engine MITSUBISHI COLT 2006 Service Owner's Manual

BASE ENGINE
ENGINE MECHANICAL <4A9>11A-10
CRANKSHAFT PULLEY
AK305072AD
Timing markDamper
A cast iron cranksh af t pulley is used.
The pulley has grooves to eng age with a V -rib bed
belt (5
ribs), which drives an alternat or and a water
pump
.
An ignition timing mark (notch) is st amp ed on the
flang
e of the pulley .
The crankshaft pulley is equipped with a to rsio nal
damp
e r to minimize the torsional vibratio n of th e
cranksha
f t as well as sub s t antia lly redu ce no ise and
vib
r ation at the high spee d rang e.
Flyw he el
AK600531
Ring gear
Flywheel
AB
A cast iron ring g ear is a shrink fit in th e iron casting
of
t h e f l yw he el. T h e f l yw he el is in st a l le d by tigh t e n i n g
six bolt
s .

BASE ENGINE
ENGINE MECHANICAL <4A9>11A-11
DRIVE PLATE
AK401856Ring gearDrive plateAB
A cast iron
ring g ear is a shrin k fit in th e ste e l plate o f
the drive p
l ate. The drive p l ate is inst alled b y tighten
-
ing six bolts .

BASE ENGINE
ENGINE MECHANICAL <4A9>11A-12
TIMING CHAIN TRAIN
AK305075
V.V.T. sprocket
AB
V.V.T. sprocket
timing mark
Timing chain mark
link plate (bule)
Camshaft sprocket
Camshaft sprocket
timing mark Timing chain mark
link plate (bule)
Timing chain mark
link plate (bule)
Crankshaft
sprocket
timing mark
Crankshaft sprocket
Timing mark
Timing chain
tensioner
Tensioner lever
Chain guide
Timing mark
The 2 camshaf
t s are driven by the t i ming chain via
the res
pec tive spro cke t s .
The timing cha i n, consist i ng o f 122 links, is an end-
less chain, conn ecting the cran ksh af t spro cke t with
the camshaf
t and V . V . T . spro cke t s .
The timing cha i n is eq uippe d with 3 mark link p l ates
(blue)
to co rrectly time t he 3 sprocket s with each
other
.
ItemNo. of
teeth
Camshaft sprocket36
V.V.T. sprocket36
Crankshaft sprocket18
TIMING CHAIN TENSIONER
AK305388AB
Retainer
Ball
Coil spring 1
Ball sheet
Coil spring 2
Cam
Pin
Plunger
The timing chain is tensione
d by th e timing chain te n-
sioner , which ha s a b u ilt-in plunge r with plunge r
springs.
The plunger in the timing chain tension e r dire ctly
push
e s th e tension lever , and the pre s sure aut omati
-
cally ad just s the timing chain tension.
A cam is provided t o lock th e plu nger in pla c e a f te r
the eng
ine stop s. This help s prevent the timing chain
from wob
b lin g just af ter th e eng ine st a r t s .
With the timing cha i n ten s io ner in st alled, do not
crank the
engin e in the reverse directio n. This will
force
the plunger to overcome the cam, or e v en
cause oth
e r problems.

BASE ENGINE
ENGINE MECHANICAL <4A9>11A-13
VALVE MECHANISM
AK305076AB
Exhaust valveIntake valve
Exhaust camshaft
Intake camshaft
Spark plug guide
Valve tappet
The valve mechanism is based on a 4-va lve DOHC
(Do
uble Over Head Camsha f t ) d e sign having the
camshaf
t on the u pper valve. Each cylin der has 2
int
a ke valves and 2 exh aust valves, arrang ed in a
V
- shape p a ttern.Camsh a f t rot a tion is transmitte d via va lve t a ppet s to
the respective
valves which ope n and close accord
-
ingly.
VALV E
AK305078
d
d
DD
L
Intake
Exhaust
L
AB
The valves ha ve h eat-resist an ce. Th e entire valve
surface is trea
ted with gas nitriding.ItemIntake valveExhaust valve
Head diameter
mm30.525.5
Stem diameter
mm5.05.0
Overall length
mm89.6190.94

BASE ENGINE
ENGINE MECHANICAL <4A9>11A-14
VALVE STEM SEAL
AK305079AB
Valve stem seal
The valve stem seal e m ploys springs to enh ance
sealing p
e rformance , min i mi zing oil p a ssing do wn to
the por
t.
VALV E S P R I N G
AK300721AB
h
The valve spri ng h a s a dual pitch sp ring to prevent
surging in the h
i gh speed range .
ItemSpecification
Free length mm43.1
No. of spring turns8.49
VA L V E T A PPET
AK300722AB
Thickness
Identification mark
Va lve t app et s are avai lable in 31 th ickne sses, at 0. 02
mm
intervals betwee n 2.70 mm and 3 . 30 mm, to
ensu
r e co rrect valve clearan ce.

BASE ENGINE
ENGINE MECHANICAL <4A9>11A-15
MIVEC (MITSUBISHI INNOVATIVE VALVE TIMING ELECTRONIC CONTROL SYSTEM)
AK300856AD
A
A
A-A
Oil feeder control valve
Oil feeder
control
valve filter
Oil feeder
control
valve filter
bolt
Cylinder head
Cylinder block
V.V.T.sprocket
M I VEC (Mit su bis h i Inn o va tive V a lve tim i ng Elect r o n ic
Con
t rol system) consist s of th e compon ent s illus
-
trated above .
The int a ke valve timing is optimally controlled (con-
tinuously variable) un der the chan ging driving condi-
tions to improv e po we r in th e entire sp eed ra nge.
V. V . T . SPROCKET (V ARIABLE V A L V E TIMING SPROCKET)
AK300857
Vane bushing
AB
SprocketVane roter
V.V.T.sprocket
bolt
Timing mark
Vane housing
Advance oil chamber
Retard oil chamber
Stopper pin
Oil from the oil fe
eder control valve is sent t o the
V
. V . T . sp rocket, moving the vane roto r and thus reg u
-
lating the valve timing.

BASE ENGINE
ENGINE MECHANICAL <4A9>11A-16
CAMSHAFT
AK304999
Intake camshaft
Exhaust camshaft
AB
Hollow section
Advance
oil channel
Retard
oil channel
Cam positon sensing ring
Dowel pinSealing cap
The lightweight camshaf t is ach i eved by the h o llo w
design.
Oil channels run through the int a ke camshaf t,
through
wh ich oil is sent from t he oil fee der co ntrol
valve to
the V . V . T . sprocket.
A cam position sen s in g ring is press-fitt ed onto the
rear port
i on o f the int a ke camshaf t.
ItemDimension
Overall length
mmIntake407.5
Exhaust361.9
Journal mm26
Valve lift mmIntake8.4
Exhaust7.9
OIL FEEDER CONT ROL V A L V E(OCV)
AK302997AB
Spring guideValve sleeve
Plunger spring Spool
O-ring
Insulation coilar
StatorGuide cap Bracket
Yo k eSeal cap
Plunger
Shaft Terminal
Bobbin
Tape
Enameled copper wire
Drain
Drain
Pump
Pressure
chamber
Default
pressure
chamber
The oil fee
der co ntrol valve is essen t ially a solenoid
valve, re
gulat ed by the en gine -ECU or
engin
e -A-M/T -ECU signals to feed o il to the V . V . T .
sprocket
assemb ly t o move the van e rotor .

BASE ENGINE
ENGINE MECHANICAL <4A9>11A-17
TIMING CHAIN CASE
AK305243
Engine support bracket
AB
The engine supp ort bracket, the oil pu mp a nd the
relie
f valve are in tegrate d as we ll as water chamber
of the wat
e r pump.

GENERAL INFORMATION
ENGINE MECHANICAL <4A9>11A-18
GENERAL INFORMATION
M2112000101009
The newly developed 1.5L 4A91 engine features
4-cylinder, 16-valve, and double overhead camshafts
(DOHC).
The engine has the following features.
•Aluminum cylinder block
•MIVEC (Mitsubishi Innovative Valve timing Elec-
tronic Control system)
•Selective valve tappet of direct acting valve sys-
tem for valve clearance adjustment
•Timing chain
MAJOR SPECIFICATIONS
Item4A91
Total displacement mL1,499
Bore × Stro ke mm75 × 84.8
Compression ratio10.0
Compression chamberPentroof-type
Va l v e t i m i n gIntake openingBTDC 31° − AT D C 1 9°
Intake closingABDC 21° − ABDC 71°
Exhaust openingBBDC 39°
Exhaust closingATDC 5°
Maximum output kW (PS)/rpm77 (104)/6,000
Maximum torque N⋅m (kg⋅m)/rpm141 (14.4)/4,000
Fuel systemElectronically controlled multipoint fuel injection
Ignition systemElectronic-controlled 4-coil

BASE ENGINE
ENGINE MECHANICAL <4A9>11A-19
BASE ENGINE
M2112001000875
CYLINDER HEAD
AK305050AB
Spark plug guide
Intake
side
Exhaust
side
Valve guide
The cylinder head is made of aluminu m alloy , which
is light
we ight a nd ha s an excelle nt co oling ef ficiency .
The pentroof type comb ustion chamb e r has a sp a r k
plug in the
cent er . The valve an gle is relatively small,
contributing to size redu
ctio n.
The int a ke an d exhaust port s a r e arrang ed in a
cross-flow construction.
Ea ch cylinde r has a p a ir of
int
a ke port s on one side and a p a ir of e x hau st po rt s
on the
other side .
Each o f the int a ke a nd exhaust ca msh a f t s is sup-
ported by 5 bearin gs. On ea ch camshaf t, th e thrust
load
is suppo rted by No. 1 b earin g. The No . 1 bea r
-
ings for the int a ke and exha ust camshaf t s ha ve a
common bearing
ca p.
VALV E S E AT
AK305052
d
AB
d
DD h
h
Intake
Exhaust
Sintered
alloy valve seat
ItemIntakeExhaust
D (Outer
diameter) mm31.528
d (Inner
diameter) mm2622
h (height) mm6.67.3