Audi A3 Sportback, Сервисная инструкция, Страница: 34 / 60

34
Tumble flaps
As the engine is operated in homogeneous-charge
mode only, tumble flaps are used to improve
mixture formation inside the engine. They are actuated:
–
to improve idling quality when the engine is cold
– to improve charging efficiency at engine start-up
– in overrun
– in homogeneous split mode (HOSP)
Engine
High-pressure rail Plastic flap with steel
shaft
High-pressure/low-
pressure fuel port
Pressure limiting
valve
Tumble flap actuator Activated charcoal
filter valve
ACF system with
double non-return valve
Throttle valve actuator
Intake air temperature sensor
332_058
Operating mode
HOSP Homogeneous split for rapid heating-up of the catalytic converter
Lambda value approx. 1.05
Intake manifold flap closed on one side (to enhance tumble effect)
Throttle valve wide open
Injection timing first injection approx. 300° before ignition TDC, second injection with a reduced amount
of fuel approx. 60° before ignition TDC
Ignition timing retarded, mixture ignites very late, exhaust valves already open, exhaust gas temperature
rises rapidly. The catalytic converter reaches its operating temperature rapidly.