An engine control system includes: a target air mass module configured to determine a target mass of air within a cylinder of an engine based on a torque request; a boost control module configured to control boost provided by a turbocharger based on the torque request; an exhaust gas recirculation (EGR) control module configured to selectively: set a target opening of an EGR valve based on the target mass of air; set the target opening of the EGR valve to a predetermined minimum opening, where the predetermined minimum opening is greater than zero percent open; and control opening of the EGR valve based on the target opening of the EGR valve.

An Exhaust Gas Recirculation (EGR) effective flow diagnosis method includes: measuring an EGR gas temperature by an EGR gas temperature sensor under an EGR gas temperature rise condition of an EGR system on an intake line; determining the degree of the EGR gas temperature rise; and determining whether an EGR effective flow is excessive or insufficient according to the degree of the EGR gas temperature rise.

Methods and systems are provided for adjusting an EGR valve operation based on results from an EGR valve diagnostic. In one example, a method may include executing the EGR valve diagnostic during an engine deactivation, wherein the EGR valve diagnostic estimates an EGR valve stickiness used to adjust the EGR valve operation.

Methods and systems are provided for diagnosing degradation of an exhaust gas recirculation (EGR) valve. In one example, a method may include, during a vehicle key-off condition, routing compressed air through an EGR passage housing the EGR valve, and indicating degradation of the EGR valve based on a change in an estimated EGR pressure, upon a commanded change in EGR valve position.

Methods and systems are provided for diagnosing degradation of an exhaust gas recirculation (EGR) valve. In one example, a method may include, during a vehicle key-off condition, routing compressed air through an EGR passage housing the EGR valve, and indicating degradation of the EGR valve based on a change in an estimated EGR pressure, upon a commanded change in EGR valve position.

An engine system includes an injector, an EGR device (including an EGR valve having a step motor) to recirculate part of exhaust gas of an engine as EGR gas to the engine, and an electronic control unit (ECU) to control the injector, the EGR valve, and others based on an operating state of the engine. The ECU is configured to diagnose foreign-matter lodging abnormality of the EGR valve and a lodged foreign-matter diameter based on detected intake pressure during engine deceleration. When existence of the abnormality and the foreign-matter diameter are determined, the ECU controls the step motor to hold the EGR valve at a first opening degree smaller than a second opening degree needed to remove a foreign matter before fuel cut to the engine by the injector.

A position sensor malfunction determination apparatus includes a determination unit and a controller. The determination unit is configured to perform a determination relating to electricity supply failure in a position sensor. The controller is configured to perform a fail-safe control. The determination unit is configured to determine whether each of conditions (A) and (B) is established, in a preliminarily determination before occurrence of the electricity supply failure in the position sensor is finally determined. The determination unit is configured to determine that the position sensor has a probability of the electricity supply failure when both the conditions (A) and (B) are determined to be established in the preliminarily determination. The controller is configured to execute, when the determination unit determines that the position sensor has the probability of the electricity supply failure, the fail-safe control before the occurrence of the electricity supply failure in the position sensor is finally determined.

A position sensor malfunction determination apparatus includes a determination unit and a controller. The determination unit is configured to perform a determination relating to electricity supply failure in a position sensor. The controller is configured to perform a fail-safe control. The determination unit is configured to determine whether each of conditions (A) and (B) is established, in a preliminarily determination before occurrence of the electricity supply failure in the position sensor is finally determined. The determination unit is configured to determine that the position sensor has a probability of the electricity supply failure when both the conditions (A) and (B) are determined to be established in the preliminarily determination. The controller is configured to execute, when the determination unit determines that the position sensor has the probability of the electricity supply failure, the fail-safe control before the occurrence of the electricity supply failure in the position sensor is finally determined.

This engine system is provided with: an engine; an intake passage; an exhaust passage; an electronic throttle device; an EGR device including an EGR valve; a fresh-air flow device including a fresh-air inflow valve; and an ECU. The ECU, in order to throttle intake air to the engine during deceleration of the engine, causes the electronic throttle device to be closed from an open valve state to a predetermined deceleration opening while causing the EGR valve to become closed to shut off introduction of EGR gas into the intake passage, and, in order to introduce fresh air into the intake passage (intake manifold) downstream of the electronic throttle device, causes the fresh-air inflow valve to become opened from the closed valve state at a timing delayed by a predetermined period from the timing of closing the electronic throttle device.

An EGR malfunction detection system includes an EGR valve configured to open and close an exhaust recirculation path for recirculating an exhaust gas from an exhaust channel to an intake channel of an engine, a measurement unit configured to measure an intake pressure inside the intake channel, a valve controller configured to control the EGR valve, and a malfunction detector configured to detect an anomaly in the exhaust recirculation path in accordance with a measurement unit output and a valve controller output. The malfunction detector determines whether the EGR valve is stuck in accordance with the intake pressures measured when the EGR valve is controlled to open and close. If the EGR valve is stuck, the malfunction detector determines whether the EGR valve is stuck in an open state, stuck in a closed state, or stuck in an intermediate state by comparing the measured pressure with predetermined thresholds.