGE
VA EXHAUST GAS RECIRCULATION 25 - 5
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