IDLE AIR CONTROL MOTOR
DESCRIPTION
The idle air control motor (IAC) attaches to the
throttle body (Fig. 10). It is an electric stepper motor.
OPERATION
The PCM adjusts engine idle speed through the
idle air control motor to compensate for engine load,
coolant temperature or barometric pressure changes.
The throttle body has an air bypass passage that
provides air for the engine during closed throttle idle.
The idle air control motor pintle protrudes into the
air bypass passage and regulates air flow through it.
The PCM adjusts engine idle speed by moving the
IAC motor pintle in and out of the bypass passage.
The adjustments are based on inputs the PCM
receives. The inputs are from the throttle position
sensor, crankshaft position sensor, coolant tempera-
ture sensor, MAP sensor, vehicle speed sensor and
various switch operations (brake, park/neutral, air
conditioning).
When engine rpm is above idle speed, the IAC is
used for the following functions:
• Off-idle dashpot
• Deceleration air flow control
• A/C compressor load control (also opens the pas-
sage slightly before the compressor is engaged so
that the engine rpm does not dip down when the
compressor engages)
Target Idle
Target idle is determined by the following inputs:
• Gear position
• ECT Sensor
• Battery voltage
• Ambient/Battery Temperature Sensor
• VSS
• TPS
• MAP Sensor
REMOVAL
REMOVAL - 2.7L
(1) Disconnect the negative battery cable.
(2) Disconnect the IAC electrical connector.
(3) Remove the IAC mounting screws.
(4) Remove the IAC.
REMOVAL - 3.5L
(1) Disconnect the negative battery cable.
(2) Disconnect the air plenum.
(3) Disconnect the electrical connector (Fig. 11).
(4) Remove the mounting screws.
(5) Remove the IAC.
INSTALLATION
INSTALLATION - 2.7L
(1) Install the IAC to the throttle body.
(2) Tighten mounting screws to 5.5 N·m (49 in.
lbs.) torque.
(3) Attach electrical connector to the IAC.
(4) Connect the negative battery cable.
Fig. 10 Idle Air Control Motor
1 - THROTTLE POSITION SENSOR
2 - IDLE AIR CONTROL MOTOR
Fig. 11 Idle Air Control Motor
1 - THROTTLE POSITION SENSOR
2 - IDLE AIR CONTROL MOTOR
LH FUEL INJECTION 14 - 29
To Next Page
Loading...
