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NG 900/9-3 Throttle Body

583 bytes added, 18:20, 4 November 2009
==Overview==
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.Figs. 1 and 2[[File:90093_TB_1.jpg|thumb|Fig. 1 - Throttle Body Overview]][[File:90093_TB_4.jpg|thumb|Fig. 2 - Throttle Body]]
===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 [http://pages.infinit.net/mlbriand/saab/iac/page1.html| Michel Briand's Cleaning Directions]. Fig. 3[[File:90093_TB_3.jpg|thumb|Fig. 3 - Idle Air control Valve]]
===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. Fig. 4[[File:90093_TB_2.jpg|thumb|Fig. 4 - Coolant Connections]]
===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.Fig. 5[[File:90093_TB_6.jpg|thumb|Fig. 5 - Throttle Body Cleaning]]
===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.Fig. 6[[File:90093_TB_8.jpg|thumb|Fig. 6 - Throttle Body]]
===Throttle Body Connections===
Numbers correspond with labels in Fig. xx7
1 - Crankshaft ventilation hose (PCV)
2 - Air Pressure sensor (MAP)
4 - Turbo bypass valve (BPV)
5 - Evap emission system purge valve
6, and 7 - IAC valve hoses8, and 9 - Coolant hoses  [[NG900/9-3_Vacuum_Lines| Vacuum and PCV Lines]][[File:90093_TB_5.jpg|thumb|Fig. 7 - Throttle Body Connections]]
===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.Fig. 8[[File:90093_TB_7.jpg|thumb|Fig. 8 - Throttle Body Bottom View]]
==Part Numbers==