CDI driving mode, function

The basic tasks of Common-Rail Diesel Injection (CDI) in driving mode include the provision of an engine torque, which corresponds to the accelerator pedal position. At the same time, the maximum smooth running characteristics at low fuel consumption and low exhaust gas emissions should be guaranteed. For this purpose, the CDI control unit (N3/9) must match the Electronic Diesel Control (EDC) and the air and exhaust system to one another according to the performance map data stored.

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CDI controls the following functions via the CDI control unit (N3/9) in driving mode:

 Quantity control

 Charging

 Emission control, with Code (MF8) Low-emission engine as per EU3 Group 3 or with Code (MF4) Low-emission engine as per EU4 Group 3

 Shutoff of the refrigerant compressor (A9), with Code (HH4) Automatic air conditioning or with Code (HH9) 'Tempmatic' regulated air conditioning

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For this purpose, the CDI control unit (N3/9) reads in the following variables from the associated components:

 On vehicles with Code (MF4) Low-emission engine as per EU4 Group 3, the intaken air mass and its temperature via the hot film MAF sensor (B2/5) and the integrated intake air temperature sensor (B2/5b1).

 The actual rail pressure via the rail pressure sensor (B4/6).

 The actual boost pressure via the boost pressure sensor (B5/1), the pressure sensor downstream of the air filter (B28/5) and the charge air temperature sensor (B17/9).

 Coolant temperature via the coolant temperature sensor (B11/4).

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 Accelerator pedal position via the pedal value sensor (B37/3).

 The fuel temperature via the fuel temperature sensor (B50).

 On vehicles with Code (MF4) Low-emission engine as per EU4 Group 3, the residual oxygen content in the exhaust gas via the O2-sensor upstream TWC [KAT] (G3/2)

 Engine speed via crankshaft position sensor (L5).

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In addition, the CDI control unit (N3/9) communicates with the following control units via the Control Area Network bus Class C (engine compartment) (CAN-C) to obtain information on further variables:

 With the instrument cluster (A1) as the interface with the Control Area Network bus Class B (interior) (CAN-B), in order to be able to process a set winter tire maximum speed or activation of the dynamometer test mode Electronic Stability Program (ESP), for example.

 On vehicles with transmission 722.6 with the ETC [EGS] control unit (N15/3), in order to receive information on the gear actually selected (actual gear engaged), for example.

 On vehicles with transmission 722.6, with the electronic selector lever module control unit (N15/5), in order to receive the information selector lever position "P" or "N", for example.

 With the ESP control unit (N30/4), in order to receive the wheel speeds, for examples.

 With the EIS control unit (N73) as the interface with the CAN-B, for example, on vehicles with Code (HH4) Automatic air conditioning or with Code (HH9) Tempmatic regulated air conditioning, to receive the switching status of the AC system.