CDI preinjection function

P07.16-2228-76

Functional diagram

B4/6 Rail pressure sensor

B11/4 Coolant temperature sensor

B17 IAT sensor

B28 Pressure sensor

B37 Accelerator pedal sensor

F1 Fuse and relay module
(model 163)

K40/7 Right front fuse and relay module (model 220)

L5 Crankshaft position sensor

N3/9 CDI control unit

N10/1 Driver-side SAM control unit with fuse and relay module
(model 211)

Y74 Pressure regulator valve

Y76 Fuel injectors

Y94 Volume control valve

Task

Reducing noise and pollutant emissions

 The quantity injected required by the engine is subdivided into the quantity of pilot injection and the quantity of main injection.

Function

Start of actuation

The start of actuation of the pilot injection is calculated in line with the operating point, with the following data being taken into account:

 last start of actuation of the main injection

 coolant temperature

 engine speed

 vehicle electrical system voltage

 Injection time

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Shutting off preinjection

The pilot injection is shut off in line with the operating point, if:

 the moment of preinjection is exceeded

 engine speed too high

 preinjection quantity insufficient

 main injection quantity insufficient

 inadequate fuel pressure in the rail

 if the engine is switched off

Calculating preinjection quantity

The quantity of pilot injection is calculated on the basis of :

 engine speed

 atmospheric pressure

 coolant temperature

 intake air temperature

 rail pressure

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The coolant temperature, intake air temperature and the atmospheric pressure are used for correcting the quantity of pilot injection. The now determined quantity of pilot injection is removed from the quantity of main injection, in order to determine, if there is a sufficient quantity for the following main injection.

The rail pressure is selected so high, that a minimum quantity can be injected.

If the quantity of main injection is insufficient, the pilot injection is shut off.