All car manufacturers have to comply with increasingly demanding norms of emission of pollutants, especially since they want increase performance while reducing consumption.
The main solution that can guarantee such a result is the fuel injection option, directly to the combustion chamber, technique applied some time now in diesel engines.
In new engines entire process is controlled by the engine management with respect to time and amount of injection. In this way achieve better mixing of the fuel with air, while ensuring and reduce energy loss as heat.
The injection start, the injection path and the fuel spray form also affect the emission of harmful substances. The start spraying mainly indicates start burning. A spraying starting slower than the predetermined time, results in the NOx emission reduction (nitrogen oxides). If spraying started more slowly, then it increases the emission HC (hydrocarbons).

Technological advances in modern cars allows the electronic control of most systems, this is the most practical, economical and efficient solution. One of the major applications of electronics in today's vehicles to the injection system and engine ignition system. A better function can be achieved by controlling the spray principle directly to the nozzle.
The injectors in most new oil injection systems controlled electromagnetically by the control unit are disposed above the engine combustion chambers, to ensure uniform formation and good distribution of the mixture in the various cylinders.
The spray hole at the needle creates a tapered spout that ensures the conversion of fuel into micro- particles. To ensure accurate dosage, the mass of the needle / nozzle of the injector and the housing is very small, allowing the duration of opening and closing to be significantly less than one millisecond (ms).
All the above can ensure a uniform spray and proper operation of spraying, but often wear injectors changes the behavior of the vehicle with serious effects on driving performance, but also to pollutants. This creates requirements for cleaning and possibly repair the injector in some cases.