Device for adapting the air/fuel metering system and the ignition system of an internal combustion engine to enable the engine to run with all normally available grades of petrol (gasoline) fuel

Claim 1

Device for adapting the fuel/air metering system and the ignition system of an internal combustion engine to enable the engine to run with all normally available grades of petrol (gasoline) fuel, with a fuel/air metering system capable of being switched over from a fuelair map for λ=1 (combustion with a stoichiometric ratio; operation with 3-way catalytic converter and λ sensor (oxygen sensor) with unleaded fuel) to a fuel/air map for λ≠1, with an ignition system with several pre-programmed ignition timing maps and a facility for switching over between timing maps, characterised in that, four ignition timing maps (s u , n u , s b , n b ) are programmed in the memory, one being suited for operation with premium unleaded fuel (s u ), one for regular unleaded fuel (n u ), one for premium leaded fuel (s b ) and a fourth for regular leaded fuel (n b ), and that the fuel/air metering system (1) can be switched over with a hand-operated switch (4) or a plug and an initial switch-over can be made between the two pairs of ignition timing maps s u /s b and n u /n b (switches 10,11), so that the air/fuel map λ=1 and the ignition timing maps s u and n u are available when the combustion engine is operated with unleaded fuel, and the air/fuel map λ≠1 and the ignition timing maps s b and n b are available when the engine is run on leaded fuel, and that a further automatic switch-over unit (14), which becomes effective after the first switch-over between the ignition timing maps, is provided, and this switch-over unit, depending on the position of the first switch-over (10, 11), switches over between the ignition timing maps s u and n u , or s b and n b , according to the output of at least one threshold sensor (18) for at least one operating parameter of the internal combustion engine.