o-4GENERAL - Technical Features
BASIC CONSTRUCTION
The 4WD vehicles are equipped with
2.OL DOHC
16-valve turbocharged engine and incorporate new
technologies such as full time 4WD of center
differential type with viscous coupling differential
limiting for excellent running stability and excellent
Steering
l Light weight and compact rack and pinion
type for high steering response
l Tilt steering mechanism to give optimum
driving position
\driving across bad roads, and $-wheel independent
suspension for comfortable riding.
Adopted on
2WD vehicles are 2.OL DOHC 16-valveengine, MacPherson strut type front suspension
and torsion axle
typ.e 3-link rear suspension.
Rear suspension
l Self-aligning double wishbone type suspen-
sion for comfortable ride
(4WD)l Torsion axle type 3 link suspension for
outstanding driving stability
(2WD)l Negative chamber for outstanding steer-
ability during high speed driving
0 Anti-lift geometry for high stability duringbraking
lIntegral torsional bar type axle beam for
optimum roll stiffness (2WD)
\Front propeller shaft (3-piece
4-joint type)
lRobro joint to absorb lengthwise and angular
change and prevent transmission of vibrations.
(4WD)
IFront suspension
The front suspension of McPherson strut type
independent suspension system
l Under steer geometry for outstanding steering
stability
l Negative offset geometry for outstanding
stabil-ity at braking
0 Offset coil springs for comfortable ride
Brakes
l Cross piping dual type proportioning valvethat keeps balanced braking power even at
failure of the hydraulic system.
l Four wheel disc brake system for high
braking power.
GENERAL - Technical Featureso-5ENGINE
The engines are the transverse-mounted engine
especially for front-engine/front-wheeldrive orfront-engine/4-wheel drive models, the
2.OL DOHC
16-valve engine with high-performance, silent-
operation,low-vibration,low-noise,low-fuel-
consumption features, an engine that fully displays
the most
up-todate engine technology.
SPECIFICATIONS
Engine model
Displacement
cc (cu.in.1
h$xo$put (SAE net)Max. torque (SAE net)
ft.Ibs./rpm
4G63Non-Turbo1997(122)135/6000125/5000
4663Turbo1997(122)195/6000203/3000
FEATURESHigh performance and low fuel consumption
l The rocker arm reduces the valve-actuation torque as well as fuel consumption.
l Air-intake efficiency improved through the adoption of the optimum air-intake system layout.
l Improved response and fuel consumption has been achieved by electronic control multipoint
fuel injection.
l Water-cooled turbocharger.
Quiet operation
l Noise and vibration have been decreased by the adoption of roller rocker arms.
l Noise generated by the valve mechanism has been decreased by the hydraulic auto lash adjusters.
l Vibrations have been decreased by the adoption of bearing caps with beams which increase the
rigidity of the crankshaft support points.
-Serviceability
l Complete self-diagnosis functions.
l Enhanced reliability through the adoption of gold-plated connector terminals.
l Use of an auto tensioner achieves maintenance-free, automatic adjustment of timing belt
tension.
l Use of the auto lash adjusters achieves maintenance-free, automatic adjustment of valve clearance
.o The 2coil ignition system without a distributor supplies sufficient ignition energy even during
high speed operation.
-. ..- ,..__ _. I-., . . . . -. . “-Ix.. ...~‘,.;;&;,-*~;
CLUTCH- Clutch Control6-3
-
Inter-lock switchINTER-LOCK SWITCH
The inter-lock switch is a switch provided in order to prevent
sudden movement of the vehicle when the engine is star-ted.
BTAFTER YCTER
If the Clutch Pedal is Not Depressed:
Because the inter-lock switch is switched ON when
STABT
position, electricity flows from the cloil of the starter
relay, through the inter-lock switch, to ground. As a
?sult, the contacts of the starter relay separate,
vitching it OFF, and the starter motor is therefore
not activated.
IGNITION SYSTEMELECTRICAL - Engine Electrical8-25
I
Sensors
Engine control unitlgnltlon switch
Battery
11 IPower transfstor
hhP 1
Ilgnltion coil
C To tachometerTerminal for engine
speed detectton
6ELOO45The ignition system is a two-coil ignition system that
supplies sufficient energy for ignition up to high
speeds. This engine does not have a distributor
since the engine control unit directly activates the
power transistor for ignition timing control.
The functions and controls of the engine control unit
and various sensors that control the ignition timing
are described in the next chapter, IGNITION CON-
TROL SYSTEM.
This ignition system has two power transistors and
two ignition coils. Power transistor “A” controls the
primary current of ignition coil “A” to activate thespark plugs of the
No.1 and No.4 cylinders.
Similarly, power transistor
“B” controls ignition coil
“B” which activates the spark plugs of the
No.2 and
No.3 cylinders. In this way, spark plugs of two
cylinders are activated but actual ignition takes placeonly in the single cylinder that is on its compression
stroke, because the other is on its exhaust stroke at
that time.
Power transistors “A” and “B” are activated by
signals from the engine control unit, that controls
which cylinder is fired at what time.
8-26ELECTRICAL - Engine Electrical
No.:
4Signal unit for
, tachometer
71
x
No. 3
6EL0025
Capa &orCylinderNo. mark
6EL0057
To No. 1spark plug
To No. 4
spark plug
To No. 3spark plug
To No. 2spark plug
6EL005t
OC,IB, G
OC, IB, G IB, OC:IGNITION COIL
Two compact ignition coils of a molded type featuring
outstanding ignition performance are used.
Being a two-coil type, the ignition coil has a unit to supply
signals for the tachometer.
Specifications
itemsSpecificationsPrimary coil resistance
$20.86 at 20°C (68°F)
Secondary coil resistance
kR12.1 at 20°C (68°F)POWER TRANSISTOR
The power transistor is driven by a signal from the engine
control unit and turns the priman/ current of the ignition coil on
and off.
Terminal symbol
External connection
G
IB,
I&
Ground
Engine control unitEngine control unit
OGoc2Ignition coil terminal “2”
Ignition coil terminal “1”
SPARK PLUG
IEngineTypeGapI-
Non-turboBPR6ES-11WZOEPR-11RN9YC4
1.0-1.1 mm(.?39-.043 in.)I
0.7-0.8 mm(.OZB-.031 in.)A
-----. _-- ___ELECTRICAL
- Engine Electrical8-27IGNITION TIMING CONTROL SYSTEM
Air flow sensor
Engtne control unit
Intake air temp. sensor
Barometric pressure sensor
Engine coolant temp. sensorIdle position switch
:+
Top dead center sensor
Crank angle sensorVehicle speed sensor
;+Ignition switch “ST” terminal
Detonation sensor for
turbo engine only
4 Power= tranststor “B”P Ignition coil
109
_
I
1
12a”- To tachometer
Terminal for engine speed detection
Terminal for ignition,timing
and idle speed adjustment
6FUoE.45The ignition control system uses the engine control
consideration the operating conditions of the
en-unit, that judges which cylinder is to be fired at what
gine. The functions and controls of the engine
time based on the signals coming from variouscontrol unit are described in the following page.
sensors. The engine control unit activates the
The constructions and functions of the various
power transistors so that ignition occurs, taking into
sensors are described in GROUP 14.
8-28ELECTRICAL- Engine Electrical
IGNITION TIMING CONTROL
Reading of Input signallgnitlon power
distribution control
(selection of power
transistor actlvatlon)Control mode
I II II IControl mode
dectsion data
Basic energlzatlon
I’
Engine control unitPower
Powertranststor “A”tranststor “B”
6ELOO66The above block diagram shows the
fljnctions of the
engine control unit for ignition timing control.
One feature is that the engine control unit provides
ignition power distribution control which is neces-
sary because this engine is without a distributor, as
has been described earlier. By activating two power
transistors alternately, the primary current of two
ignition coils, one for the No. 1 and No.4 cylinders
and one for the No. 2 and No, 3 cylinders is turned onand
off. thus causing the cylinders to fire in the
order of 1, 3, 4, 2.
For ignition timing control, -optimum ignition timing.^--_
_. -.is determined by making preset corrections which
has been for engine coolant temperature, intake air
temperature an& other conditions of the ignition
advance angle that has been preset according to the
engine operating conditions. For vehicles with
tur=_.bocharger have a knocking control that corrects tl
ignition advance angle according to the presence or
absence of knocking.
The engine control unit also controls the primary
current energization time in order to secure stable
ignition energy.
These controls are explained in detail below.
--. .----- ---- --- ___. .-. ___.,.__
8-30ELECTRICAL - Engine Electrical
Ignition Advance Angle Control
While
cranking
Fixed angle(5”BTD.C)Engme coolantBarometnc‘-Intake air 1temperaturepressuretemperaturesensorsensor, sensor
Dunng normal operatlon4i+
Advance angle map valueEngine
coolantBarometricIntake airaccording to engine speed4and intake air volumetemperature- pressure__c temperature 4
correctioncorrectloncorrectton
Durtng ignition tlmmg adjustment
Fixed angle(5”BTDC)
c
=ower transistor
-$To ignition
coil
s
6EL0066The engine control unit has the ignition advance
angle value for all cylinder stroke intake air volumes
(engine load) and engine speeds stored in its
memory; this is called the basic ignition advance
angle. The control unit makes corrections in this
value according to the engine operating conditions
such as the engine coolant temperature, barometric
pressure (altitude) and intake air temperature to
obtain optimum advance angle for current engine
conditions. At the engine start and during ignition
timing adjustment, however, it is set to preset fixed
timing.
(1) WHILE CRANKING
When cranking, the ignition advance angle is fixed at
5”BTDC in synchronization with the crank angle
signal.(2) DURING NORMAL OPERATION
Basic ignition advance angle:
Map values that have been preset for all cylinder
stroke intake air volumes (engine load) and engine
speeds.Engine coolant temperature correction:
The engine coolant temperature sensor detects the
engine coolant temperature and when it is low, the
-ignition timing is advanced to improve driveability.
Barometric pressure correction:
The barometric pressure sensor detects the
barometric pressure and determines the altitude.
When the pressure is low (i.e. when the vehicle is at
a high altitude), the ignition timing is advanced to
secure maximum driveability.
intake air temperature correction:
The intake air temperature sensor detects the intake
air temperature and when it is low, the ignition
timing is delayed to prevent knocking in cold
weather. When it is high, the timing is also delayed
to prevent of knocking.
(3) DURING ADJUSTMENT OF IGNITION TIMING
When the terminal for ignition timing and idle speed
adjustment is shorted to ground, the ignition timing
is set at
5”BTDC in synchronization with the crank
angle signal, If the ignition timing does not agree
with the reference ignition timing of 5’BTDC, turn
the crank angle sensor to adjust the timing so that
the crank angle signal agrees with the reference
ignition timing. When the engine speed is approx-
imately 1,200 rpm or higher, however, the timing
advance is according to normal operation and
therefore this ignition timing adjustment is not
available.
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. .1-_ .---