A spark ignition type engine enabling engine startability to be favorable is provided. The spark ignition type engine includes a main intake-air passage; a throttle valve of the main intake-air passage; a bypass intake-air passage bypassing the throttle valve; an ISC valve of the bypass intake-air passage; and an electronic control device that controls an engine speed by adjusting an opening degree of the ISC valve, in which when the engine is started, cranking is performed at a cranking opening degree at which the ISC valve is narrowed by a predetermined amount from a fully opened state by control of the electronic control device, so that an intake-air negative pressure is generated on an intake-air downstream side of the ISC valve.

Methods and systems are provided for controlling a boosted engine system, having a turbocharger and a charge air cooler, to limit overheating of a compressor outlet. In one example, a method includes predicting an engine torque profile based on current and future engine operating conditions. The method then models a compressor outlet temperature profile and reduces engine torque output to limit overheating of the compressor outlet.

A spark ignition type engine enabling engine startability to be favorable is provided. The spark ignition type engine includes a main intake-air passage; a throttle valve of the main intake-air passage; a bypass intake-air passage bypassing the throttle valve; an ISC valve of the bypass intake-air passage; and an electronic control device that controls an engine speed by adjusting an opening degree of the ISC valve, in which when the engine is started, cranking is performed at a cranking opening degree at which the ISC valve is narrowed by a predetermined amount from a fully opened state by control of the electronic control device, so that an intake-air negative pressure is generated on an intake-air downstream side of the ISC valve.

An engine control apparatus includes a throttle valve, an accelerator opening detector, a throttle opening controller, and an intake air density detector. The throttle valve is configured to regulate an intake air volume of an engine. The accelerator opening detector is configured to detect an accelerator opening that is an operation amount of an accelerator operation member with which a driver operates an accelerator. The throttle opening controller is configured to increase a throttle opening of the throttle valve in accordance with an increase in the accelerator opening. The intake air density detector is configured to detect information about an intake air density of the engine. In a low intake air density state where the intake air density is a predetermined value or lower, the throttle opening controller decreases a sensitivity of the throttle opening relative to the accelerator opening in a partial range of a range where the accelerator opening is variable.

An engine control apparatus includes a throttle valve, an accelerator opening detector, a throttle opening controller, and an intake air density detector. The throttle valve is configured to regulate an intake air volume of an engine. The accelerator opening detector is configured to detect an accelerator opening that is an operation amount of an accelerator operation member with which a driver operates an accelerator. The throttle opening controller is configured to increase a throttle opening of the throttle valve in accordance with an increase in the accelerator opening. The intake air density detector is configured to detect information about an intake air density of the engine. In a low intake air density state where the intake air density is a predetermined value or lower, the throttle opening controller decreases a sensitivity of the throttle opening relative to the accelerator opening in a partial range of a range where the accelerator opening is variable.

A method for diagnosing a waste gate valve malfunction in a power generation system is presented. The method includes determining an actual pressure differential across a throttle valve. The method further includes determining an estimated pressure differential across the throttle valve based on one or more first operating parameters of the power generation system. Furthermore, the method includes determining an absolute difference between the actual pressure differential and the estimated pressure differential. Moreover, the method also includes comparing the absolute difference with a threshold value and if the absolute difference is greater than the threshold value, determining an operating condition of the throttle valve. Additionally, the method includes determining whether the waste gate valve has malfunctioned based on the determined operating condition of the throttle valve. An engine controller and a power generation system employing the method are also presented.

When atmospheric pressure (Pa) which varies according to altitude is higher than a predetermined pressure threshold (Path) during idle operation in which catalyst warm-up request is issued, an intake pressure is controlled, through a throttle valve (19), to an intake pressure at which an intake air amount required to promote the warm-up of a catalyst converter (26) is obtained. When the atmospheric pressure (Pa) is lower than the predetermined pressure threshold (Path), the intake pressure is controlled, through a throttle valve (19), to an intake pressure (PaPb) at which a differential pressure (Pb) required by a brake booster (8) is obtained. Accordingly, negative pressure in the brake booster (8) can be secured while promoting the warm-up of the catalyst during the idle operation.

Methods and systems are provided for controlling a boosted engine system, having a turbocharger and a charge air cooler, to limit overheating of a compressor outlet. In one example, a method includes predicting an engine torque profile based on current and future engine operating conditions. The method then models a compressor outlet temperature profile and reduces engine torque output to limit overheating of the compressor outlet.

When atmospheric pressure (Pa) which varies according to altitude is higher than a predetermined pressure threshold (Path) during idle operation in which catalyst warm-up request is issued, an intake pressure is controlled, through a throttle valve (19), to an intake pressure at which an intake air amount required to promote the warm-up of a catalyst converter (26) is obtained. When the atmospheric pressure (Pa) is lower than the predetermined pressure threshold (Path), the intake pressure is controlled, through a throttle valve (19), to an intake pressure (PaPb) at which a differential pressure (Pb) required by a brake booster (8) is obtained. Accordingly, negative pressure in the brake booster (8) can be secured while promoting the warm-up of the catalyst during the idle operation.

A method for diagnosing a waste gate valve malfunction in a power generation system is presented. The method includes determining an actual pressure differential across a throttle valve. The method further includes determining an estimated pressure differential across the throttle valve based on one or more first operating parameters of the power generation system. Furthermore, the method includes determining an absolute difference between the actual pressure differential and the estimated pressure differential. Moreover, the method also includes comparing the absolute difference with a threshold value and if the absolute difference is greater than the threshold value, determining an operating condition of the throttle valve. Additionally, the method includes determining whether the waste gate valve has malfunctioned based on the determined operating condition of the throttle valve. An engine controller and a power generation system employing the method are also presented.