223002883 - E5032 METHANE ENGINE ELECTRONIC MANAGEMENT - DESCRIPTION (BIPOWER)

Description

The petrol fuel system is managed by a control unit, which controls both the ignition and the fuel injection.The methane fuel system is managed by another control unit which controls the methane injection and the logic for the methane/petrol supply changeover, which takes place automatically or manually via the specific changeover button located on the dashboard.The two control units are connected to each other via the CAN: this permits optimum engine management under all operating conditions and with any type of fuel supply.

On the basis of the signals received from several sensors, the two control units, which share signals from some sensors, control the respective connected actuators, managing the following system:

• petrol supply
• methane supply;
• air supply system;
• engine cooling;
• fuel vapour recirculation;
• control of combustion - Lambda sensors;
• control of exhaust with catalytic silencer.

This version of the system also includes the EOBD (European On Board Diagnosis) system - conforming to Directive 98/69/CE (EURO 3) - permits continuous diagnosis of the car''s components relating to emissions, and by the special (amber yellow) ''injection system/EOBD failure'' warning light coming on, indicates any deterioration of these components.

Among other things, the system diagnoses:

• the catalytic converter, which in the case of a malfunction does not convert the pollutants produced by the engine;
• the Lambda sensors (oxygen sensors);
• the lack of combustion, so unburnt fuel reaches the catalyzer where the thermal conversion reactions cause a sudden increase in temperature, damaging the catalyzer.

The methane system is additional to the basic system, and does not alter the operation of the basic system under any operating conditions.The specific control unit manages the methane injection, of the phased sequential type, and the activation of the gas (methane) cut-off solenoids, and also fuel pump deactivation;The injection is implemented directly by controlling the specific methane system injectors. The ignition advance is regulated by sending to the ''basic'' engine management control unit the change in advance to be added to that applied during operation on petrol. This communication takes place via the CAN.The methane control unit uses the methane pressure and temperature sensor on the manifold to correct the injection times, thus controlling the exhaust emission values, which come within the limits of the EURO3 - EOBD regulations.If the control unit identifies a significant fault (e.g. to the methane injectors), an automatic changeover to petrol takes place, with the relevant indication via the warning light in the instrument panel.If, on the other hand, the unit identifies a minor fault, this is indicated but the fuel supply remains methane.All the other engine control functions, including ignition advance, are left to the ''basic'' engine management control unit.

The engine normally runs on methane.

if the methane runs out, the system automatically switches over to running on petrol and the appropriate warning light comes on. Once the methane has been refilled, the system automatically switches back to running on methane.

During starting and after refilling with methane the engine continues to run on petrol for several seconds to ensure that the pump, the injectors and the specific ducts are working properly.

The special switching button makes it possible to switch manually to running on petrol: in such a case both the green LED on the button and the special warning light come on.By pressing the button again, methane operation is restored.

the manual switching from petrol to methane and viceversa should not be done whilst starting the engine. This also occurs only if the engine rpm is lower than 2000 rpm.

For more details, especially on methane operation, see    See descriptions 1058 GAS CIRCUIT.The system is controlled by means of two relays located in the engine compartment. The supply lines for the engnie management control unit and the various system components (sensors and actuators) are protected by a special fuse, also located in the above mentioned box.Two relays and a fuse especially for the methane system are located outside the actual control unit.