Air Circulation System
23
For this reason, in both engine versions, the required
vacuum is produced by a suction jet pump and, if
necessary, additionally by an electrical vacuum pump.
The suction jet pump is connected in parallel with the
throttle valve part upstream and downstream of the
throttle valve. The branched air flow drives the suction
jet pump. An extreme case is that of cold starting. For
example, when the catalytic converter is heating up, the
throttle valve is wide open.
In this case, the vacuum produced by the suction jet
pump is not enough to sufficiently evacuate the brake
servo. The Brake Booster Pressure Sensor G294 is
connected to the line to the brake booster and transmits
its values to the Engine Control Module J623 (ECM). In the
ECM (map controlled), the Brake Booster Relay J569 and
the Brake System Vacuum Pump V192 are activated until
the required vacuum is present.
Secondary Air Injection (AIR)
Pump Relay J299
Fuel Tank
Exhaust Flap
Exhaust Flap
Exhaust Flap Valve 1 N321
Vacuum Reservoir
Engine Control Module (ECM) J623
Engine Control Module (ECM) 2 J624
A
B
377_025
Summary of Contents for 4.2-liter V8 FSI
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