Fuel rail pressure pulsation analysis for detecting injection-related disturbances in internal combustion engines

Abstract

Reliable diagnostics of internal combustion engine fuel systems is complicated by limited access to electronic control unit data and by the low informativeness of standard diagnostic parameters available through conventional onboard systems. In many cases, ECU-derived parameters are filtered, averaged, or partially inaccessible, which reduces their suitability for detecting local injection-related disturbances. Therefore, the use of direct physical signals, in particular fuel pressure pulsations, is a promising direction for improving the diagnostic informativeness of fuel system monitoring. Goal. The purpose of this study is to assess the possibility of using fuel pressure pulsations as a diagnostic indicator of injection-related disturbances in an internal combustion engine fuel system without relying on internal ECU diagnostic variables. Methodology. Experimental investigations were carried out on a gasoline internal combustion engine equipped with a port fuel injection system. Fuel pressure was measured directly in the fuel rail using a strain-gauge pressure sensor. Synchronous acquisition of fuel pressure, injector current, and crankshaft position signals was performed using a high-speed microcontroller-based data acquisition system. The recorded signals were transformed into the crank-angle domain over a complete 0–720° four-stroke engine cycle. A simulated disturbance was introduced by electrically disconnecting one injector, while the current signal of another active injector was used as a timing reference. Results. The obtained results showed that under normal operation, fuel pressure pulsations have a stable cyclic structure associated with injection events. Injector disconnection caused a systematic deformation of the pressure waveform, reduction of pulsation amplitude, increase in mean rail pressure, and disappearance or significant attenuation of one characteristic pressure minimum within the expected angular sector. Originality. The originality of the study lies in the use of cycle-synchronous fuel pressure pulsation analysis for detecting injection-related disturbances independently of ECU data. Practical value. The proposed approach can serve as a basis for non-intrusive diagnostic and condition monitoring systems for internal combustion engine fuel systems.