Abstract: An electronic control unit for an internal combustion engine that includes an engine-driven alternator diagnoses on the bases of an air-fuel ratio correction amount in air-fuel ratio feedback control whether a rich abnormality that the air-fuel ratio of air-fuel mixture is excessively rich is occurring in a fuel injection system. When the state of charge of a battery charged with electric power generated by the alternator is higher than or equal to a predetermined value, charging control for setting a voltage generated by the alternator at a voltage lower than a normal generated voltage is executed. When the state of charge of the battery is higher than or equal to the predetermined value, charging control for charging the battery at the voltage is prohibited when a degree of mixing of fuel in lubricating oil of the internal combustion engine is higher than or equal to a predetermined degree.

Abstract: In a direct injection internal combustion engine which switches a fuel injection mode between a batch injection in which fuel is injected once and a split injection in which fuel is injected at a plurality of timings, a fuel increase amount is set larger for the split injection than for the batch injection when increase-correcting a fuel injection quantity set based on an engine operating state.

Abstract: If two-split injection logic has been adopted, an engine ECU executes a program including the steps of calculating first injection start timing of the two-split injection logic, calculating second injection start timing of the two-split injection logic, calculating a first injection permitted time period A of the two-split injection logic, calculating a first injection required time period B of the two-split injection logic, and adopting single injection logic instead of the two-split injection logic if the first injection start timing A of the two-split injection logic is shorter than the first injection required time period B of the two-split injection logic.

Abstract: A controller for a direct-injection internal combustion engine in which fuel is directly injected into a combustion chamber via a fuel injection valve, and a mixture formed thereby is burned by igniting the mixture via an ignition plug, which the controller, when the internal combustion engine is started under very low temperature conditions, controls an ignition cut operation that inhibits ignition and performs fuel injection only, the controller including an engine-start control unit that, when the internal combustion engine is started under very low temperature conditions after the ignition cut operation was performed, determines whether there is fuel that can contribute to combustion in a cylinder and if there is, inhibits the ignition cut operation, or limits a number of times of the cutting off of ignition.

Abstract: In a direct injection internal combustion engine (10) which switches a fuel injection mode between a batch injection in which fuel is injected once and a split injection in which fuel is injected at a plurality of timings, a fuel increase amount is set larger for the split injection than for the batch injection when increase-correcting a fuel injection quantity set based on an engine operating state.

Abstract: A requested injection amount of fuel necessary during ignition cut-off at the time of start at an extremely low temperature is calculated (step ST2), injection start timing and injection end timing between which wetting of a spark plug by fuel is less likely are set (step ST3), and the number of times of ignition cut-off is calculated based on the injection start timing and the injection end timing and the requested injection amount (step ST4). The injection start timing and the injection end timing are thus restricted to timings between which plug wetting is less likely, and the number of times of ignition cut-off is calculated based on the injection start timing and the injection end timing and the requested injection amount, so that wetting of the spark plug by fuel at the extremely low temperature can be avoided even in an in-cylinder direct-injection engine.

Abstract: After initial combustion at the time of engine startup under very low temperature conditions, a fuel-injection start time point and a fuel-injection end time point are restricted to a period of time during which smoldering of an ignition plug is less prone to occur, to warm up the inside of a cylinder and increase engine speed. Thereafter, a fuel injection period is adjusted by gradually elongating it by reducing the restriction on the injection start time point and the injection end time point each time the engine speed exceeds a predetermined value in the course of the increase in the engine speed. In this way, the engines are made to reach a state where the engine can operate in a self-sustaining manner, before smoldering of the ignition plugs progresses after the initial combustion at the time of the engine startup under very low temperature conditions.

Abstract: It is determined whether there is a fuel-injection history when the engine is started under very low temperature conditions. If there is the fuel-injection history, a current number of times cutting off ignition is to be performed is calculated, using a requested number of times of cutting off of ignition, and a recorded number of times of fuel injection in the fuel-injection history during cutting off ignition that was performed when it was attempted to start the engine last time. Cutting off ignition is performed based on the calculated value.

Abstract: After initial combustion at the time if engine startup under very low temperature conditions, a fuel-injection start time point and a fuel-injection end time point are restricted to a period of time during which smoldering of an ignition plug is less prone to occur, to warm up the inside of a cylinder and increase engine speed. Thereafter, a fuel injection period is adjusted by gradually elongating it by reducing the restriction on the injection start time point and the injection end time point each time the engine speed exceeds a predetermined value in the course of the increase in the engine speed. In this way, the engines are made to reach a state where the engine can operate in a self-sustaining manner, before smoldering of the ignition plugs progresses after the initial combustion at the time of the engine startup under very low temperature conditions.

Abstract: A requested injection amount of fuel necessary during ignition cut-off at the time of start at an extremely low temperature is calculated (step ST2), injection start timing and injection end timing between which wetting of a spark plug by fuel is less likely are set (step ST3), and the number of times of ignition cut-off is calculated based on the injection start timing and the injection end timing and the requested injection amount (step ST4). The injection start timing and the injection end timing are thus restricted to timings between which plug wetting is less likely, and the number of times of ignition cut-off is calculated based on the injection start timing and the injection end timing and the requested injection amount, so that wetting of the spark plug by fuel at the extremely low temperature can be avoided even in an in-cylinder direct-injection engine.

Abstract: In response to start of cranking in an internal combustion engine by a starter, a fuel injection control starts. When an initial combustion of the fuel injected into the internal combustion engine is detected based on a rotational speed of a crankshaft, it is determined that the internal combustion engine in a warm-up period, and a control for reducing a fuel injection period is executed. When it is detected that the rotational speed of the crankshaft exceeds a predetermined rotational speed, it is determined that the internal combustion engine is in a start-up promotion period, and a control for extending the fuel injection period is executed.

Abstract: In response to start of cranking in an internal combustion engine by a starter, a fuel injection control starts. When an initial combustion of the fuel injected into the internal combustion engine is detected based on a rotational speed of a crankshaft, it is determined that the internal combustion engine in a warm-up period, and a control for reducing a fuel injection period is executed. When it is detected that the rotational speed of the crankshaft exceeds a predetermined rotational speed, it is determined that the internal combustion engine is in a start-up promotion period, and a control for extending the fuel injection period is executed.

Abstract: A fuel vapor treating mechanism includes a canister for adsorbing fuel vapor produced in a fuel feed system. The treating mechanism purges the fuel vapor adsorbed by the canister, along with air, to an intake system of the engine. An ECU computes a value representing the flow rate of the purged gas as a value that represents the capability of the treating apparatus. The ECU sets a decision value in accordance with the amount of the fuel vapor produced in the fuel feed system. The decision value represents a required capability of the treating mechanism. When the value representing the capability is less than the decision value, the ECU prohibits stratified charge combustion and causes the engine to perform homogeneous charge combustion. Therefore, as many opportunities as possible are provided to perform stratified charge combustion, which improves fuel efficiency.