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FUEL
SYSTEM
AND
THROTTLE
BODY
5-3
INTAKE AIR SYSTEM
SECONDARY THROTTLE CONTROL SYSTEM
The secondary throttle control system (STCS) consists of the secondary throttle valve (STV), secondary
throttle valve actuator (STVA) and secondary throttle position sensor (STPS).
STV is installed in each throttle body. STVA and STPS are installed on the right side of the throttle body
assembly. The STV is turned by the STVA.
This system is designed to control the volume and the velocity of intake air so as to improve engine output
power. The system produces smoother and linear throttle response.
This is performed by opening or closing the throttle body intake port according to the gear positions and
engine rpm.
When the engine is running in a low speed range, the intake port is almost closed for controlled intake air
volume. This improves the effect to intake air flow pulsation so that the engine can output higher power in
this speed range.
As the engine speed grows faster, the intake port gradually opens for guiding the proper volume of air into
the throttle body so that the engine can produce the maximum power in each speed range.
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Secondary throttle position
, 0 sensor (STPS)
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Secondary throttle valve (STV)
Secondary throttle valve
actuator (STVA)