Mitsubishi Eclipse Workshop Manual page 157

FUEL
-
On-vehicle Inspection
of
MPI
Components
13-89
o
o
|DLE SPEED CONTROL SERVO (STEPPER MOTORI
Engine
control unit connector
o
o
@
Harness side
connector
lffil
I r-b*lr'.(l
I
tIwt
Equipnrnt
side
oonn€ctof
-4-
ffi
ldle
speed
control ser\o
@
OPERATION
.
The intake air volume during idling is controlled
by opening or closing the servo valve provided in the air
path that bypasses the throttle
valve.
o
The servo valve is opened or closed by operating the stepper
motor
in
the speed control servo in normal
or
reverse direction.
o
The battery power is supplied to the stepper motor through the control
relay.
As the engine
control unit
turns
on power transistors
in the unit one after another,
the stepper motor
coil is energized and the
motor rotates in normal or
reverse direction.
TROUBIESHOOTTNG
HTNTS
i
Hint
1:
lf
the stepper motor step increases
to
100
to
1
20
steps or decreases
to 0
step,
faulty stepper motöi
or
open circuit in the harness is suspected.
Hint
2:
lf the
idle speed control servo harness and individual part checks have resulted normal but the
stepper motor steps are out of
specification, the following faults are suspected.
(l)
Poorly adjusted reference idle
speed
l2l
Deposit on the throttle valve
(3)
Air leaking into the intake manifold through gasket gap
(4)
Loose
EGR
valve seat
(5)
Poor combustion in the cylinder (faulty ignition plug, ignition coil, injector, low compression
pressure, etc.)
njHtrlILJHL,rITLJHL__rI
Hffiffiffi
O
o
o
o
Control
relay
NCKUP >-
@
Mitrublshi
MotoEcorporltion
Apr. 1991
FWUEg(}TO