The present economic situation and the need to reduce exhaust emissions has boosted a market expansion for bi-fuel vehicles - capable of running on LPG or natural gas (CNG) and gasoline - that are now available in a broad variety of models.
Bi-fuel vehicles can switch between the two types of fuel thanks to electronic control units capable of controlling fuel injector opening or closing and adjusting injection timing to suit current fuel selection, whether gasoline or LPG (or CNG). MTA developed a specific ECU named DGI800 for this application. It is an electronic microprocessor system providing total management of a GPL(or CNG) fuel system, which also incorporates solenoid valve piloting, switching and emission control capabilities. The DGI800 is capable of managing the gas injectors from major car makers currently available in the market, for up to 8-cylinder engines. In addition, it ensures full compliance with car makers’ specifications in terms of drivability, responsiveness at full power, consumption, emissions and safety rules in force. As a matter of fact, the DGI800 system has been designed for total safety with internal relays that cut off power to the solenoid valves in the fuel system in the event of sudden power failure, missing engine rpm signal or pressure drop to prevent fuel leaks, and switch to gasoline operation. For correct operation of its internal control algorithms, the ECU interfaces with several outputs, such as engine rpm signals, injectors, oxygen sensor, pressure sensors, temperature sensors and fuel level sensor. The ECU features an input, normally connected to an external in-cab switch, for the driver to switch manually between fuels. The DGI800 incorporates an emulation system for up to 8 gasoline injectors that keeps it from entering the diagnostic mode when running on LPG or CNG, as well as a dedicated spark advance control system for CNG operation. Lastly, a serial communication line enables DGI800 to interface with an external tool installed on a PC that provides step-by-step setup and tuning instructions during installation.