Abstract: An inter-cylinder air/fuel ratio imbalance abnormality detection apparatus for a multicylinder internal combustion engine includes a fuel injection amount change control portion that executes a fuel injection amount change control of forcing a fuel injection amount of a predetermined object cylinder to change by a predetermined amount; an ignition timing retardation control portion that executes an ignition timing retardation control for the predetermined object cylinder; and a detection portion that detects an inter-cylinder air/fuel ratio imbalance abnormality based on output fluctuation regarding the predetermined object cylinder occurring when the fuel injection amount change control and the ignition timing retardation control are executed together for the predetermined object cylinder.

Abstract: An engine ECU executes a program including the steps of: starting an engine by transiently increasing an amount of fuel injection when a start request is detected; prohibiting calculation of a learn value when a condition for stopping transient increase is not satisfied; stopping transient increase when the condition for stopping transient increase is satisfied; steadily increasing the amount of fuel injection in accordance with a coolant temperature TW; and permitting calculation of a learn value during steady increase in accordance with the coolant temperature TW.

Abstract: A drive control circuit supplies power to a solenoid coil in an in-cylinder injector of a cylinder in response to a fuel injection signal. A failure detection circuit to detect disconnection failure at an in-cylinder injector is arranged to be shared among cylinders whose phase of each stroke differs 360 degrees in crank angle. An engine ECU detects failure including identification of the injector with disconnection failure based on a failure detection signal from the failure detection circuit, and a crank angle detected by a crank angle sensor. The driver is notified of the failure detection result through the engine ECU.

Abstract: At the time of startup of an engine having an in-cylinder injector and an intake manifold injector, a risk of pre-ignition during the first-time compression stroke is determined based on a rotational angle of a crankshaft at the time of previous engine stop. When there is a high risk of pre-ignition, fuel injection from the in-cylinder injector having been set to make an air-fuel ratio within the combustion chamber become out of a range enabling combustion (to attain an over-rich condition) is carried out in addition to fuel injection from the intake manifold injector for normal engine startup. Pre-ignition is thus prevented, and smooth engine startup is ensured.

Abstract: When an injection sharing ratio r is neither 0 nor 1, an engine ECU executes a program including a step of calculating a purge reduction amount of an in-cylinder injector as fpg×r and calculating a purge reduction amount of an intake manifold injector as fpg×(1?r) when performing purge processing according to a current fuel injection sharing ratio of the injectors, and a step of calculating a correction fuel injection amount of the in-cylinder injector by raising the fuel injection amount to a minimum fuel injection amount, and calculating a correction fuel injection amount of the intake manifold injector by subtracting the raised amount from the fuel injection amount of the intake manifold injector when the fuel injection amount of the in-cylinder injector calculated by using the purge reduction amount is lower than the minimum injection amount.

Abstract: In an internal combustion engine where an in-cylinder injector and an intake manifold injector can both be used, initial setting of a fuel injection ratio (DI ratio) in accordance with a condition of the engine is basically carried out in response to power-up of an engine ECU. Further, it is sensed that an engine start request is made after a prescribed period has elapsed since the power-up. In such a case, an initial setting value of the fuel injection ratio is updated in accordance with the condition of the engine at that time point. Thus, the fuel injection ratio between both injectors can appropriately be set in starting the engine, so that the engine is smoothly started.

Abstract: For an internal combustion engine having an in-cylinder injector and an intake manifold injector, setting of the ratio of fuel injection (DI ratio) between these injectors is changed depending on whether the intake manifold injector is in a high temperature state or a non-high temperature state (normal state). Specifically, when the intake manifold injector is at a high temperature, the setting of the DI ratio is controlled so that the quantity of fuel to be injected from the intake manifold injector is larger than that according to setting of the fuel injection quantity in the normal state under the same engine conditions.

Abstract: An engine ECU executes a program including the steps of: when the port fuel injection ratio is 100% (YES at S200), sensing the engine coolant temperature THW (S210); when the engine coolant temperature THW is higher than a threshold value (YES at S220), monitoring fuel pressure P in a high-pressure delivery pipe (S230); and when fuel pressure P rises by the received heat (YES at S240), identifying that there is no error at the high-pressure fuel system.

Abstract: An engine ECU executes a program including the steps of: detecting an air-fuel ratio; calculating a learn value of a feedback correction amount for total fuel injection amount calculated based on the air-fuel ratio, for a plurality of learning regions obtained as a result of division corresponding to an intake air amount; interpolating the learn value at an intake air amount different from the intake air amount detected at the time of calculation of the learn value, based on the calculated learn value; and correcting an amount of fuel injection based on the obtained learn value.

Abstract: Avoiding inconvenience during purge processing execution of fuel vapor in an internal combustion engine including an in-cylinder injector and an intake manifold injector. An engine ECU 300 executes a program including the steps of: when the purge control execution flag is ON (YES at S400), the step (S410) of calculating injection ratio (DI ratio) r; the step (420) of calculating the basic injection amounts of the in-cylinder injector and the intake manifold injector; when the injection ratio r is not 0 (NO at S430) and the injection ratio r is not 1 (NO at S460), the step (S480) of substituting 0 for purge reduction calculation value fpgd at the in-cylinder injector side, and substituting fpg for purge reduction calculation value fpgp of the intake manifold injector side; and the step (490) of calculating the final injection amounts of the in-cylinder injector and the intake manifold injector.

Abstract: When an injection sharing ratio r is neither 0 nor 1, an engine ECU executes a program including a step of calculating a purge reduction amount of an in-cylinder injector as fpg×r and calculating a purge reduction amount of an intake manifold injector as fpg×(1-r) when performing purge processing according to a current fuel injection sharing ratio of the injectors, and a step of calculating a correction fuel injection amount of the in-cylinder injector by raising the fuel injection amount to a minimum fuel injection amount, and calculating a correction fuel injection amount of the intake manifold injector by subtracting the raised amount from the fuel injection amount of the intake manifold injector when the fuel injection amount of the in-cylinder injector calculated by using the purge reduction amount is lower than the minimum injection amount.

Abstract: An engine ECU executes a program including the steps of calculating an in-cylinder injector's injection ratio; if the ratio is 1, calculating an amount of cold state spark advance by employing a function f(1) having the engine's temperature as a parameter; if the ratio is 0, calculating an amount of cold state spark advance by employing a function f(2) having the engine's temperature as a parameter; and if the ratio is larger than 0 and smaller than 1, calculating an amount of cold state spark advance by employing a function f(3) having the engine's temperature and the ratio as parameters.

Abstract: An engine ECU executes a program including the steps of: when the port fuel injection ratio is 100% (YES at S200), sensing the engine coolant temperature THW (S210); when the engine coolant temperature THW is higher than a threshold value (YES at S220), monitoring fuel pressure P in a high-pressure delivery pipe (S230); and when fuel pressure P rises by the received heat (YES at S240), identifying that there is no error at the high-pressure fuel system.

Abstract: For an internal combustion engine having an in-cylinder injector and an intake manifold injector, setting of the ratio of fuel injection (DI ratio) between these injectors is changed depending on whether the intake manifold injector is in a high temperature state or a non-high temperature state (normal state). Specifically, when the intake manifold injector is at a high temperature, the setting of the DI ratio is controlled so that the quantity of fuel to be injected from the intake manifold injector is larger than that according to setting of the fuel injection quantity in the normal state under the same engine conditions.

Abstract: A high pressure fuel pump boosts the pressure of fuel to discharge a quantity according to the closing period of an electromagnetic spill valve. A fuel distributor pipe receives and delivers to an in-cylinder injector the fuel discharged from the high pressure fuel pump. A fuel pressure sensor measures a fuel pressure Pt in a fuel distributor pipe. The control of open/closure of the electromagnetic spill valve according to the insufficient fuel pressure with respect to the target pressure of fuel pressure Pt is carried out in a manner similar to that of in-cylinder injection execution even during an in-cylinder injection suppressing period in which fuel is not injected from the in-cylinder injector. Accordingly, fuel pressure can be controlled at high accuracy during the in-cylinder injection suppressing period and subsequent in-cylinder injection resuming time.

Abstract: An engine ECU executes a program comprising the steps of: calculating a post-warm-up steady-state port wall deposit quantity (a); calculating a shared-injection steady-state port wall deposit quantity (b) based on port wall deposit quantity (a); calculating a difference (c) in one cycle of shared-injection steady-state port wall deposit quantity (b); making a correction considering an engine temperature and an engine speed to calculate a transition correction quantity (d); and converting transition correction quantity (d) into a wave form representing temporal transition to make a wall deposit correction with higher priority on a port injection quantity.

Abstract: An engine ECU executes a program including the steps of: starting an engine by transiently increasing an amount of fuel injection when a start request is detected; prohibiting calculation of a learn value when a condition for stopping transient increase is not satisfied; stopping transient increase when the condition for stopping transient increase is satisfied; steadily increasing the amount of fuel injection in accordance with a coolant temperature TW; and permitting calculation of a learn value during steady increase in accordance with the coolant temperature TW.

Abstract: In an internal combustion engine where an in-cylinder injector and an intake manifold injector can both be used, initial setting of a fuel injection ratio (DI ratio) in accordance with a condition of the engine is basically carried out in response to power-up of an engine ECU. Further, it is sensed that an engine start request is made after a prescribed period has elapsed since the power-up. In such a case, an initial setting value of the fuel injection ratio is updated in accordance with the condition of the engine at that time point. Thus, the fuel injection ratio between both injectors can appropriately be set in starting the engine, so that the engine is smoothly started.

Abstract: At the time of startup of an engine having an in-cylinder injector and an intake manifold injector, a risk of pre-ignition during the first-time compression stroke is determined based on a rotational angle of a crankshaft at the time of previous engine stop. When there is a high risk of pre-ignition, fuel injection from the in-cylinder injector having been set to make an air-fuel ratio within the combustion chamber become out of a range enabling combustion (to attain an over-rich condition) is carried out in addition to fuel injection from the intake manifold injector for normal engine startup. Pre-ignition is thus prevented, and smooth engine startup is ensured.

Abstract: A drive control circuit supplies power to a solenoid coil in an in-cylinder injector of a cylinder in response to a fuel injection signal. A failure detection circuit to detect disconnection failure at an in-cylinder injector is arranged to be shared among cylinders whose phase of each stroke differs 360 degrees in crank angle. An engine ECU detects failure including identification of the injector with disconnection failure based on a failure detection signal from the failure detection circuit, and a crank angle detected by a crank angle sensor. The driver is notified of the failure detection result through the engine ECU.