Tetrafuel

The ECU represents the brain of the Flexfuel system, and it incorporates 32-bit microprocessors with state-of-the-art data processing and storage capacity. It is equipped with a modular hardware structure that adapts to all the various vehicle architectures, and with innovative management software that integrates all the functions of the SFS (Software Flexfuel Sensor) with the management of the CNG fuel.

This means that the user is provided with the advantages of the SFS and, at the same time, with the possibility to use natural gas.

The new software, called TETRAFUEL, was developed entirely by Magneti Marelli and employs a sophisticated calculation algorithm, exclusive and protected by many international patents. In this case, the control unit manages two fuel delivery systems in parallel, one with the liquid alcohol/gasoline/blend Flexfuel, and the other with the gaseous fuel.

The user can manually select the fuel to be used through a specific command, or allow the TETRAFUEL software to select it automatically, depending on certain conditions such as driving style, road conditions, etc. The calculation algorithm translated by the TETRAFUEL software was designed to limit fuel consumption and reduce polluting emissions.

This means that CNG is normally used, unless conditions occur that make it more cost-effective or necessary to use liquid fuel, such as, for example, a sporty driving style or roads with steep slopes that require greater power of the engine.

A special algorithm ensures the transition between liquid and gaseous fuel and vice versa in a totally fluid manner, without the driver perceiving any irregularity in engine torque delivery. Just like in the SFS (Software Flexfuel Sensor), in the TETRAFUEL software all engine and vehicle operating parameters are updated in real time depending on the fuel being used and, if liquid, on the alcohol/gasoline blend. This way, the engine always works in the manner best suited to the type of fuel used and guarantees optimal performances, consumption and driveability, even when CNG is used.

The fuel rail distributes fuel to the injectors. The TETRAFUEL system uses two different fuel rails, a single fuel rail for the liquid fuel that distributes gasoline, alcohol and the various blends, and a second fuel rail that distributes the gaseous fuel.

The fuel rails can be made in different materials (high-resistance plastic materials, stainless steel) depending on the construction characteristics of the vehicle, and stay intact even with the use of highly corrosive pure alcohol, especially when water is added to it. All the fuel rail functions stay the same under different operating conditions (temperatures, vibrations, etc).

The injectors ensure fuel delivery to the engine. The TETRAFUEL system uses two different sets of injectors: the first one can deliver gasoline, alcohol and the various blends, while the second one delivers the gaseous fuel.

Magneti Marelli produces the PICO and the new PICO ECO injectors, both designed to withstand the high corrosive power of ethanol.

A special configuration of the traditional PICO injector, together with the use of new materials offering special friction characteristics, has made it possible to produce an injector perfectly capable of effectively managing the delivery of CNG.

Magneti Marelli has developed injectors equipped with special nozzles that guarantee perfect fuel delivery under all environmental conditions and with any fuel

All this, combined with the control accuracy of software, allows the TETRAFUEL system to guarantee the highest engine and vehicle performances in terms of power and torque, fuel consumption, polluting emissions, and driving pleasure.

Thanks to the perfect complementariness of the injectors for liquid and those for gas, a perfectly smooth transition can be achieved between the liquid and gaseous fuel, so that the user perceives no discontinuity. Just like all the other components of the Magneti Marelli TETRAFUEL system, all the characteristics of the injectors stay the same under different operating conditions (temperatures, vibrations, etc.).

It is the load-bearing structure of the Tetrafuel system. In addition to ensuring constant and even air flow to the engine, it houses all the components that inject the liquid fuel with the different gasoline/ethanol blends and the CNG. It can be made in plastic or aluminium, depending on the construction needs of the vehicle, and all its functions stay the same under different operating conditions (temperatures, vibrations, etc.).

All the other components that make it possible to obtain the proper air/fuel mix needed by the engine are assembled on the intake manifold. Among these, the two different fuel rails together with the respective injectors (one for the liquid fuel, the other for the gaseous fuel), the throttle body, the various sensors and actuators, and the cold start system, in all its different versions, needed for the engine to run on E100 pure alcohol at low temperatures.

Its design combines excellent structural resistance, high permeability to air and a perfectly even air flow inside its various branches, thus ensuring balanced and efficient delivery of air to the engine. Its structural characteristics make it extremely effective in reducing engine intake and combustion noise. The intake manifold was designed to house the two fuel rails with the respective injectors, allowing the transition from liquid fuel to gaseous fuel and vice versa to take place with a totally even air/fuel blend reaching the engine.

This is an innovative cold start system that, thanks to the fuel being heated inside the fuel rail, allows vehicles equipped with TETRAFUEL to run properly even at low temperatures, when the engine runs on ethanol.

In the first-generation TETRAFUEL systems, the combustion difficulties of pure alcohol at low temperatures were dealt with by fitting an additional fuel delivery system that, when conditions required it, injected in the engine - at the same time as the pure alcohol - a certain quantity of gasoline contained in a small additional tank. This solution turned out to be expensive and quite ineffective in complying with the stricter and stricter emission limits set by the different international regulations. This is why Magneti Marelli, confirming its leadership in TETRAFUEL technology, developed an innovative system called ECS (Ethanol Cold System) that, through controlled heating of the fuel in the fuel rail, completely eliminates the additional delivery system found in the first-generation TETRAFUEL systems. The ECS (Ethanol Cold System), protected by many international patents, heats up the ethanol by means of two resistances positioned inside the fuel rail, which features a special internal geometry.

The pure alcohol heated up in this manner ensures optimized combustion in the engine; consequently, engine performances are adequate even at low temperatures, in terms of power and torque as well as in terms of fuel consumption and polluting emissions