MITSUBISHI TRITON 1997 Workshop Manual

± Emission Control System <MPI> ENGINE AND
EMISSION CONTROL17-6
EMISSION CONTROL SYSTEM <MPI>17300010184
GENERAL INFORMATION
The emission control system consists of the following subsystems:

Crankcase emission control system

Evaporative emission control system

Exhaust emission control system
ItemsNameSpecification
Crankcase emission
control systemPositive crankcase ventilation (PCV) valveVariable flow type
(Purpose: HC reduction)
Evaporative emission
control systemCanister
Purge control solenoid valveEquipped
ON/OFF type solenoid valve
(Purpose: HC reduction)
Exhaust emission
control systemAir-fuel ratio control device±MPI systemOxygen sensor feedback type
(Purpose: CO, HC, NOx reduction)
Exhaust gas recirculation system

EGR valve

EGR control solenoid valveEquipped
Single type
Duty cycle type solenoid valve
(Purpose: NOx reduction)
Catalytic converterMonolith type
(Purpose: CO, HC, NOx reduction)
EMISSION CONTROL DEVICE REFERENCE TABLE
Related partsCrankcase
emission
control
systemEvaporative
emission
control
systemAir/fuel
ratio
control
systemCatalytic
converterExhaust
gas
recircula-
tion systemReference
page
PCV valvey17-
Purge control solenoid valvey17-
MPI system componentyyGROUP 13A
Catalytic convertery17-
EGR valvey17-
EGR control solenoid valvey17-

S
ER VIC E S PEC IF IC ATIO NS 17300030173
I te m s S
ta ndard v a lu e P
urg e c o ntr o l s o le noid v a lv e c o il r e sis ta nce ( a t 2 0
C ) W E
G R c o ntr o l s o le noid v a lv e c o il r e sis ta nce ( a t 2 0
C ) W N
um ber N
am e U
se M
D998770 O
xyg en s e nso r
w re nch R
em ova l/ In sta lla tio n o f o xyg en s e nso r

P
osit iv e c ra n kcase v en tila tio n v alv e P
osit iv e c ra nkca se
v e ntila tio n v a lv e

P
urg e c o ntr o l s o le n oid v alv e E
VA PO RATIV E E M IS SIO N C O NTR O L S YSTE M 17300510240
G EN ER AL IN FO RM ATIO N
T he e va pora tiv e e m is sio n c o ntr o l s yste m p re ve nts
f u el v a pours g enera te d in th e fu el ta nk fr o m
e sca pin g in to th e a tm osp here .
F uel v a pours fr o m th e fu el ta nk flo w th ro ugh th e
f u el ta nk p re ssu re c o ntr o l v a lv e a nd v a pour
p ip e/h ose to b e s to re d te m pora rily in th e c a nis te r.
W hen d riv in g th e v e hic le , fu el v a pours s to re d in
t h e c a nis te r flo w th ro ugh th e p urg e s o le noid a nd
p urg e p ort a nd g o in to th e in ta ke m anif o ld to b e s
e nt to th e c o m bustio n c h am ber.
W hen th e e ngin e c o ola nt te m pera tu re is lo w o r
w hen th e in ta ke a ir q uantit y is s m all ( w hen th e
e ngin e is a t id le , fo r e xa m ple ), th e e ngin e c o ntr o l
u nit tu rn s th e p urg e s o le noid o ff to s h ut o ff th e
f u el v a pour flo w to th e in ta ke m anif o ld .
T his d oes n ot o nly in su re th e d riv e abilit y w hen th e
e ngin e is c o ld o r r u nnin g u nder lo w lo ad b ut a ls o
s ta biliz e th e e m is sio n le ve l.
S YSTE M D IA G RAM O
N P
arg e c o ntr o l
s o le noid v a lv e
T
hottle b ody
A ir flo w s e nso r
E ngin e c o ola nt
t e m pera tu re s e nso r
I n ta ke a ir
t e m pera tu re s e nso r
B aro m etr ic p re ssu re
s e nso r A
ir c le aner C
anis te r F
ro m
f u el
t a nk C
ontr o l r e la y B
atte ry
E
ngin e-E C U
C O M PO NEN T L O CATIO N

E
ngin e c o ndit io n N
orm al c o ndit io n 5
3 k P a 3
,0 00 r /m in V
acu um is
m ain ta in ed E
ngin e c o ndit io n N
orm al c o ndit io n 5
3 k P a A
t id le V
acu um is
m ain ta in ed 3
,0 00 r /m in V
acu um w ill le ak
f o r a ppro xim ate ly
3 m in ute s a fte r
t h e e ngin e is
s ta rte d. A fte r 3
m in ute s h ave
p asse d, th e
v a cu um w ill b e
m ain ta in ed
m om enta rily , a fte r
w hic h it w ill a gain
l e ak.* N
O TE
* : The v a cu um w ill le ak c o ntin uously if th e a tm osp heric
p re ssu re is a ppro xim ate ly 7 7 k P a o r le ss, o r th e te m pera tu re
o f th e in ta ke a ir is a ppro xim ate ly 5 0
C o r h ig her.
P U RG E P O RT V A CUUM C HEC K 17300150183
1 . Dis co nnect th e v a cu um h ose ( re d s tr ip e) fr o m th e th ro ttle
b ody p urg e v a cu um n ip ple a nd c o nnect a h and v a cu um
p um p to th e n ip ple . P
lu g P
urg e p ort v a cu um n ip ple

N
orm al c o ndit io n A
pplie d V
acu um le aks N
ot a pplie d V
acu um m ain ta in ed B
atte ry
B
A

E
G R c o ntr o l s o le n oid v alv e E
G R v alv e
1
7-1 4 E
XH AUST G AS R EC IR CULA TIO N ( E G R) S YSTE M 17300520182
G EN ER AL IN FO RM ATIO N
T he e xh aust g as r e cir c u la tio n ( E G R) s yste m lo w ers
t h e n it r o gen o xid e ( N O x) e m is sio n le ve l. W hen t h e
a ir /fu el m ix tu re c o m bustio n te m pera tu re is h ig h,
a la rg e q uantit y o f n it r o gen o xid es ( N O x) is
g enera te d in th e c o m bustio n c h am ber. T here fo re ,
t h is s yste m r e cir c u la te s p art o f e m is sio n g as fr o m t
h e e xh aust p ort o f th e c ylin der h ead to th e
c o m bustio n c h am ber th ro ugh th e in ta ke m anif o ld
t o d ecre ase th e a ir /fu el m ix tu re c o m bustio n
t e m pera tu re , r e su lt in g in r e ductio n o f N O x.
T he E G R flo w r a te is c o ntr o lle d b y th e E G R v a lv e
s o a s n ot to d ecre ase th e d riv e abilit y .
O PER ATIO N
T he E G R v a lv e is b ein g c lo se d a nd d oes n ot
r e cir c u la te e xh aust g ase s u nder o ne o f th e fo llo w in g
c o ndit io ns. O th erw is e , th e E G R v a lv e is o pened
a nd r e cir c u la te s e xh aust g ase s.

The e ngin e c o ola nt te m pera tu re is lo w .

The e ngin e is a t id le .

The th ro ttle v a lv e is w id ely o pened.
S YSTE M D IA G RAM
Engin e c o ola nt
t e m pera tu re s e nso r
O
N
O FF E
G R
c o ntr o l
s o le noid
v a lv e
Air flo w s e nso r
C ra nk a ngle s e nso r
C
ontr o l
r e la y
Engin e-E C U
B
atte ry
E
G R v a lv e
E
A
C O M PO NEN T L O CATIO N

N
orm al v a cu um c o ndit io n O
pen q uic kly N
o v a cu um w ill g enera te
( th e s a m e a s b aro m etr ic
p re ssu re .) N
orm al v a cu um c o ndit io n O
pen q uic kly I
t w ill m om enta rily r is e o ve r
1 3 k P a P
assa ge o f a ir 5
.3 k P a o r le ss A
ir is n ot b lo w n o ut 2
6 k P a o r m ore A
ir is b lo w n o ut E
G R
v a lv e G
re en
s tr ip e G
re en s tr ip e P
lu g E
G R
v a lv e