| The throttle body controls the flow of air into the intake. While
driving, air flow is controlled by the throttle plate. At idle, through
the electrically controlled IAC valve. The throttle body also has
inlets for hoses from the evap. emission system purge valve,
from the crankcase ventilation system (PCV), and vacuum lines leading the
the manifold air pressure sensor (MAP), the fuel pressure regulator (FPR),
and the turbo bypass valve (BPV). Note: hose connections for the
non-turbo version of the engine, and later 9-3 models are different. |
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Idle Air Control Valve
The IAC valve is a solenoid controlled valve which regulates the flow
of air into the engine during idle. It may require cleaning every
few years, and more often on engines where the crankcase ventilation system
or the turbo leak an excessive amount of oil into the intake. For details
see Michel Briand's Cleaning
Directions |
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Engine Coolant Connections
Engine coolant circulates through a section of the throttle body by
way of two hoses connected to the engine, to help prevent freeze up during
winter. |
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Cleaning and Lubrication
The inside of the throttle body may need cleaning every few years around
the throttle plate. The throttle arm springs and bushing can stick
and may require lubrication, and the throttle position sensor (TPS) can
wear out. The tar around the circumference of the throttle plate
is from the same source as the IAC valve contamination. |
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Throttle Position Sensor
The TPS is a rotary potentiometer which indicates the position of the
throttle plate. With the connector unplugged, the resistance measured
between pins 1 and 3 should change gradually between 2.5k Ohms with throttle
plate closed, and 1.0k Ohms fully open. |
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Throttle Body Connections
1 - Crankshaft ventilation hose (PCV)
2 - Air Pressure sensor (MAP)
3 - Fuel pressure regulator (FPR)
4 - Turbo bypass valve (BPV)
5 - Evap emission system purge valve
6, 7 - IAC valve hoses
8, 9 - Coolant hoses
Vacuum & PCV Lines |
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Bottom View
The vacuum lines are connected into two chambers at the bottom of the
throttle body, which open into the intake manifold. Also note groove
for the gasket between the throttle body and the manifold. |
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Part Numbers
Idle Air Control Valve: 9127200 (SE Turbo, IAC valves on non-turbo,
"S" models are different)
Throttle Position Sensor: 8857195 ('94-'95)
4661062 ('96), 9181538 ('97-'98)
Intake Air Temp Sensor: 9174442
Coolant Temp Snsr: 9182270, (side of the engine)
Manifold Temp Snsr: 9177213, (under the fuel rail) |
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