Patent ID: 7533563

Claim:
A method of monitoring at least one fuel injector of an engine to determine whether the fuel injector is operating properly, said method including the steps of: (a) providing a stress wave sensor for detecting stress transients corresponding to at least one of (i) intensity of an impact of a portion of a fuel injector pintle striking a first portion of a fuel injector body upon opening of said at least one fuel injector, and (ii) intensity of an impact of a portion of the fuel injector pintle striking a second portion of the fuel injector body upon closing of said at least one fuel injector; (b) measuring stress wave signal corresponding to at least one of (i) intensity of an impact of a portion of the fuel injector pintle striking a first portion of a fuel injector body upon opening of said at least one fuel injector, and (ii) intensity of an impact of a portion of the fuel injector pintle striking a second portion of the fuel injector body upon closing of said at least one fuel injector; and, (c) evaluating stress wave signal measured in step (b) to determine if said at least one fuel injector is operating properly.