crank MITSUBISHI ECLIPSE 1990 User Guide

q7 --_-.-ENGINE
- General Information9-3TECHNICAL FEATURES
HIGH PERFORMANCE AND . . .._..............1. The DOHC 16-valve engine ensures excellent intake and exhaust
FUEL ECONOMYefficiency.
2. The rocker arm is of the roller-type-cam-follower design which Iminimizes friction loss.
3. The combustion chamber is of the pentroof type with a squish
area that offers outstanding combustion efficiency.
4. The multipoint fuel injection system is electronically
controlled.5. The intake manifold is the inertia supercharging type which
improves intake efficiency and the dual-type exhaust manifold
offers good exhaust efficiency.
6. The two-coil type electronic control ignition system ensures
good ignition performance.
LOW VIBRATION AND. . . . . . ..I.................1. The hydraulic lash adjuster, together with the roller rocker arm,
LOW NOISEcontributes to reduced operating noise of the valve mechanism.
2. A cogged type belt is used to drive the camshaft.
3. The auto tensioner maintains the optimum timing belt tension.
4. The torsional damper reduces twisting vibration in the crankshaft’
to a minimum.
5. The silent shaft system reduces engine vibration and rolling
’moment to a minimum
SERVICEABILITY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1. The self-diagnosis system makes troubleshooting easier.
2. The lash adjuster eliminates the need for valve clearance
adjustment.3. The auto tensioner eliminates the need for timing belt
tension adjustment.
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9-8ENGINE - Base Engine
0
Ri
Bearing cap No.
No. 6R: Exhaust side
cyL: intake stdeNo. 5\-
CLNo.4 bd
P
j
CamshaftQsproc:kets -
sideintake sideno. 16EN0077ROCKER COVER
Rocker cover
From airintake
hose
erection that the spark
plug cable is installed.
6EN0378Breather plate
Rocker cover
To intakemanifoldPositive crankcase
ventilation valve
Viewed from bottom
of rocker cover
l Blow-by gas
C$ Fresh air6EN0384Installed inside the rocker cover is the breather plate. Theblowby gas passes through the space between the breather
plate and rocker cover and is drawn through the positive-
crankcase-ventilation valve to the intake manifold. As a result,
-fresh air is drawn to the engine cylinders.

ENGINE- Base Engine9-11 7Oil jet
Front mark
6ENOO6lCONNECTING ROD
(1) The same connecting rod is used as that used in the 4663SOHC engine.
(2) The oil jet provided in the shoulder of the connecting rod is
used to lubricate the cylinder wall.
(3) The big-end bearing is the kelmet metal with metal backing.
CRANKSHAFT(1) The crankshaft is supported by the five main bearings.
(2) The oil passages drilled to the crankpins permit the flow of
lubricating oil from the main bearing to the connecting rod
bearing.(3) The crankshaft has been subjected to special surface
treatment. Therefore, do not grind it for reuse.
(4) The main bearing is an aluminum alloy with a backing of
another metal. The center bearing is provided with flanges
to receive the thrust load of the crankshaft.
Oil passage
6EN0089
16ENOOQO
Oil passage
INo. 51MAIN BEARING CAPSThe No. 1 and No. 2 main bearing caps are joined, as are the
No. 4 and No. 5 main bearing caps, by means of a beam to
minimize vibration of the bearing saddles and to enhance
rigidity of the crankshaft support.
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.--. _A

9-12
CRANKSHAFT PULLEY
ENGINE- Base EngineDrives the water
pump and alternator
Hub-
Pulley -Drives the air
conditioner
compressor
Fin
Rubber
6EMI2526EN0145 Timing belt cover
(1) The crankshaft pulley not only drives the water
pump and alternator, but also functions as a
torsional damper to reduce torsional vibration of
the crankshaft.
SILENT SHAFT SYSTEM(2) There are fins provided at the back of the pulley
that ventilate the inside of the timing belt cover:
when the pulley rotates, they draw air out of the._
timing belt cover.
Forward
@
/I
Center of crankshaftSilent shaft --
6ENl32The silent shaft system counteracts the secondaryreducing the vibration and noise generated by the
exciting moment in the engine’s vertical direction asengine. The system is exactly the same as that used
t uluv -well as the rolling moment, thereby drastically
in the conventional 4G63-SOHC engine.
-------_---.--- __.----_. _... ,.

ENGINE- Base Engine9-17CAMSHAR
Exhaust camshaftStamped identification mark
-
-
k--JL---J
No. 1 camsNo. 2 camsNo. 3 cams
No. 4 camsIntake camshaftIt’ II’ II1
NOTEJ = Journal
Crank angle sensor6EN0112
(1) Each camshaft is supported by the six bearings.(2) A hexagon between the No. 1 and No. 2 cams is
provided for holding the camshaft with a wrench
when loosening or tightening the
catishaftsprocket bolt.
TIMING BELT TRAIN
Exhmmt rid.Intake tide
Camshatt sprookec(No. of teeth: 461Camshaft sprocket(No. of teeth: 461
MN0139
6tNOl10
011 Pump stmoket(No. o! teeth: 18)
Crankshatr spmokst(No. of loath: 2416EN0114

9-22ENGINE- Mounts
Principalaxi? of inertia
The
::I: indicates mount positions.01 RO77OlAbsorption action during minute vibrations
ICavity
CavityOlRcl767l
Absorption during large vibrations or “rolling”
Cavity
CavityPRINCIPAL AXIS INERTIA SUPPORT SYSTEM
The vibrations generated from the engine and drive train
consist of such eiements as vertical vibrations caused by the
engine’s combustion processes, as well as
rollings caused by
the torque reaction force of the tyres and the crankshaft
rotation etc.
In order to effectively suppress these vibrations, the principal
axis of inertia support system, by which the components that
contact the principal axis of inertia are mounted, is employed.
INSULATORS
Absorption of Minute Vibrations
The minute vibrations that are generated during idling and
during driving are absorbed because the spring constant is low
as a result of the fact that insulator A only causes vibration of
the space within the cavity.
Absorption of Larger Vibrations
The larger vibrations that are generated during starting from a
_stop and during acceleration are absorbed because insulator A
and insulator
B contact, and the spring constant becomes high.

FUEL SYSTEM - General14-3The fuel is supplied under pressure by the in-tanksent to the engine control unit.
type fuel pump, and is injected from injectors into allThe crank angle sensor converts the crank
angle,
cders. The injectors are activated by signals fromthat is, engine turning state into an electric signal
tk, engine control unit, and the amount of fueland sends it to the engine control unit.
injected is determined according to the drivingThe engine control unit, based on these signals,
conditions.determines the basic activation timing of the
injec-The intake air passes through the air flow sensor,
tars. The amount of intake air is determined by the
throttle body, air intake plenum and intake manifold,degree of opening of the throttle
valye,, and during
and finally enters the combustion chamber. The airengine idling, the amount of intake
arr IS regulated
flow sensor detects the amount of air flow and
by the idle speed control servo.converts this data to electric pulse signals that are
EGR temperature sensor (California) 7
Waste gate solenoid valve <Turbo>
Purge control solenoid valve
EGR control solenoid valve <California>Fuel pump relay
Control relay
Air conditioner relay
Diagnosis output
Ignition coil
Control relay (Fuel pump drive
signal)Vehicle speed
SensorIgnition switch “ST” terminal
Ignition switch
‘IG” terminal
Air conditioner switch
Power steering
switch
Inhibitor switch
<A/T>Idle speed
ontrol servoFast idle
air valve
-Throttle
&r -kilo m-i&inn’Power transistorleturn to-
uel tank- Fuel from
Coolant temperature sensor
Coolant temperature switchFuel-pressure
control valve
<Turbo>Detonation sensor <Turbo>
4

14-14
.._~- ---.FUEL SYSTEM
- Sensors
SENSORSRlUGENERAL DESCRIPTION
The types and functions of the sensors are as listedsend corresponding signals to the engine control
below. These sensors detect engine conditions and
unit.
SENSORSFUNCTION
AIR FLOW SENSOR
fSenses the intake arr volume with a Karman vortex flow meter.
INTAKE AIR TEMPERATURE
SENSORSenses the Intake air temperature (temperature of air at
the point of entry into the air cleaner).I
BAROMETRIC PRESSURE
SENSORISenses the barometric pressure faltrtude) wrth a
semiconductor diffusion type pressure sensor.
$;;OOf;T TEMPERATURESenses the engine coolant tern
THROTTLE
POSITISenses the throttle
tI
IDLE POSITION SWITCHSenses whether or not the accelerator pedal is being
operated with a contact switch.
Senses the top dead center on compression stroke of
NO. 1 and No. 4 cylinders with an LED and photo diode pair.
CRANK ANGLE SENSORSenses the crank angle of each cylinder with an LED
and photo diodepair.
T
OXYGEN SENSORSenses
actrvation of the air con
POWER STEERING OIL
PRESSURE SWITCHc-lSenses the power steering ‘load with a contact switch.
IGNITION SWITCHSenses ON/OFF
posrtion of the ignition switch.I
Senses engine cranking.
,
IGNITION TIMING
ADJUSTMENT TERMINALWhen this terminal is shorted, the ignition timing and idle
speed control servo is set in the adjustrng mode by the enginecontrol unit.
INHIBITOR SWITCHSenses the *P” and “N” positthe automatic transaxle.Senses.
by pieto-electric element,. cylinder block
vibrations that occur when there ISengineknocking.
CONTROL RELAY
(Fuel pump drive signal)
lFnorne ianitron sianal!Senses ignrtton coil prIman/ voltage.

FUEL SYSTEM - Sensors
CRANK ANGLE SENSOR
II
DiscSensor
The crank angle sensor is mounted on the cylinder
head and is directly coupled to the intake camshaft.The crank angle sensor consists of a disc -and a
sensor unit.
Mu0499Slit for
crank anglesensor
Photo diode
LED
The disc, made of metal, has four slits located 90 degrees aparton its periphery and two slits located 180 degrees apart inward
of the four slits.
-The inner slits are used by the top dead center sensor
th,detects the top dead center of the No.
1 and No. 4 cylinders,
and the outer four slits are used by the crank angle sensor that
detects the crank angle. The disc is positioned on the sensor
shaft and rotates as a unit with it, being turned by the intake
camshaft.The sensor unit has two
LEDs and two photo diodes, used’to
detect the crank angle sensor slits and the top dead center
sensor slits.
The disc rotates between the
LEDs and the photo diodes. Each
time a slit comes between a LED and photo diode pair, the light
emitted by the LED reaches the photo diode by passing
through the slit.
Sensor unit
I I1
Power supply
I
Engine control untt
r
Crank angleslgnal

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,
14-24FUEL SYSTEM - Sensors
POWER STEERING OIL PRESSURE SWITCHEngine control unit
Power steering oil
pressure switchBattery
voltage
6FUO5OtIWhen the steering wheel is turned and the oil
pressure of the power steering oil pump increases,
the power steering oifpressure switch sends an ON
signal to the engine control unit. The engine control
unit detects the oil pump load with this signal andactivates the idle speed control servo to control
theidle speed. Specifically, it prevents the idle
speecfrom dropping due to oil pump load, thus
ensuringstable engine idling.IGNITION
SWITCH
1IBattery
Ignition
switch
Starter motor
aS terminalcontrol unit
6FUO762The signal indicating that the ignition switch is ON,
OFF or cranking (ST) is input to the engine control
unit.
When the ignition switch ON signal is input to the
engine control unit, the unit energizes the control
relay coil to supply power to the sensors and
actuators.When the ignition switch ST signal is input to the
engine control unit, it determines that the engine
iscranking and controls the fuel injection rate,
despeed control servo, ignition timing, etc. for
-mum cranking conditions.