SUBSTANTIATION OF FREE ACCELERATION METHOD FOR ELECTRONICALLY CONTROLLED FORCED FUEL INJECTION ENGINE IN THE PROCESS OF TESTING DIAGNOSTICS
The method of evaluating the operation conditions of a gasoline engine is discussed. The examination of carburetor engine acceleration gave evidence that dramatic increase of fuel supply with the purpose of shifting the engine into the free acceleration mode appears unreasonable since the free acceleration features are inevitably distorted due to the work of the acceleration pump. The replacement of carburetor engines with the forced fuel injection engines with electronically controlled fuel supply provides new opportunities for test modes implementation aimed at gaining diagnostic information due to the possibility of fuel supply control. Nevertheless, the free acceleration cannot be conditioned by the abrupt throttle opening because of the ambiguous influence of transient characteristics. This work contains the analysis of intake manifold processes taking place at different throttle positions and speed. It was revealed that the transient process is considerably influenced by control modes and the chosen calibrations. In view of the difficulties connected with theoretical investigation of the way the free acceleration method influences the output characteristics of ZMZ 4062.10 engine, this research was based on an experiment. The investigation was conducted with the use of the diagnostic complex MT-10. The free acceleration was carried out in two ways: by abrupt throttle opening; by turning the injectors on and off at threshold levels with the fixed throttle position. It was found that the method of free acceleration significantly influences the output data concerning the crankshaft rotation frequency.