Reduction in turbocharger lag at high altitudes

A method of operating a vehicle's turbocharged engine comprising:

• determining barometric pressures for a given engine speed and load;
• the barometric pressures comprising a first barometric pressure and a second barometric pressure being lower than the first barometric pressure;
• advancing an ignition spark by a first amount relative to top dead center in one of a plurality of cylinders, which undergoes the compression stroke for the given engine speed and load at the first barometric pressure;
• and
• advancing an ignition spark by a second amount relative to top dead center in the one of the plurality of said cylinders, which undergoes the compression stroke for the given engine speed and load at the second barometric pressure;
• the second amount being less than the first amount relative to top dead center in the one of the plurality of said cylinders, which undergoes the compression stroke for the given engine speed and load,
• reducing the first amount of ignition spark advance during a first tip-in at the first barometric pressure, and
• reducing the second amount of ignition spark advance during a second tip-in at the second barometric pressure.

A method of operating a turbocharged engine of a motor vehicle, the engine having cylinders comprising:

• interrogating a motor vehicle operation in responsive to barometric pressures at different altitudes;
• the barometric pressures comprising a first barometric pressure and a second barometric pressure being lower than the first barometric pressure;
• advancing an ignition spark by a first amount relative to top dead center in one of the cylinders, which undergoes the compression stroke for the given engine speed and load at the first barometric pressure while operating the engine at a first idle speed;
• and
• advancing an ignition spark by a second amount relative to top dead center in the one of the cylinders, which undergoes the compression stroke for the given engine speed and load at the second barometric pressure while operating the engine at a second idle speed;
• the second amount being less than the first amount relative to top dead center in the one of the cylinders, which undergoes the compression stroke for the given engine speed and load;
• and
• wherein the second idle speed is higher than the first idle speed of the engine for the given engine speed and load.