Abstract: A control module and method for operating the same includes a diurnal control valve module that opens a diurnal control valve (DCV) and an evaporative leak check module (ELCM) diverter valve control module that switches on an ELCM diverter valve. The control module includes a correlation module performs a correlation of a ELCM pressure signal and a fuel tank pressure signal and that generates a fault signal in response to the correlation when the DCV valve is open and the ELCM diverter valve is on.

Abstract: A control system includes a switching valve control module, a pressure determination module, and a fuel system diagnostic module. The switching valve control module actuates a switching valve in a fuel system of a vehicle between a first position and a second position, the first position venting a suction side of a vacuum pump in the fuel system to an atmosphere, the second position sealing the suction side of the vacuum pump from the atmosphere. The pressure determination module determines a first pressure on the suction side of the vacuum pump when the switching valve is in the first position, and determines a second pressure on the suction side of the vacuum pump when the switching valve is in the second position. The fuel system diagnostic module selectively diagnoses a fault in the vacuum pump based on the first pressure and the second pressure.

Abstract: An engine system includes a status determination module and an open-loop fuel control module. The status determination module determines whether a first ignition fuse is in a failure state. The open-loop fuel control module disables a first plurality of fuel injectors and actuates a second plurality of fuel injectors based on a first air/fuel (A/F) ratio when the first ignition fuse is in the failure state, wherein the first ignition fuse and the first plurality of fuel injectors correspond to a first cylinder bank, and wherein a second ignition fuse and the second plurality of fuel injectors correspond to a second cylinder bank.

Abstract: A control module and method for operating the same includes a diurnal control valve module that opens a diurnal control valve (DCV) and an evaporative leak check module (ELCM) diverter valve control module that switches on an ELCM diverter valve. The control module includes a correlation module performs a correlation of a ELCM pressure signal and a fuel tank pressure signal and that generates a fault signal in response to the correlation when the DCV valve is open and the ELCM diverter valve is on.

Abstract: A system includes a control module, a valve control module, and a diagnostic module. The control module controls a valve of a variable intake manifold when the system operates in a first mode. The control module commands the valve to a first position when a desired airflow through the variable intake manifold is greater than a threshold and commands the valve to a second position when the desired airflow is less than the threshold. The valve control module controls the valve when the system operates in a second mode. The valve control module commands the valve to move from the second position to the first position when the desired airflow is less than the threshold. The diagnostic module determines an operating state of the valve based on whether the valve is detected at the first position a predetermined period after the valve control module commands the valve.

Abstract: An engine control system comprises a signal deviation module, a variation determination module, and a sensor diagnostic module. The signal deviation module receives a signal from a sensor monitoring an operating condition of an engine and determines a plurality of signal deviations. Each of the plurality of signal deviations is based on a magnitude of a difference between the signal at a first time and the signal at a second time. The second time is different than the first time. The variation determination module generates a variation value based on the plurality of signal deviations during a period. The sensor diagnostic module determines a state of the sensor based on the variation value.

Abstract: An intake air temperature (IAT) sensor diagnostic system may include an IAT determination module, a mass air flow (MAF) module, and a diagnostic module. The IAT determination module determines a measured IAT based on an IAT sensor. The MAF module determines a reference temperature based on a MAF sensor. The diagnostic module determines faults in the IAT sensor based on a comparison between the reference temperature and the measured IAT.

Abstract: A diagnostic system for an internal combustion engine includes an intake air temperature (IAT) determination module, a reference temperature determination module, and an adaptive learning module. The IAT determination modules determines a first IAT using an IAT sensor at a first time and determines a second IAT using the IAT sensor at a second time. The reference temperature determination module determines a first frequency based on a first voltage output of a MAF sensor at the first time and determines a second frequency based on a second voltage output of the MAF sensor at the second time. The adaptive learning module determines a temperature-frequency relationship based on the first IAT, the second IAT, the first frequency and the second frequency.

Abstract: An intake air temperature (IAT) sensor diagnostic module comprises a measured noise module, an expected noise module, an excess noise module, and an IAT fault detection module. The measured noise module measures noise in an IAT signal from an IAT sensor in a vehicle. The expected noise module determines expected noise based upon the IAT signal. The excess noise module determines an excess noise value based upon the measured noise and the expected noise. The IAT fault detection module diagnoses faults in the IAT sensor based upon a comparison of the excess noise value and a first predetermined value.

Abstract: A method of determining a barometric pressure of atmosphere, in which an internal combustion engine of a vehicle is located includes monitoring operating parameters of the internal combustion engine and the vehicle, determining a healthy status of an air filter of the internal combustion engine, and calculating the barometric pressure based on the operating parameters and the healthy status of the air filter.

Abstract: A control system comprising a wind condition determination module that determines a wind condition and a leak detection test control module that selectively diagnoses a vapor leak associated with a vehicle based on the wind condition. A method comprising determining a wind condition and selectively diagnosing a vapor leak associated with a vehicle based on the wind condition.

Abstract: An intake air temperature (IAT) sensor diagnostic system may include an IAT determination module, a mass air flow (MAF) module, and a diagnostic module. The IAT determination module determines a measured IAT based on an IAT sensor. The MAF module determines a reference temperature based on a MAF sensor. The diagnostic module determines faults in the IAT sensor based on a comparison between the reference temperature and the measured IAT.

Abstract: A method of evaluating intake air temperature (IAT) sensor rationality may include measuring a first intake air temperature associated with an engine using an IAT sensor when the engine is in a non-operating condition, determining a second intake air temperature associated with the engine using a hot wire air flow meter when the engine is in the non-operating condition, and indicating an IAT sensor fault when a difference between the first and second intake air temperatures exceeds a predetermined temperature limit.

Abstract: A control system and method of monitoring a condition of a catalyst in a catalytic converter includes commanding a first air/fuel ratio. A first signal is monitored from a first oxygen sensor and a second signal from a second oxygen sensor. A second air/fuel ratio is commanded. A first time is determined based on the first oxygen sensor reaching a first threshold voltage. A second time is determined based on the second oxygen sensor reaching a second threshold voltage. A differential area defined by the first and second signals between the first and second times is calculated.

Abstract: An intake air temperature (IAT) sensor diagnostic module comprises a measured noise module, an expected noise module, an excess noise module, and an IAT fault detection module. The measured noise module measures noise in an IAT signal from an IAT sensor in a vehicle. The expected noise module determines expected noise based upon the IAT signal. The excess noise module determines an excess noise value based upon the measured noise and the expected noise. The IAT fault detection module diagnoses faults in the IAT sensor based upon a comparison of the excess noise value and a first predetermined value.

Abstract: A fuel control system includes devices that generate parameter signals. The parameter signals include an engine runtime signal and at least one of an engine load signal, a temperature signal and a barometric pressure signal. A modification module generates a modification signal based on the parameter signals. A control module compensates for a current fuel volatility by adjusting a current air/fuel mixture of an engine based on the modification signal.

Abstract: A liquid fuel detection system for a fuel vapor system of a vehicle providing fuel vapor to an engine operating in closed loop includes an oxygen sensor that generates an oxygen signal based on an oxygen level in engine exhaust. An engine speed sensor generates a speed signal based on a speed of the engine. And a control module receives the oxygen signal and the speed signal, determines a fuel control factor based on the oxygen signal, determines a long term modifier based on long term changes of the fuel control factor, and detects the presence of liquid fuel in the fuel vapor system based on the fuel control factor, the speed signal, and the long term modifier.

Abstract: A method of monitoring air flow restriction in an air intake of an internal combustion engine includes recording a predetermined number of pre-throttle pressure samples, recording a predetermined number of mass air flow samples, which respectively correspond to the pre-throttle pressure samples and determining a slope based on the pre-throttle pressure samples and the mass air flow samples. Whether an air filter is inducing an air flow over restriction is determined based on the slope.

Abstract: A method of monitoring air flow restriction in an air intake of an internal combustion engine includes monitoring a plurality of manifold absolute pressure (MAP) samples and determining respective MAP thresholds corresponding to each of the MAP samples. Each of the MAP samples is compared to its respective MAP threshold. A percentage of failed MAP samples is determined based on the comparing and an over-restricted air intake condition is selectively indicated based on the percentage of failed MAP samples.

Abstract: A diagnostic control system for a purge valve that regulates fuel vapor flow from a fuel system into an intake manifold for an engine includes a calculation module and a malfunction module. The calculation module estimates a plurality of areas based on a plurality of pressure signals and calculates an average rate of increase of vacuum pressure in the fuel system during operation of the purge valve. The malfunction module determines whether the average rate of increase of vacuum pressure is within a predetermined range generating a purge valve functioning signal, and generates a purge valve malfunction signal when the average rate of increase of vacuum pressure is not within the predetermined range.