Idle speed control for lean burn engine with variable-displacement-like characteristic

A method for controlling an engine having a vehicle having first and second groups of combustion chambers, comprising:

• determining whether the vehicle is an idle speed control condition;
• determining a desired engine output based on a driver actuated element;
• when operating in said idle speed control condition:
• inducting air and injecting fuel into the first group of combustion chambers, inducting air and injecting substantially no fuel into the second group of combustion chambers, and adjusting said injected fuel to the first combustion chamber group based on a desired speed and a determined speed;
• and;
• when operating in a preselected condition other than said idle speed control condition:
• adjusting at least one of fuel injected or air inducted to both cylinder groups based on said desired engine output.

A method for controlling an engine having a first and second group of combustion chambers, comprising:

• inducting air and injecting fuel into the first combustion chamber group at a first average air-fuel ratio;
• inducting air and not injecting fuel into the second combustion chamber group;
• adjusting said injected fuel to the first combustion chamber group based on a desired speed and a determined speed;
• and
• treating a mixture of exhaust gasses from said first and second combustion chamber group in an emission control device.

A method for controlling an engine having a first and second group of combustion chambers, comprising:

• inducting air and injecting fuel into the first combustion chamber group at a first average air-fuel ratio;
• inducting air and not injecting fuel into the second combustion chamber group;
• and
• adjusting said injected fuel to the first combustion chamber group based on a desired engine idle speed and a determined engine idle speed during idle speed control conditions.

A method for controlling an engine having a first and second group of combustion chambers, comprising:

• inducting air and injecting fuel into the first combustion chamber group at a first average air-fuel ratio;
• inducting air and not injecting fuel into the second combustion chamber group;
• adjusting said injected fuel to the first combustion chamber group based on a desired speed and a determined speed;
• and
• transitioning to operation with injected fuel in said second group when manifold vacuum falls below a predetermined value.