Fuel Supply, Low-Pressure Side

Fuel supply, low-pressure side

Fuel quality
The engine is designed to provide optimum performance and fuel consumption if unleaded unleaded fuel 93 octane (R+M/2). When fuel with 90 octane (R+M/2) is used, the engine's knock controller automatically adapts the ignition timing.

In order to make optimum use of the available space, the Panamera is equipped with a saddle step fuel tank with a capacity of approx. 21 Gals. (80 l) on the Panamera V6. This includes approx. 4 Gal. (15 l) reserve capacity.







The following systems and functions are identical with the Panamera S models
- Internal design of the fuel tank (low-pressure side of the RLFS)
- A demand-controlled electric fuel pump
- Fuel filter (lifetime filter in the tank)
- Fuel-pressure regulator (rel. fuel pressure approx. 80 psi/5.5 bar)
- Tank ventilation via active carbon filter
- Tank leakage diagnosis (LDP) for USA vehicles
- Tank vent valve (1)
- Positive crankcase ventilation (2) to intake manifold

The entry point for positive crankcase ventilation directly on the intake manifold has an electric heater to prevent freezing at corresponding temperatures and to therefore avoid the risk of excess pressure in the crankcase.







Tank ventilation
The fuel tank is aerated and vented exclusively via the active carbon filter, which acts as an intermediate storage device for any HC emissions. Regeneration of the active carbon filter takes place via the tank vent valve when the engine is running.

The active carbon filter is installed behind the fuel tank. The tank vent valve is located on the right next to the electronic throttle. When the engine is running, the system is vented by the tank vent valve to the intake system of the engine (below the electronic throttle directly into the intake manifold).

Leak detection pump (LDP)
The functional principle for tank leakage diagnosis (LDP) is identical to that of the Cayenne vehicles. The complete fuel tank system is checked for possible leaks using the positive pressure method. This takes place only when the engine is running. The LDP is an electro-pneumatic diaphragm pump which is supplied via the intake manifold vacuum. Evaluation by means of a reed contact switch located on the diaphragm takes place after the pumping phase.

Positive crankcase ventilation
On the V6 engine, positive crankcase ventilation is routed directly into the intake manifold on the left of the electronic throttle.

Control unit for electric fuel pump







Operating principle
The control unit (S) for the electric fuel pump is used for demand-based control of the fuel delivery rate (like for the V8 models).

Power supply
Terminal 30
Terminal 31
Control via DME with bidirectional PWM interface

Electric fuel pump
The speed of the electric fuel pump is regulated by the specified frequency (with limitation of the phase current).

Operating principle
The fuel pump control unit is installed on the right in front of the fuel tank and has the task of stepless control of the electric fuel pump. This control unit receives the setpoint speed of the fuel pump from the DME control unit via a bidirectional PWM interface and sends back diagnostic information.







Power supply
The control unit is connected to the vehicle electrical system voltage via terminal 30. Terminal 31 represents the connection to vehicle ground.

Control input
The output of the fuel pump is controlled by the DME control unit by a PWM control signal. This bidirectional PWM interface is also used for diagnosis of the control unit for the electric fuel pump. Diagnostic information is described in Guided Fault Finding.







Control of the electric fuel pump (EKP)
The speed of the electric fuel pump is regulated by way of the specified frequency within the power limits of the fuel pump (with limitation of the phase current) and independently of the vehicle electrical system voltage (voltage compensation). The pump motor is a 3-phase synchronous motor without position feedback and without sensor. Further diagnostic information on the PWM signal and diagnosis is described in Guided Fault Finding.

NOTE: The electric fuel pump must be operated only with the electric control unit.

Activation of the electric fuel pump via the door contact
As soon as the DME control unit switches to Sleep mode, it is awakened again via a CAN wakeup signal when the driver's door is opened on the current Panamera models. The electric fuel pump is then operated at maximum speed for a period of 2 seconds. The electric fuel pump cannot be activated as long as the DME is now active (without ignition on). After the DME has switched back to Sleep mode again, this process can take place a maximum of three times without the ignition being switched on. This limit is designed to protect the vehicle electrical system management. Door contact activation can be activated again for a further three times with ignition On/Off.







Activation when ignition is switched on
On the current Panamera models, the electric fuel pump is activated at maximum speed for 1 second when the ignition is switched on. This ensures rapid pressure build-up for a possible "fast getaway".