CDI main injection 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

Release the injection timing point and the injection period.

The quantity injected required by the engine is subdivided into the quantity of pilot and main injection. If the quantity of main injection calculated by the engine control unit is insufficient, no pilot injection takes place.

Function

The main injection is divided into two phases:

 Start of actuation

 Period of actuation

Start of actuation

The start of actuation of main injection is dependent on engine speed and on the quantity. It is corrected additionally dependent on the following sizes:

 coolant temperature

 intake air temperature

 atmospheric pressure

 Preinjection YES/NO

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Period of actuation

For the calculation of the period of actuation of the main injection, observe if a pilot injection has taken place.

Switching off main injection

The main injection is switched off in the following cases:

 engine speed too high (>4700 rpm)

 main injection quantity insufficient

 inadequate fuel pressure in the rail

 Engine switched off

 external quantity control (ESP)

 deceleration mode

Calculating main injection quantity

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

 engine speed

 atmospheric pressure

 coolant temperature

 intake air temperature

 rail pressure

 boost pressure

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The coolant temperature, intake air temperature and the atmospheric pressure are needed for correcting the quantity of main injection.If the main injection quantity is below a minimum quantity dependent on the rail pressure, no preinjection takes place.

In this case, only main injection is performed. If the quantity is then still below the minimum quantity, neither main injection nor preinjection takes place (deceleration mode).