Method and apparatus for engine cylinder balancing using sensed engine speed

A method for engine cylinder balancing, comprising the steps of:

• a) sensing a speed of the engine a plurality of times during a time period;
• b) performing a Fourier Transform upon the sensed engine speed, thereby producing at least first, second and third Fourier Transform Components corresponding respectively to 0.5, 1.0 and 1.5 engine orders of the engine;
• c) determining a single cylinder imbalance condition of the engine from a phase of the first Fourier Transform component;
• d) applying a first predetermined adjustment to a fueling command of the engine based upon the determination made at step (c), wherein the first predetermined adjustment is selected to reduce an absolute value of the first Fourier Transform component;
• e) determining bank-to-bank symmetric imbalances of the engine from a phase of the second Fourier Transform component;
• f) applying a second predetermined adjustment to the fueling command of the engine based upon the determination made at step (e), wherein the second predetermined adjustment is selected to reduce an absolute value of the second Fourier Transform component;
• g) determining bank-to-bank offset imbalances of the engine from a phase of the third Fourier Transform component;
• and
• h) applying a third predetermined adjustment to the fueling command of the engine based upon the determination made at step (g), wherein the third predetermined adjustment is selected to reduce an absolute value of the third Fourier Transform component.

A system for engine cylinder balancing, comprising:

• means for sensing a speed of the engine a plurality of times during a time period;
• means for performing a Fourier Transform upon the sensed engine speed, thereby producing at least one Fourier Transform component corresponding to an engine order of the engine;
• means for determining a cylinder imbalance condition from a phase of the Fourier Transform component;
• and
• means for applying a predetermined adjustment to a fueling command of the engine, wherein the predetermined adjustment is selected based upon the determination made by the means for determining.

A system for engine cylinder balancing, comprising:

• means for sensing a speed of the engine a plurality of times during a time period;
• means for performing a Fourier Transform upon the sensed engine speed, thereby producing at least first, second and third Fourier Transform Components corresponding respectively to 0.5, 1.0 and 1.5 engine orders of the engine;
• first means for determining a single cylinder imbalance condition of the engine from a phase of the first Fourier Transform component;
• means for applying a first predetermined adjustment to a fueling command of the engine based upon the determination made by the first means for determining, wherein the first predetermined adjustment is selected to reduce an absolute value of the first Fourier Transform component;
• second means for determining bank-to-bank symmetric imbalances of the engine from a phase of the second Fourier Transform component;
• means for applying a second predetermined adjustment to the fueling command of the engine based upon the determination made by the second means for determining, wherein the second predetermined adjustment is selected to reduce an absolute value of the second Fourier Transform component;
• third means for determining bank-to-bank offset imbalances of the engine from a phase of the third Fourier Transform component;
• and
• means for applying a third predetermined adjustment to the fueling command of the engine based upon the determination made by the third means for determining, wherein the third predetermined adjustment is selected to reduce an absolute value of the third Fourier Transform component.