A method and system for estimating air mass per cylinder of an internal combustion engine is provided. An output signal from a MAF sensor is digitally processed to provide an estimate air mass per cylinder (APC). The system includes the MAF sensor; a data acquisition unit configured to receive an output signal from the MAF sensor and produce a sampled signal having a sampling rate greater than one sample per firing event; a multiple band pass (MBP) filter configured to remove signal components caused by airflow pulsations and oscillations through the MAF sensor; an envelope detector configured to detect the lower and upper envelopes of the MBP filtered signal; a MAF estimator configured to estimate a mass airflow based on the detected lower and upper envelopes; a signal decimator; a low pass filter; and a APC converter to converted the low pass filtered signal into an estimated APC.

In some examples, a system includes an airflow sensor disposed at least partially within an air intake system for an engine. The airflow sensor may be configured to measure a flow rate of air flowing past the airflow sensor in the air intake system, and includes a sensor element and a heater associated with the sensor element. A heater control circuit may control the heater to control a temperature of the sensor element. Further, a processor may be configured by executable instructions to cause the heater control circuit to, in a first operation mode, maintain the sensor element at a higher temperature range, and, in a second operation mode, maintain the sensor element at a lower temperature range that is above an ambient temperature and that is lower than the higher temperature range.

An object is to provide a control device that calculates an intake pipe pressure of an engine, in which the humidity of air is measured, and a change in a gas constant due to a change in the total number of moles of air is corrected, to improve the accuracy of the calculation value of the intake pipe pressure. A control device that controls an engine provided with an air amount measurement unit that measures an air amount passing through a throttle throttle valve provided in an intake passage of the engine, and a humidity measurement unit that measures a humidity of air passing through the throttle throttle valve, includes: an air amount calculation unit that calculates an air amount flowing into a cylinder of the engine based on a measurement result of the air amount measurement unit; and a pressure calculation unit that calculates a pressure of the intake manifold on a downstream side of the throttle throttle valve based on the air amount measured by the air amount measurement unit, the air amount calculated by the air amount calculation unit, and the humidity measured by the humidity measurement unit.

A method of two-step variable valve lift (VVL) malfunction avoidance learning control may include: in a two-step VVL system which is operated with a main lift and a secondary lift, verifying, by an electronic control unit (ECU), an operation avoidance area based on locking of a lock pin of a cam follower ; performing VVL operation learning, in which a failure of occurrence of the second lift is determined on the basis of a locking failure of the cam follower due to an initially set value of the operation avoidance area; and reflecting the operation avoidance area to the two-step VVL system with a corrected set value which is obtained through the VVL operation learning.

An intake air amount measuring device includes a by-pass-type air flowmeter and a processor that calculates an intake air amount of an engine based on the measurement result of the air flowmeter. When calculating the intake air amount, the processor performs lag or lead compensation for a response delay of a change in an intake flow rate in the bypass passage in relation to a change in an intake flow rate in the main passage based on loss coefficients of the main passage and the bypass passage. The processor causes values of the loss coefficients of the main passage and the bypass passage, which are used in the compensation, to be different between a forward flow state, in which the intake air flows through the main passage in a forward direction, and a back-flow state, in which the intake air flows through the main passage in a reverse direction.

Provided is a vehicle-mounted system capable of transmitting a command to a first system from a second system during a period in which the first system communicates with the second system according to a unidirectional communication protocol. A vehicle-mounted system 100 includes a sensor 10 (first system) and an ECU (second system). The sensor 10 outputs a message signal including a pause pulse to the communication line DATA according to SENT (a unidirectional communication protocol). The ECU 20 is connected to the communication line DATA, and transmits a command to the sensor 10 using the falling period of the pause pulse.

A flow rate detector includes a detection circuit, which is configured to output as an analog signal a voltage in accordance with a flow rate of air flowing through an intake pipe, and a conversion circuit, which is configured to convert the analog signal input from the detection circuit to a digital signal based on an analog-to-digital conversion characteristic to output the digital signal. The analog signal that corresponds to a forward flow direction and is input to the conversion circuit is set to have a value larger than an input voltage range in which a missing code may occur in the analog-to-digital conversion characteristic.

With respect to a vehicle mass air-flow sensor that includes a temperature sensor for measuring a temperature of a sensor element of the mass air-flow sensor, a method for controlling a heating element for heating the sensor element of a mass air-flow sensor includes identifying a dew formation on the sensor element by evaluating a temperature profile that is recorded during an operation of the vehicle using the temperature sensor, and generating a switch-on signal for switching on the heating element in response to the identification of the dew formation.

An air-fuel ratio control method reflecting a brake booster inflow flow rate includes: determining a deviation between an actually measured pressure of an intake manifold and a model pressure of the intake manifold is equal to or greater than a predetermined value; determining that the deviation is caused by a brake operation; correcting an intake air amount by reflecting a flow rate flowing into the intake manifold from a brake booster; and performing an air-fuel ratio control based on the corrected intake air amount.

This signal processing unit includes: a comparison signal output unit which outputs a comparison signal on a negative side that corresponds to a negative side portion, of a second amplitude-increased signal, which is on the negative side with respect to the comparison threshold TH; an averaging processing unit which outputs an average signal obtained by averaging the comparison signal; a coefficient multiplication processing unit which outputs a coefficient-multiplied signal obtained by multiplying the average signal by an adjustment coefficient set in advance; and a signal correction processing unit which outputs, as a flow rate signal, a value obtained by correcting a first amplitude-increased signal so as to be decreased by use of the coefficient-multiplied signal, wherein the comparison threshold TH is set on the basis of an output characteristic of a sensor measured in advance with respect to at least a forward flow direction of an intake air.