OPERATION
The mass of the air su pplied to the cylin ders per
st roke is t he decisive factor for determining the opt i-
mum quan tit y of exhaust gas for the oper ating con -
dition. This is calculated from the Ma ss Air Flow
sensor infor mat ion.
Th e E CM eva lu a t es t h is sign a l a s well a s t h a t
from th e Ch arge Air Pressu re sensor, a nd outputs a
PWM signa l in accor da nce with one of th e maps
st ored in it . Th e signal is sent to the exh aust gas
recir cula tion valve. The map is formula ted t o keep
the NOx as low a s possible. The EGR valve is act u-
ated by an electric positionin g mot or an d has a self
clean ing function. Every tim e the ignition switch is
turned off, the valve rotates twice to eliminate any
carbon deposits.
REMOVAL
NOTE: The EGR and EGR Cooler are serviced as an
assembly.
(1) Disconn ect the n egat ive battery cable.
(2) Partailly dr ain the cooling system (Refer to 7 -
COOLING/ENGINE/COOLANT - STANDARD PRO-
CEDURE).
(3) Lift up on t he ch arge air h ose ret aining clip at
the intake man ifold and disconnect hose with seal
(4) Disconn ect the electrical conn ector at the EGR
position er (Fig. 3).
(5) Disconn ect the E GR cooler hose.
(6) Remove th e EGR fastener s and EGR with
cooler assem bly (Fig. 3).
INSTALLATION
(1) Clean all gasket ma ting surfa ces.
(2) Position the EGR position er t o the int ake man-
ifold with a new g a sket , insta ll bolts a nd tighten to
124 lbs.in (14 N·m) (Fig. 3).
(3) Connect t he EGR positioner elect rical connec-
tor (Fig. 3).
(4) In spect th e seal of t he cha rge air inlet t ube,
repla ce as necessa ry (F ig. 3).
(5) Seat t he charge a ir tube wit h gasket into t he
intake man ifold a nd push down on the cha rge air
tube reta ining clip.
(6) Refill t he cooling system (Refer to7-COOL-
ING/ENGINE/COOLANT - STANDARD PROCE-
DURE ).
(7) Connect nega tive bat tery cable.
VALVE C OO LE R
DESCRIPTION
The exhaust gas recircu lation (EGR) cooler is an
integra ted part of the EGR valve. Coolan t flows
around th e exhaust ga sses, cooling th em befor e they
are remixed with the incom ing air and rebu rned in
the com bustion cham ber (Fig. 4).
Fig. 2 EXHAUST GAS RECIRCULATION
1 - EGR VALVE
2 -CHARGE AIR PRESSURE SENSOR
3 - EXHAUST MANIFOLD
4 - EGR DUCT IN CYLINDER HEAD
5 - INTAKE MANIFOLD
Fig. 3 EGR VALVE
1 - EGR VALVE
2 - INTAKE MANIFOLD
3 - EGR COOLER HOSE
4 - HARNESS CONNECTOR
25 - 6 EXHAUST GAS RECIRCULATION VA
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