Mitsubishi Stealth 1994 Import Service Manual page 577

MULTIPORT FUEL INJECTION -
IDLE AIR CONTROL MOTOR (STEPPER MOTOR TYPE)
Ball beanng -fTbMagnetlc rotor
Throttle bodv seat
OPERATION
l 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.
The servo valve is opened or closed bly operating the stepper motor in the speed control servo in normal or
reverse direction.
The battery power is supplied to the stepper motor through the MFI relay. As the engine control module
turns on power transistors in the module one after another, the stepper motor coil is energized and the
motor rotates in normal or reverse direction.
TROUBLESHOOTING HINTS
Hint 1: If the stepper motor step increases to 100 to 120 steps or decreases to 0 step, faulty stepper motor
or open circuit in the harness is suspected.
Hint 2: If the idle air control motor harness and individual part checked good but the stepper motor steps are
out of specification, the following faults are suspected.
(1) Poorly adjusted reference idle speed
(2) 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.)
Ball bearing
On-Vehicle Inspection of MFI Components
Engine control module connector
connector
connector
control module