STAG-4 plus


The smallest construction – Full of possibilities in its class

Miniaturized Microprocessor Sequential Gas Injection Controller

Miniaturized Microprocessor Sequential Gas Injection Controller STAG-4 Plus has evolved from the tried, tested and reliable system STAG-300 Plus. The modernized controller is fitted with updated software with an additional 3D graphical map, which allows the precise control of gas injection, depending on the rotational speed of the engine.


The device offers the option of additional manual adjustment of the operating parameters, depending on the temperature of the injected gas, as well as a gas injector warm-up option. The controller software upgraded by adding accurate dosing functions for gas injection means that the cars with a system based on the STAG-4 Plus controller meet Euro 5 exhaust emission standards.


The controller is designed for all cars fitted with petrol engines with 1 to 4 cylinders, including a Valvetronic throttle less intake system (used e.g. in BMW engines), turbo, full group and sequential and semi-sequential petrol injection. The petrol injection emulator embedded in the controller is terminated with a Europe/Bosch type connection. STAG-4 Plus supports the AcGasSynchro software.


The advanced production technology ensures the reliability of STAG-4 Plus.

• Aluminium watertight housing.
• Build-in sequential petrol injection emulator.


Functional Characteristics
• Maintaining the key operating parameters of the engine:
  power, torque at the same level as for petrol fuelling.
• Automatic switching to petrol in the case of the lack of gas.
• Automatic switching to gas fuelling.
• Meets Euro 5 exhaust emission standards.
• Reminder to check the gas system.
• Accurate dosing of gas, depending on the rotational speed of the engine.
• Allows for the running on gas within the entire engine load range.
• Imperceptible moment of switching to gas fuelling.

Installation and Calibration

• Intuitive calibration of the controller.
• Setting air/fuel mixture ratio based on the information about petrol injection timing.
• Automatic adjustment of gas temperature and pressure.
• LPG/CNG compatible.
• Improved compatibility with (sequential, full group and semi-sequential) fuel systems.
• Controller is compatible with all gas reducers and injectors.
• New CNG algorithms.
• Gas injector connections compatible with most commercially available injector rails.


Software Functionality
• 3D graphical map – adjustment based on RPMs: graphical and digital visualisation.
• Detailed view of operating parameters on the oscilloscope.
• Setting extra-injection cut-off thresholds.
• Gas injector warm-up option.
• Engine RPM signal filter.
• Standard and turbocharged engines.
• New "Injection Control Type” option – permits the engines with a full group control to be fitted with e.g. a Valtek 3 Ohm type
   of injector.
• Mazda leaning option.
• Option of manual adjustment of operating parameters.
• Option of additional gas injector correction.

Warranty: 3 years - 2 years from the date of installation and not longer than 3 years from the date of manufacture


Year of production Number of cylinders STAG-4 PLUS
1990 and older 3 or 4 recommended
1991-2002 3 or 4 recommended
2003 and newer 3 or 4 recommended STAG-300 Premium

Selection of STAG-4 Plus Controller depending on the year of manufacture of the car equipped with a multi-function electronic petrol injection.



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