VALVE
DESCRIPTION
Exhaust gas recirculation reduces the quantity of
fresh air supplied to the cylinders per stroke without
having to throttle the air supply. Exhaust gas is
recirculated during all engine speed and engine load
conditions. As a result, emissions are reduced. If a
quantity of exhaust gas is mixed with the air that is
to be used to burn the fuel in the cylinders, the oxy-
gen content is reduced because the exhaust gas is
low in oxygen. The result is that the combustion rate
is reduced, as is the combustion temperature. This
reduces the quantity of NOx that are emitted in the
exhaust gas. (Fig. 2).
The ECM power supply relay has a power off delay
feature. The relay is powered off approximately 15
seconds after the ignition switch is turned off. This
allows for the self-cleaning function of the EGR valve
and a function 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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