Abstract: A diagnostic system for a discrete variable valve lift system of an internal combustion engine is provided. The system includes: a Fast Fourier Transform (FFT) module that generates a frequency content signal based on a FFT method and a valve impact sensor signal; and a malfunction module that selectively diagnoses a malfunction of a discrete variable valve lift system based on the frequency content signal.

Abstract: A diagnostic system for a discrete variable valve lift system of an internal combustion engine is provided. The system includes: a Fast Fourier Transform (FFT) module that generates a frequency content signal based on a FFT method and a valve impact sensor signal; and a malfunction module that selectively diagnoses a malfunction of a discrete variable valve lift system based on the frequency content signal.

Abstract: A diagnostic control system for an internal combustion engine including a discrete variable valve lift (DVVL) system includes a first module that determines a knock threshold value based on engine operating parameters and an engine knock sensor that generates a knock signal. A second module monitors a portion of the knock signal that is associated with a particular cylinder of the engine, selectively identifies a fault of at least one valve of the DVVL system associated with the particular cylinder based on the portion and the knock threshold, and outputs a fault signal corresponding to the particular cylinder.

Abstract: A system and method are provided for determining an ethanol content of a fuel that is part of a fuel and air mixture combusted within an internal combustion engine. A pressure characteristic of a fuel rail is monitored during operation of the engine. At least one of an effective bulk modulus of the fuel and a pressure perturbation signature is determined based on the pressure characteristic. The ethanol content is determined based on the at least one of the effective bulk modulus and the pressure perturbation signature.

Abstract: A fuel injection system for a direct fuel injection (DFI) engine is provided. The system includes: injection mode module selects a fuel injection mode to be one of a single injection mode and a dual injection mode during DFI engine idle operation based on a torque request; and a fuel injection command module that commands fuel injection events based on a crankshaft position and the fuel injection mode.