1990 MITSUBISHI ECLIPSE steering

FUEL SYSTEM -Idle Speed Control14-49
Servo ControlServo control includes feedback control and position
ontrol. In feedback control, the engine control uniti;onstantly calculates the actual idle speed, and if
the
value differs from the target idle speed, the unit
drives the stepper motor to adjust actual speed to
Feedback ControlWhile the engine runs at idle speed, the stepper
motor is activated to keep the engine speed at the
preset target idle speed by controlling the bypass air
volume.
The target idle speed that is optimum for each
operating condition (including air conditioner switch
ON/OFF) has been preset. This engine speed
feedback control is provided under stabilized idling
conditions and not when any of the following
conditions occur.
l When the vehicle is moving at 2.5 km/h (1.6
mph) or more.the target value. In position control, the idle speed
control
is adjusted to the target position to cope
with air conditioner and other load changes. Position
control is also performed when cranking the engine
and decelerating.
lWhen the idle switch is turned from OFF to ON,
and while the idle switch is in the OFF position.
lWhen the air conditioner switch is turned from
ON to OFF, or vice versa.
l When power steering oil pressure switch is
turned from ON to OFF, or vice versa.
l When the ignition switch is turned from ST to
IG, or vice versa.
l While the dash pot control is in operation.
lWhen the inhibitor switch is switched from “N”
range to “D” range or vice versa.
If-1Air conditioner switch
Idle speed
control servo
r------ -- -‘,
(N range)4* I-I
BI
8
IL -L
- !5ysr motor 1I
zIdle upIStepper motor 7Engine
PII2. I.1Coolant temperature
tL.---m--v--JJ
Engine speed
I6Fuo6oo
Servo Drive Steps
(1) If there is a difference between the target and actual idle
speeds, the servo is activated the number of angular steps
corresponding to the difference, thereby extending or
.retracting the pintle to control the amount of bypass air, and
adjusts the actual idle speed to the target value.
Difference between the target
and actual idle speed fpm6FUO699I
Time sec.
c
6FUO76!The sewo drive steps during idle speed feedback Control
van/ as shown at the left.

14-50FUEL SYSTEM- Idle Speed Control
SDeed adiustina screwI -Throttle valve
Lw-3O(-22) 0132) 30(86! 601140) 9ofl94)Coolant temperature
“C (OF)6FUO641
E94
72--2--I
Q--.-.-z
3201.000 --4-\-\
5P9.o%IIIaI L-2O(-41 Of3214Of104)801176)Coolant temperature
“C VF)6FU028E
-201-4) Of3214OI104180(176(2) When the engine coolant temperature is low, the fast idle
air valve together with the idle speed control
servoperated to supply an adequate volume of bypass
,.raccording to the engine coolant temperature.
Feedback Control at
Idle(1) Basic target idle speed
The basic target idle’ speed is preset as a map value
optimized according to the engine coolant temperature.
This speed is maintained to ensure stabilized idle speed.
(2) Idle speed while the air conditioner is being operated
When the engine coolant temperature is high with the air
conditioner switch in the ON position, the idle speed is set
higher than the basic idle speed.
,
ICoolant temperature “C VF)6FUO28:Position Control
When the steering wheel is turned or the air
conditioner switch is operated while idling, theachieve the target position, thus controlling the
engine load changes and consequently the idlebypass air volume and suppressing engine speed
changes. The engine control unit also activates the
speed changes sharply. Therefore, immediately
after detection of such a load signal, the engine
control unit activates the idle speed control servo toidle speed control servo to achieve the optimum
target position while cranking, driving and decelerat-
ing, according to the operating conditions.
Power steering oil
pressure switchIInhibitor
switch
IDash pot
concjition“D”
xl
rangeposition-
UP W-U
IAlPower
steeringposition-
UP.4~i~hnditioner
IIdle speed
control servor”--““IiiI
I
c
IEngine
I
I
1wuosu
-

FUEL SYSTEM -Idle Speed Control14-51
_ 0 (32)80 (175)Coolant temperature “C (“F)6FUO2653
ATarget position during operation
of the power steering systemIDLE CONTROL SERVO POSITION CONTROL WHEN THE
ENGINE IS IDLING
(1) Basic position
The basic position is preset as a map value Optimized
according to the engine coolant temperature. The idle
speed control servo is activated to conform to this position,
thereby maintaining the optimum idle speed.
This basic position of the idle control servo
diiectlycorresponds to the basic idle speed described earlier.
1II
0(32)
80(176)Coolant temperature
“C VW6FUO291Servo position
during operation of
the air conditioner
0(32)
80(176)Coolant temperature “C (“F)6FUO757
1L)760 (30)Barometric pressure mmHg
(in.Hg)BFUlOlC(2) Servo position during shift to “D” range
For models equipped with the automatic
transaxle.when
the position of the shift lever is anywhere other than the
“P” or “N” range, the servo position is increased in
proportion to the load of the torque-converter.
(3) Idle control servo position during operation of the power
steering system
When the power steering oil pressure switch is turned on
because the steering wheel is being turned while
thevehicle is stationary, the servo position is changed to
correspond to the increased power steering pump load.
(4) Servo position while the air conditioner is being operated
When the air conditioner switch is turned on, the servo
position is changed to correspond to the increased air
conditioner load.
(5) High altitude compensation
A correction is performed by increasing the opening of the
idle speed control servo to allow increasing bypass air flow
in order to compensate for the loss of intake air volume
(asmeasured by weight) caused by a reduction in intake air
density due to a drop in barometric pressure at increased
altitude.
(6) “Training” function
A “training” function that enters a value based upon the
engine rpm and the target rpm into the memon/,
andcorrects the servo position according to this value, is
provided in order to obtain an even higher degree of
precision of position control.

- -----.--..
14-76FUEL SYSTEM -Auto-cruise Control System
Ignition switch
IGI
9
RESUActuator electro-
Microcomputer
1 T 1
rn’Auto-cruise control unit
Autocruisecontrol switch
IGlMAIN
;FF -+++&Control unit
power supply
terminal voltage
03AO264NC: Normally closed
07*0040
AUTO-CRUISE CONTROL SWITCH
The auto-cruise control switch is built into the steering column
switch.MAIN SWITCH
The MAIN switch is an automatic reset type switch to turn ON
and OFF the power supply of the control unit.
COMMAND INPUT SWITCHES (SET and RESUME)
The SET and RESUME switches function to input the control
signals of the auto-cruise control system; both are the
automatic-reset type.
These switches are ON while pressed and OFF when released.
For the ECU’s input interface, each of the input terminals is
pulled up by the battery voltage; the terminal voltage is LOW
level
(OV) when the switch is ON, and is HIGH level (about 12V)when the switch is OFF. These voltage changes (digital
sig*)are input to the microcomputer as ON and OFF signals
o.:
switches.
.

.-_. -
17-8REAR SUSPENSION <4WD> - Geneal information
REAR SUSPENSION <4WD>GENERAL INFORMATION
Rl7BEThe rear suspension is a newly developed double
wishbone independent suspension with a toe-in
correction feature utilizing compliance of thebushing to external force, and provides
excellesteering stability and a good ride.
The special features of this suspension include
l Optimum adjustment of suspensiongeometry
l Optimum adjustment of alignment
change
0 Passive toe-in correction function
l Optimum combination of spring constant,
shock absorber damping force. andbushing characteristics
l Elastic support of the doubleanti-vibration croSsmemberl Improvement of straight-forward
motion stability
0 Improvement of cornering
stability
l Improvement of steerability
l Good balance ofride andsteering stability
( , , :l Low noise and
low vibrationCONSTRUCTION DIAGRAM
absorber
Trailing arm
.
12AC

. -.-REAR SUSPENSION
- Double Wishbone SuspensionDOUBLE WISHBONE SUSPENSION
CONSTRUCTION AND OPERATION17-11
R17GAAP1. Suspension
crossmember2. Upper arm
3. Lower arm
4.Axle housing5.Trailing arm
6.Middle jointLeft
Right
12AOO58
1.The suspension consists of a pair of lateral arms
centerline of the upper and lower arm ball joints
(upper arm (2) and lower arm
(3)) mounted on
as a steering axis.
the suspension crossmember
(1) and trailing
The trailing arm and axle housing are rigidly
arm (5). The lateral arms and axle housing (4) areconnected.
connected by the ball joints. The axle housing,The suspension geometry is basically deter-
that is, the rear wheel can rotate about the
mined by the layout of these components.
2. The trailing arm also has a middle joint provided closer to
the suspension crossmember. As it is connected by pin
(7)that runs through it vertically, parts (A) and
(B) can rotate
relative to the pin. The insertion of rubber body
(8) creates a
spring constant in the direction of rotation.

17-12REAR SUSPENSION - Double Wishbone Suspension
12AWY
lZAOOS!
When cornering. I.to the right
I Toe-inToe angle
ReboundBump-
PositiveCamber(to body)
- Camber to ground: 0
Bump
Semi-trailing typeThis middle joint is located exterior to straight line
(p’connecting the trailing arm end mounted on the crossmet
ber side with the axle housing (king pin).
Because of this arrangement, the momentary center
P(intersection of front member centerline
(0,) of the trailing
arm and line
(02) interconnecting the middle points of the
lateral arm mounting points) is positioned rearward of the
wheel center.
3. When the wheel is subjected to an external force acting
towards the rear or to a braking reaction, the force FR acts
as a moment about momentary center
P, causing the tire to
steer in the toe-in direction, thereby securing directional
stability of the vehicle.
While the vehicle is cornering, side force Fc acts on the
outer wheel from the inside and side force Fc’ acts on the
inner wheel from the outside. These forces work
moments about momentary centers
P and P’, respective,,
to cause the outer wheel to be steered toward toe-in and
the inner wheel toward toe-out: As a result, both wheels
are steered in the same direction as the cornering direction
of the vehicle. This results in under-steering to improve
cornering performance and stability.
4.The change in toe angle and camber to ground is kept small
for bumps or rebounds as shown at the left and this
contributes to steering stability while cornering.

-
REAR SUSPENSION -Double Wishbone Suspension17-13
Member supponbushingI
12AOO5
Upper arm
Link diagram of ordinarydouble wishbone suspension system
5. The suspension crossmember is mounted with the mem-
ber support bushing on the body. The input from the wheel
is first damped by the trailing arm and the bushings of the
lateral arms. It is then further damped by the member
support bushing. This dual anti-vibration construction
provides low vibration and low noise.
In addition, mounting of the differential carrier on this
crossmember decreases the natural frequency of the
crossmember, further damping vibrations.
The lower natural frequency of the crossmember allows
harder adjustment of the support bushing so that the
tendency toward oversteering of the suspension due to
side force, occurring during cornering can be reduced. This,
combined with understeering tendency by middle joint
.displacement described in (3) above, results in totally slight
understeering tendency.
Why this new rear suspension system is classified as a double
wishbone suspension
The new rear suspension is represented below by the diagram
as an aid to understanding its construction.
F-7-,12AOO33!A/ \
12AOO37Point A can rotate about rotary axis B-C and point
Dcan rotate about rotary axis E-C. The triangles ABC
and DEC can rotate like wishbone suspension
arms.When this is compared to an ordinary double
wishbone type suspension, it may be regarded asone with forward points
C, and C2 of the upper and
lower arms located at the same point. Thus, this
new rear suspension system is considered as a
double wishbone suspension system.