CDI driving mode, function

P07.16-3308-09

Shown on code (I01) Air conditioning Plus

1 Request for coolant fan motor

2 Request for charge air fan motor

3 Request for refrigerant compressor
(for code (I01) Air conditioning Plus)

4 Request for gear change

5 Request for indicator and warning lamps

6 Crash signal

7 Request to ESP control unit

8 Status of gear selection

9 Request for preheating

10 Accelerator pedal position

11 Engine speed

12 Fill level for the fuel tank

13 Actuation of the fuel injectors

14 Actuation of quantity control valve

15 Regulation of rail pressure

16 Rail pressure

17 Residual oxygen content in exhaust

N2/7 Restraint systems control unit

N3/9 CDI control unit

N10/10 SAM control unit

N14/2 Glow output stage

N15/6 Automated manual transmission control unit

N23 Heater/air conditioning operating unit
(for code (I01) Air conditioning Plus)

N47-5 ESP control unit

S41/1 Oil pressure switch

Y74 Pressure control valve

Y76/1 Cylinder 1 fuel injector

Y76/2 Cylinder 2 fuel injector

Y76/3 Cylinder 3 fuel injector

Y94 Quantity control valve

CAN Controller Area Network (data bus/CAN bus) (CAN)

LIN A Local Interconnect Network CDI (LIN A)

18 Boost pressure

19 Charge air temperature

20 Fuel temperature

21 Coolant temperature

22 Oil pressure

23 Fuel pump actuation

24 Suctioned in air mass

A1 Instrument cluster

B2/5 Hot film mass air flow sensor

B4/6 Rail pressure sensor

B5/1 Charge pressure sensor

B11/4 Coolant temperature sensor

B17/8 Charge air temperature sensor

B37 Accelerator pedal sensor

B50 Fuel temperature sensor

G3/2 O2 sensor upstream TWC

L5 Crankshaft position sensor

M3/3 Fuel pump with fuel tank sensor

M3/3b1 Fuel tank sensor

In driving mode differentiation is made between the following driving conditions:

 Idle speed

 Part load

- Quantity mean value adaptation

- External quantity intervention

 Full load

- Limitation of the full-load injection quantity

- Maximum engine speed limitation

- Overheating protection

 Sliding operation

 Shut-off control

 Safety fuel shutoff

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Idle

Idle speed control keeps the idle speed constant, even during load requests, such as for the drive position selected or for a switched on refrigerant compressor (A9).

For this purpose, the CDI control unit calculates the target engine speed and performs a target-actual value comparison. Accordingly, the CDI control unit controls the rail pressure via the quantity control valve and the injection timing via the fuel injectors. Rail pressure and injection time determine the fuel injection quantity.

Partial load

One understands partial load as the driving situations between neutral and full load. For an engine running at its operating temperature the lambda control ensures optimum exhaust emission values in partial-load range.

The fact that in neutral and partial-load range injection is not made at the maximum pressure of 1650 bar means that in these load ranges a pump element for the high-pressure pump switches off (element shutoff). Thus the power absorption capacity of the high-pressure pump is reduced.

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Quantity mean value adaptation:

The quantity mean value adaptation is a learn function of the CDI control unit. Using readings from the hot film mass air flow sensor and from the O2 sensor upstream of TWC the exhaust gas recirculation rate is corrected so that the emission values do not deteriorate due to the fuel injector and hot film mass air flow sensor tolerances.

External quantity intervention

With external quantity intervention, the engine torque is reduced (e.g. for a shift operation) by the CDI control unit.

A reduction of the engine torque takes place through reduction of the injection quantity.

The following information is read in for this via the CAN from the CDI control unit and evaluated:

 Shift operation from automated manual transmission control unit

 Regulation from ESP control unit

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Full load

Limitation of the full-load injection quantity

The CDI control unit limiteds the injection quantity for full-load operation in order to minimize smoke formation in the exhaust.

If a fault in boost pressure control is detected, the full load injection quantity is also reduced.

Maximum engine speed limitation:

To protect the engine and drive train, the engine speed is limited by switching off the fuel injectors to 4500 rpm

Overheating protection:

The overheating protection protects the engine from thermal overload.

At a too high coolant temperature the injection quantity is reduced according to a performance map by the CDI control unit.

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Overrun mode

The braking effect of the engine in the overrun mode is increased and the fuel consumption is reduced by means of the overrun fuel shutoff.

The CDI control unit switches the fuel injectors off depending on the coolant temperature and engine speed. The rail pressure is also lowered.

The CDI control unit compares the following input signals to recognize deceleration mode:

 Status of the accelerator pedal

 Engine speed

 Vehicle speed

As soon as the accelerator pedal is actuated the fuel injectors are switched on again and the rail pressure increased.

Shutoff control

For terminal 15 off actuation of the fuel injectors by the CDI control unit stops. Furthermore actuation of the fuel pump with fuel level sensor is stopped by the SAM control unit.

Safety fuel shutoff

If the restraint systems control unit sends a crash signal, the SAM control unit switches off the fuel pump with fuel level sensor.