Fully Sequential Fuel Injection

Fully Sequential Fuel Injection
In the fully sequential fuel injection system, each fuel injector is activated by its own output stage.

Fully sequential fuel injection offers the following advantages:

- Improved mixture preparation for each individual cylinder
- Adaptation of the injection timing to the relevant engine operating status (engine speed, load, temperature)
- Cylinder-selective injection correction under changing engine load conditions, i.e. during one operating cycle can vary the injection timing by means of post-injection, extending or shortening injection
- Cylinder-selective cutout is possible (e.g. in the event of defective cylinder coil)
- Diagnosis of each individual fuel injector is possible

These advantages of fully sequential fuel injection are gained because all cylinders are independently supplied with fuel.

Activation of each individual fuel injector by means of a separate output stage ensures that the presupply of the fuel is the same for all cylinders thus ensuring uniform mixture preparation quality for all cylinders. The presupply time is variable and is dependent on the engine load, speed and temperature.

In view of the fact that fuel injection only takes place once for each revolution of the camshaft the scatter of the fuel supply rate is low due to the component tolerances. Added to this, the idle quality is also improved as the energization and deengerization times at the fuel injectors are reduced. Fuel consumption is also slightly lower.

The injection timing can be corrected while driving as the result of sudden acceleration or deceleration. If the fuel injectors are still open, the mixture can be corrected at the valves that not have not yet injected fuel, are currently injecting fuel or have already injected fuel by means of short post-injection or correspondingly lengthening or shortening the injection timing. This achieves improved response characteristics of the engine.

Another important improvement is that in the event of one output stage failing, the engine can still continue operation on the remaining cylinders to the nearest BMW service workshop.