1990 MITSUBISHI ECLIPSE oil

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.

FUEL SYSTEM- Power Supply Control
Battery
L11The engine control unit controls the power
suv ’tcthe sensors, engine control unit and
actuate,A;the control relay.
-P
.
-p.Ignition switch
Inn yr
To air flow sensor,crank angle sensor,idle speed controlsetvo. injectors
Control relay
Relay controlFuel pump
controlIgnitionswitch signal
Enginecontrol
unit
I6FUOl’
Power Supply ControlWhen the ignition switch on signal is input, the
engine control unit energizes the control relay coil
L3to turn on the
S2 switch, thus supplying power to the
injectors, air flow sensor, idle speed control servo,
Fuel Pump ControlWhen cranking the’engine (ignition switch at the ST
position), the engine control unit energizes the
Lcoil to turn on the
S switch, thus activating the fuel
pump.While operating the engine (ignition switch at the
IGposition), the crank angle sensor signal is input to
the engine control unit, which energizes the
L,
etc.Approximately seven seconds after input of
theignition switch off signal, the unit turns off the
Sswitch.
control relay coil to keep the
SI switch on, thus
continuing to activate the fuel pump.
When the crank angle sensor signal fails to be
inputfor 0.6 second or longer due to engine stalling,
.,the engine control unit immediately turns
thz. 5switch off to stop the fuel pump as a safet)
precaution.

F
FUEL SYSTEM -Auto-cruise Control System'l4-61
AUTOCRUISE CONTROL UNIT
Je auto-cruise control unit incorporates a micro-computer which provides the set coast, resume,
acceleration, cancel, low-speed limitation,
high-speed limitation, overdrive OFF control, and
auto-
matic cancellation functions. The microcomputer
inputs signals from the vehicle speed sensor and
the switches, and outputs Control signals to the
actuator’s DC motor, the electromagnetic clutch,and the automatic
.transaxle (4 A/T) control unit in
accordance with the programming (software) of themicrocomputer.
CONTROL LOGIC BLOCK DIAGRAM
--
Auto-cruise control UnitIgnitionswitcha.-.
I
Input interface circuit
piz7q.f~~
I
L
Micro-
computer
jutput interface circuitIr--lI----
--7I IActuatorI
Electromagnetic
clutch coil
OD-OFF out-
put circuit
NC: Normally closed

FUEL SYSTEM- Auto-cruise Control System14-69
ni2nnncisv,“y’I”“.-
connectorDiagnosis Display Patterns and Codes
SELF-D’IAGNOSIS AND INPUT-CHECK FUNC-
TIONSSELF-DIAGNOSIS
When there is a cancellation of the auto-cruise control system
operation not intentionally made by the driver, it is possible to
determine which circuit or what operation caused the cancella-
tion of the auto-cruise control system by following procedures,
(1) Stop the vehicle with the ignition switch and MAIN switch
in the ON position.
NOTETurning OFF either the ignition switch or MAIN switch
erases the diagnosis data. Be sure to keep the ignition
switch and MAIN switch in the ON position until you finish
the inspection.
(2) Connect a voltmeter to the diagnosis connector of the
junction block and read the output code.
(3) Check the output code against the following table to isolate
the cause for cancellation of the auto-cruise control mode.
Output codes
Display
patterns
2 sec.
1.5 sec.I0.5 sec.3sec. id 3 sec.
L3o-l
-Jdrec.
Probable cause
Abnormal condition of actuator clutch coil drive system
Abnormal condition of vehicle speed signal system
tow-speed limiter activation
(The system is normal if it can be
reset.1
n
Automatic cancellation activated by vehicle speed reduction
(The system is normal if it can be reset.)
Control switch malfunction (when SET and RESUME
switches switched ON simultaneously)
Cancel switch ON signal input (stop light
switch, clutch
switch. or inhibitor switch input wiring damage ordisconnection or,occurrence of abnormality in circuitwithin control unit

Y 5-FUEL SYSTEM
- Auto-cruise Control System14-71ACTUATOR CONSTRUCTION
The actuator unit consists of a DC motor, a worm
gear, a worm wheel, a planetary pinion gear, a
magnetic clutch, and two limit switches.
The magnetic clutch consists of a magnetic coil
mounted to the actuator case and a clutch plate
connected to the ring gear of the planetary wheel
gear by a spring.The magnetic clutch is energized and deenergized
by the control signal supplied by the control unit.
The clutch transmits the rotation of the DC motor to
the selector drive shaft, and allows the selector
drive shaft to rotate freely with the ring gear
regardless of whether the DC motor is being
energized or not.
Internal construction
Clutch plate
Maanetic clutch coilI ^. ,Planetan/ pinionCircuit diagram
MAIN switch
%tn m.=ir
Auto-cruise control unit
7S&&or drive shaft
Worm gear03R0077
Cross-section of actuator installation
Actuator bracket

14-72
._FUEL SYSTEM
- Auto-cruise Control System
___ -ACTUATOR OPERATION
IF SET TO A FIXED SPEED
When the SET switch is set to the ON position, the
control unit causes current to flow to the actuator’s
electromagnetic clutch coil; the clutch plate is then
attracted, the ring gear of the planetary gear is
secured, and, at the same time, the path from the
ECU to the DC motor becomes conductive and the
DC motor begins to rotate at high speed.As shown in the illustration, the rotation of the DC
motor is transmitted to the worm gear
--, worm
wheel, sun gear (unified)
+ planetary pinion.
Because the ring gear is fixed at this time, the
planetary pinion revolves while rotating around the
sun gear, and, because the planetary pinions are
installed to the carrier, the carrier and the unifiedselectcr drive shaft and selector rotate.
Clutch plate
<
7 Limit switch
DC motorSelector
Magnetic clutch coil Magnetic clutch coil
Selector diive shaft
MAIN switchTrl
4sTn
aAuto-cruise control
unit07AOO11The selection of the direction (PULL or RELEASE) of the
selector rotation is performed by the reversal of the direction of
conductivity to the motor, and this is controlled by the ECU.
Current Flow in PULL Rotation
.(soiid-line arrows)
The control unit microcomputer output causes transistors
Tr,and Tr, to be turned ON. Then, current flows from transistor
Tr,to DC motor,‘transistor
Tr,, and ground. As a result, the DC
motor rotates in the PULL direction.
Current Flow in RELEASE Rotation (dotted-line arrows)
Microcomputer output causes transistors
Tr2 and Tr3 to be
turned ON. Then, current flows from transistor
Tr3 to DC
motor, transistor
Tr2, and ground, resulting in the DC motor
rotating in the RELEASE direction.
The electromagnetic clutch is controlled by the MAIN and
CANCEL switches. When the MAIN switch is in the
01\L.position, it keeps the clutch plate attracted under norm
conditions (i.e. where there is no cancel condition).