Patent ID: 6546912
Filing Date: 2003-04-15
Classification: F02D

Abstract:
A method for cylinder balancing of an engine having a plurality of fuel injectors, comprising the steps of:a. sensing a speed of the engine a plurality of times during a time period; b. filtering the sensed engine speed, thereby producing engine speed fluctuation data at predetermined frequencies corresponding to respective ones of the plurality of fuel injectors; c. comparing the filtered engine speed fluctuations to a first predetermined threshold value; d. comparing the engine speed fluctuations to a second predetermined threshold value when the engine speed fluctuations did not satisfy the threshold conditions in step (c); e. if the engine speed fluctuations did not satisfy the threshold conditions in step (d); performing steps e.1 through e.4; e.1 resetting all fuel injector trims to a predetermined value and calculating the total engine speed fluctuation; e.2 for a first one of the plurality of fuel injectors reducing fuel injector fueling by a predetermined value and calculating a new total engine speed fluctuation; e.3 generating a fault code for the first fuel injector when the calculated engine speed fluctuations from steps (e.1) and (e.2) are equal; e.4 repeating steps (e.1) through (e.3) for each remaining fuel injector; f. if the engine speed fluctuations satisfy the threshold conditions in step (d); performing steps f.1 through f.3; f.1 adjusting the trim for the first fuel injector and calculating the total engine speed fluctuation; f.2 readjusting the trim for the first fuel injector until the calculated total engine speed fluctuation is at a local minimum; f.3. repeating steps (f.1) through (f.2) for all fuel injectors; and g. generating fault codes corresponding to adjustments made to each of the fuel injectors.