Abstract: A leak testing apparatus 1 includes a heat sensitive member 70 having a body 71 made of a material having high thermal conductivity. The body 71 is abutted against an outer surface of a workpiece 10 to close an opening of an inner space 11 of the workpiece 10. A pressure chamber 73 is formed inside the body 71 as arranged along the outer surface and as arranged over an area wider than the opening. Pressurized gas is introduced to the pressure chamber 73. Data on pressure change in the inner space 11 of the workpiece 10 is compensated based on inner pressure information regarding the pressure chamber 73, and leak judgment is made.

Abstract: A method and device for monitoring a fuel metering system, in which fuel is pumped from a low-pressure zone into a high-pressure zone. The pressure in the high-pressure zone is detected. An error is recognized on the basis of the pressure variation in the high-pressure zone. The type of error is recognized on the basis of the shape of a pressure drop curve. The variation of the pressure quantity over time is approximated using a function such as the hyperbolic function. The type of error is recognized on the basis of the quantity characterizing the function.

Abstract: A pressure sensor senses a pressure of a fuel vapor system at a fuel vapor passage. An electronic control unit executes a post-depressurization period flow diagnosis to determine whether the fuel vapor passage is clogged based on a behavior of the pressure in the fuel vapor system, which is sensed with the pressure sensor in a sealed state of the fuel vapor system after introduction of a negative pressure into the fuel vapor system.

Abstract: A leak diagnostic system for a vehicle comprises a tank pressure module and a leak diagnostic module. The tank pressure module selectively outputs first and second fuel tank pressures when an engine is shut down and when engine vacuum is greater than a predetermined engine vacuum, respectively. The leak diagnostic module selectively diagnoses a leak in a fuel vapor purge valve based on the second fuel tank pressure when the first fuel tank pressure is less than a first predetermined pressure.

Abstract: A test device for testing the integrity of a seal has a clear t-shaped liquid reservoir with three ends. A guide adapter is connected to the first end of the liquid reservoir and extends axially therefrom along an axis of the reservoir. A shaft adapter is connected to the second end of the body, opposite the first end. A test shaft with first and second ends extends axially through the first and second ends of the body and test and shaft adapters along the axis. The first end of the shaft is adapted to be connected to the rotating shaft of pump assembly.

Abstract: A test apparatus for testing fluid seals within an aerated fluid includes a container and a fluid located within the container. A plurality of seal coupons are submerged within the fluid in the container. An air supply is connected to the container to aerate the fluid within the container. Testing the seal coupons includes flowing air from the air supply through the fluid to contact the seal coupons. After the air has contacted the seal coupons then the plurality of seal coupons are removed from the fluid. A value for at least one characteristic of the seal coupons is then compared with a standard value.

Abstract: Systems and methods for performing leak testing on fuel system components in hybrid vehicles during engine-off operating conditions are disclosed. For example, a fuel tank may include a pressure accumulator which may be filled with fuel via a fuel pump in order to generate a vacuum which may be used to diagnose leaks in the fuel system.

Abstract: The present invention a portable universal electric radiator cap pressure tester, having a multiple of common radiator cap filler necks fixed on a dash board. The fixed filler necks simulate the filler neck openings on a vehicle's radiator or overflow reservoir. This allows the user the ability to quickly install a common radiator cap on the face of the tool and pressurize the radiator cap to its maximum recommended pressure. This gives the user the knowledge if a used radiator cap will hold its recommend pressure and provide a water tight seal during operation on a vehicle when the engine cooling system is under operating pressure.

Abstract: A method and device for determining the hydraulic leakage rate of liquid-conveying parts, in particular injection valves for internal combustion engines, place the liquid-conveying part into a test body, and the liquid-conveying part is charged with a test liquid under a particular pressure, and a carrier gas stream is provided in a flow duct of the test body, and a vapor mixture behind the liquid-conveying part is conducted to an analyzer, and a measurement and analysis are carried out, using the analyzer, of the hydraulic leakage rate of the liquid-conveying part via the concentration of test liquid in the vapor mixture, the carrier gas stream being brought in via a nozzle element close to the leakage point of the liquid-conveying part, and/or a heating of the vapor mixture being provided behind the liquid-conveying part for complete conversion into the gas phase.

Abstract: A method for detecting abnormality in a fluid supply line is provided that uses a fluid control apparatus with a pressure sensor so that abnormality of malfunction and sheet leaks of a plurality of valves incorporated into the fluid supply line can be checked easily, promptly and accurately by operating the flow rate control apparatus possessing the pressure sensor. Specifically, using a fluid supply line provided with the flow rate control apparatus possessing the pressure sensor equipped with a flow rate setting mechanism, a flow rate/pressure display mechanism, and/or a flow rate self-diagnosis mechanism, abnormality of the control valves, installed with the flow rate control apparatus and on the upstream side and downstream side thereof, is detected by using the pressure value displayed and/or the value diagnosed with a self-diagnosis mechanism of the flow rate control apparatus.

Abstract: In a method and a device for testing for leakage in a fuel injection valve of an internal combustion engine, a temperature quantity is determined that characterizes the temperature of at least a part of the fuel injection valve. On the basis of this temperature quantity, the presence of a leak is inferred.

Abstract: There is provided an anomaly judgment device that is capable of detecting an abnormal state of a system highly accurately and obtaining an accurate result. The anomaly judgment device may include a plurality of anomaly judgment devices for judging an anomaly of the system and, in cases where it is judged by the plurality of anomaly judgment devices that there is an anomaly, a judgment device judges that a system anomaly exists. Hence, even in the event of a localized abnormal state judgment by one anomaly judgment device or failure, a final judgment is not made based on that anomaly alone, and at least one other anomaly judgment is made, whereby erroneous judgments can be eliminated and a highly accurate anomaly judgment is possible.

Abstract: A test apparatus for an evaporative emission system includes a source of pressure (positive or negative), a sensor for sensing the pressure generated in the evaporative emission system, and an ECU which controls the operation of the source of pressure and receives signals from the sensor reporting the pressure in the vehicle evaporative emission system over time. The ECU compares the sensed data with the stored data representing standard baseline sample vehicles without any leaks to determine the presence of a leak in the evaporative emission system.

Abstract: A device for detecting a leak in a cylinder of an internal combustion engine, the internal combustion engine including a piston in the cylinder, the piston being attached to a crankshaft, includes a time interval determining unit which is designed to determine a first time interval in which the crankshaft passes a preset first angle segment before reaching the ignition top dead center of the piston in the cylinder, and to determine a second time interval in which the crankshaft passes a preset second angle segment after reaching the ignition top dead center of the piston in the cylinder, and a cylinder leak determining unit which is designed to detect a leak in the cylinder as a function of the first time interval and as a function of the second time interval.

Abstract: Apparatus and method for use in testing the fluid tightness of closed vessels or fluid systems, such as found in the pressurized cooling system of an internal combustion engine and the fluid transmission of an automobile. The apparatus is configured to detect and/or quantify fluid leakage from a fluid system that is under pressure, when in use, such as through imperfections in the housing or sealing structure of the fluid system whereby to warn the provider of such fluid system that a leakage condition exists.

Abstract: A manufacturing process, system, and method is described that facilitates the assembly and testing of a hydraulic manifold with integral closed loop pressure sensing and feedback.

Abstract: The invention relates to a method and a device for testing the tightness of a fuel tank of an internal combustion engine, in particular of a vehicle, with a pressure switch which communicates with the interior of the fuel tank, and a diagnosis means for testing the serviceability of the pressure switch by evaluating the switching status of the pressure switch. So that diagnosis of the pressure switch is possible even with the internal combustion engine shut off or the vehicle turned off and for internal combustion engines with exhaust gas turbochargers, it is proposed, according to the invention, that the diagnosis means test the opening behavior of the pressure switch when the temperature rises.

Abstract: An apparatus and method for leak detection through use of an adapter containing a chamber, an air pressurization port, and detection media instillation port. The apparatus is sealingly or relatively sealingly coupled to a turbo inlet air duct on an internal combustion engine under study, such that the apparatus chamber communicates with the engine's interior void. The apparatus permits pressurized air and detective media, such as smoke or fog, to be introduced through the chamber and into the void of an engine to determine the presence and location of engine system leaks.

Abstract: A leak diagnostic apparatus for a vaporized fuel processing system that purges vaporized fuel in a fuel tank of a vehicle is disclosed. The leak diagnostic apparatus comprises a leak diagnostic device, a fuel tank condition detection device and a determining device. The leak diagnostic device carries out a leak diagnosis of the vaporized fuel processing system while the engine is operating. The fuel tank condition detection device detects the conditions in the fuel tank. The determining device determines whether the leak diagnosis should be carried out based on predetermined conditions in the fuel tank.

Abstract: An apparatus for checking pressure leaks in a vehicle's heating and cooling system, such system including a radiator, top and bottom hoses, a water pump, a heater, a thermostat and connecting hoses. The apparatus comprises a test head for engagement with a neck of a radiator in place of a radiator cap. There is a gauge member in fluid communication with the test head for measuring an actual pressure on such cooling system. An air control valve is in fluid communication with the test head and the gauge member for regulating how much air pressure is going to such cooling system. The apparatus, further, has a handle control member that is in fluid communication with the test head, the gauge member and the air control valve and further is in fluid communication with a shop air hose for controlling how much air pressure is going to the air control valve.

Abstract: A method of detecting a leak in a fluid system, which includes a switch that changes state according to pressure in the fluid system. The method includes changing pressure in the fluid system with a pump assembly. The pump assembly includes a predetermined leak that is in fluid communication with the fluid system and that causes the switch to change state after a predetermined time period. The method also includes detecting a leak in the fluid system if the switch changes state within an amount of time less than the predetermined time period.

Abstract: This invention describes apparatus for and methods of testing cooling systems. The apparatus and method can be used for, among other things, pressurizing the cooling system either to a positive pressure or to a negative pressure, and for conducting temperature tests.

Abstract: Rate based monitoring includes performing test cycles on a monitored system when predetermined conditions are met. Completion of a test cycle is determined by timing a period that is at least as long as the longer of a time required to detect a correct operation of the monitored system and a time to detect a malfunction of the monitored system, the timing being reset if one or more of the predetermined conditions cease to be met. A count is kept of completed test cycles.

Abstract: A method of diagnosing a fuel tank leak in a fuel tank ventilation system, comprising a fuel tank, an accumulator for fuel vapors and a fuel tank ventilation valve opening out into an intake manifold of an internal combustion engine, wherein the fuel tank, the accumulator and the fuel tank ventilation valve are connected by way of a system of lines and wherein the accumulator has an aeration line with a check valve, the method comprising: immediately before turning off the internal combustion engine, closing the check valve and opening the fuel tank ventilation valve to generate a vacuum in the fuel tank ventilation system; acquiring a vacuum degradation at specifiable points in time when the fuel tank ventilation valve is closed; opening of the check valve in order to bring about a pressure equilibrium with the ambient pressure; renewed closing of the check valve; acquiring a pressure increase emerging over at least a specifiable time interval and determination of a compensation variable; and inference ab

Abstract: An apparatus and method for detecting cylinder leaks in an internal combustion engine includes a hose having an end configured for communication with a spark plug hole connecting to a cylinder to be tested and an end for attachment to a source of pressurized gas. Flow of pressurized gas into the cylinder is limited to the maximum amount of allowable gas leakage from the cylinder. The hose end configured for communication with the spark plug hole includes a resilient stopper sized to seal the end of the hose with respect to the spark plug hole when manually pressed into and held in the spark plug hole. If gas pressure builds up in the cylinder against the stopper during limited gas flow into the cylinder, leakage from the cylinder is below the allowed maximum leakage. Lack of gas pressure build-up indicates excessive cylinder leakage.

Abstract: A device for detecting a leak in a cylinder of an internal combustion engine, the internal combustion engine including a piston in the cylinder, the piston being attached to a crankshaft, includes a time interval determining unit which is designed to determine a first time interval in which the crankshaft passes a preset first angle segment before reaching the ignition top dead center of the piston in the cylinder, and to determine a second time interval in which the crankshaft passes a preset second angle segment after reaching the ignition top dead center of the piston in the cylinder, and a cylinder leak determining unit which is designed to detect a leak in the cylinder as a function of the first time interval and as a function of the second time interval.

Abstract: An electric motor or generator is used to spin the vehicle's internal combustion engine while the engine is not running, in order to draw a vacuum within the vapor control system. Vacuum bleed off is then monitored to determine if an unacceptable condition in the control system may exist. The evaporative fuel emissions test may be conducted either while the vehicle is at rest or while under way in an electric drive mode of operation.

Abstract: A technique is provided for detecting leaks in a fuel system such as an automotive fuel system. The technique complements an on-board diagnostics evaporative leak monitor that uses natural vacuum leak detection (NVLD). The technique utilizes the same switch and valve utilized by NVLD. Before engine shut-down, the system maintains a vacuum in the fuel tank and also provides a low-level purge flow. Upon engine shut-down, a timer is started and the NVLD switch is monitored to determine how long the vacuum is maintained in the tank. If the vacuum is maintained longer than a predetermined time period, then the system determines that the leak test is passed. If the vacuum decays faster than the predetermined time period, then the NVLD test is performed and system determines that the system passes the leak test if the NVLD test is passed.

Abstract: An intake manifold air leak determination system and method for an internal combustion engine including an intake manifold fluidly connected to a plurality of cylinders of the engine and a plurality of fuel injection valves for injecting fuel for the cylinders. Each of the plurality of fuel injection valves corresponds to a respective one of the plurality of cylinders. A fuel cutoff indicating module determines that fuel has been cut from one or more of said plurality of cylinders due to certain operating conditions of the internal combustion engine. An air leak detection module determines whether a significant air leak is occurring at the intake manifold. An air leak fuel cutoff module cuts off fuel supply to the fuel injection valves when the air leak detection module determines that a significant air leak is occurring at the intake manifold.

Abstract: The present invention includes a method and system using dynamic pressure measurements for determining a presence, location, and size of a leak in a chamber of a body. The method includes sealing a plurality of ports of the chamber, pressurizing the chamber with a fluid, measuring a dynamic pressure at each of the plurality of ports, and analyzing the dynamic pressure measured at each of the plurality of ports to determine a presence, location, and/or size of the leak. The location of the leak can be determined by analyzing magnitude and/or phase values from a generated frequency response function matrix, interpolating between two of the plurality of ports, triangulating between three of the plurality of ports, and/or analyzing a rate and profile at which the pressure decays at each of the plurality of ports to determine the location of the leak.

Abstract: A target pressure value is determined during the learning mode. Subsequent pressure values are then compared to the target value. For example, a first connection is tightened in a conventional manner, while its pressure is monitored during the learning mode. If the tightening process went well, then an operator pushes a button that tells the monitor to remember how much pressure was used on the tongs to tighten the first connection. The pressure value of that first joint then becomes the target pressure value for any subsequent joints. As additional joints are tightened, the pressure applied to the tongs is monitored and compared to the first one to ensure that all the joints are as good as the first one within an allowable tolerance.

Abstract: An abnormality determining apparatus of a fuel vapor processing system is provided. The system includes a canister for temporarily reserves fuel vapor generated within a fuel tank and a fuel vapor path for discharging the fuel vapor to an engine intake passage. When it is determined that there is a leak abnormality in the fuel vapor path, a pump is operated to discharge air from the fuel vapor path to the outside through the canister. When the pump is operated, a detector detects a pressure in the fuel vapor path as an actually measured pressure. A determining section determines whether there is a leak abnormality. The determining section sets a first determination pressure and a second determination pressure that is higher than the first determination pressure. The determining section determines that there is no leak abnormality either when a first condition is met or when a second condition is met.

Abstract: Rate based monitoring includes performing test cycles on a monitored system when predetermined conditions are met. Completion of a test cycle is determined by timing a period that is at least as long as the longer of a time required to detect a correct operation of the monitored system and a time to detect a malfunction of the monitored system, the timing being reset if one or more of the predetermined conditions cease to be met. A count is kept of completed test cycles.

Abstract: Method to test for a leak in a fuel tank system of a motor vehicle with the following steps: a) a fuel tank is cut off during the overrun by means of at least one cutoff device (7, 9b), and the pressure, which builds up in the fuel tank within a specifiable time interval is acquired; b) if a specifiable maximum pressure or a specifiable vacuum threshold is not achieved, said cutoff device (7, 9b) is opened and closed again after a specifiable time period, and a vacuum is produced and acquired in a subsequent vacuum phase, and a parameter, which characterizes the leak tightness, is determined and evaluated from the vacuum achieved within a specifiable time period and the overpressure, which is achieved, and the test for a leak is concluded; c) if the specifiable maximum pressure is achieved, a parameter characterizing the leak tightness is determined from the acquired overpressure and the specifiable overpressure threshold and is compared with a specifiable reference value and for the case that the determin

Abstract: An ECU drives a pump in a first stage at a first pumping capacity. The ECU drives the pump in a second stage after the first stage at a second pumping capacity, which is lower than the first pumping capacity. The second pumping capacity is set such that when at least one leak hole, which forms a predetermined total opening cross sectional area, exists in the purge apparatus, the driving of the pump at the second pumping capacity substantially maintains a predetermined reference pressure in the purge apparatus. The ECU diagnoses whether a leak hole exits in the purge apparatus based on the pressure measured with the pressure sensor in view of the predetermined reference pressure at the time of driving the pump in the second stage at the second pumping capacity.

Abstract: A detector for detecting evaporated fuel leakage from a fuel tank is connected to the fuel tank through a canister for absorbing evaporated fuel. When an engine is not in operation, air in the fuel tank is sucked by a pump installed in the detector. If the pressure in the fuel tank decreases to a predetermined level, it is determined that the evaporated fuel leakage is within a permissible range. An orifice passage, formed in the detector, connecting a tank passage to a sensor passage communicating with a sensor chamber where a pressure sensor is disposed is slanted relative to the tank passage to shorten the passage distance up to the pressure sensor. Further, the orifice passage is connected to the sensor passage at an obtuse angle to reduce a pressure loss in the passages. Thus, the leakage of the evaporated fuel is surely detected while making the detector compact.

Abstract: A leak check apparatus performs a leak check of a fuel vapor processing apparatus based on a change in a negative pressure in a purge line during leak down. The pressure change during leak down is corrected by measuring an amount of vapor generated after the purge line is opened to the atmosphere. A first pressure change rate of the purge line is measured after a predetermined negative pressure is applied to the purge line, and the purge line is sealed at the negative pressure. A second pressure change rate of the purge line is measured after the first pressure change rate of the purge line is measured, the cut valve is opened to expose the purge line to the atmosphere, and the purge valve and the cut valve are closed to seal the purge line at the atmospheric pressure. The second pressure change rate measurement does not begin until the degree of pressure increase in the purge line exceeds a predetermined reference value.

Abstract: A control system and method for detecting a hydraulic system leak in an engine includes a pressure sensor that senses a first pressure reading of a hydraulic fluid supply at a first time and a second pressure reading of said hydraulic fluid supply at a second time. A comparison module calculates a pressure ratio based on the first and second pressure readings and signals a fault condition based on a relationship between the pressure ratio and a pressure threshold.

Abstract: The invention relates to a method for checking the gastightness of a motor vehicle tank ventilation system consisting essentially of a fuel tank, an adsorption filter, a ventilation line with a pressure sensor, a fresh air line with an adsorption filter check valve (AAV), and a regeneration line with a tank ventilation valve (TEV) to the internal combustion engine. To compensate for the outgassing of fuel, the total diagnosis time tD is formed from the negative pressure buildup time t1 and the negative pressure decay time t2 as a measure of the tightness of the tank ventilation system and is compared to a corresponding diagnosis time threshold tDS.

Abstract: A system for detecting contamination of an air filter for an internal combustion engine includes an air pressure sensor disposed downstream of the air filter, an air flow sensor disposed in an air intake system of the engine, and a control module in communication with the air pressure sensor and the air flow sensor. The control module is configured to estimate an atmospheric pressure based on a signal received from the air pressure sensor. The control module is further configured to determine a contamination level of the air filter based on an air flow rate provided by the air flow sensor and a pressure drop across the air filter based on a pressure difference between the estimated atmospheric pressure and a second pressure measurement from the air pressure sensor that corresponds to the provided air flow rate.

Abstract: A valve test apparatus, a solenoid valve test method and a venturi valve test method are provided. The valve test apparatus may include a gas supply unit, a solenoid valve holding unit, a first measurement unit, a venturi valve holding unit, a second measurement unit, a timer unit and/or a power supply unit. The solenoid valve holding unit may be connected to one end of the gas supply unit. The first measurement unit may be connected to the solenoid valve holding unit. The venturi valve holding unit, on which a venturi valve to be tested may be arranged. The venturi valve may be selectively connected to the solenoid valve holding unit together with the first measurement unit. The second measurement unit may be connected to the venturi valve. The timer unit may measure a time interval between when the solenoid valve is activated and when a measured value by the first measurement unit or second measurement unit is equivalent to a desired value.

Abstract: A compact (e.g., hand held) vacuum generator having particular application for creating a vacuum within the evaporative emissions system (e.g., a gas tank) of a motor vehicle so that a vacuum-decay test can be performed to test the system for leaks while mitigating the hazardous effects of potentially explosive hydrocarbon vapors. The vacuum generator includes a spool valve that has an internal passage and is capable of sliding through a spool valve bore in response to a pushing force. During an at-rest stage of the spool valve within the spool valve bore, the system to be tested is disconnected from the vacuum generator. During a transition stage of the spool valve within the spool valve bore, inlet gas under pressure is blown through the internal passage of the spool valve to the atmosphere by way of a vacuum generating venturi, whereby a vacuum begins to form in a vacuum passage.

Abstract: A fuel vapor purge system is configured to execute a highly accurate leak diagnosis with respect to a fuel vapor leak. After the engine is stopped, the temperature of the fuel vapor rises temporarily and then decreases until it reaches the outside ambient temperature. During this period, the purge line is closed off and a purge line pressure decreasing rate is detected when the purge line pressure is slightly above atmospheric pressure. The detected purge line pressure decreasing rate is then compared to a threshold value. The purge system is diagnosed as “normal” if the purge line pressure decreasing rate is equal to or larger than the threshold value and as “leaking” if the purge line pressure decreasing rate is less than the threshold value.

Abstract: A method and apparatus for developing a test for determining if an engine has oil seal leaks. The engine is charged with a predetermined pressure of air and monitored by a leak tester. A digital valve is set to provide a certain leak rate based upon signals received from a digital valve controller. Thereafter, based upon signals received from a PC and a main control unit, a variety of trials are completed. The results and programs are stored in the PC. Results of the trials allow an optimized testing program to be selected that would be best suited for use on a manufacturing assembly line.

Abstract: A method for pressure testing an engine to detect possible oil seal leaks. The engine is charged with a predetermined pressure while air pressure is also applied to an exhaust gas recirculation (EGR) valve intake port to offset leakage inherent in the EGR valve. Thereafter, a pressure drop in the engine pressure is used to determine whether an oil seal leak may be present. Applying pressurized air to the EGR valve intake port compensates for EGR valve leakage and prevents the EGR valve leakage from masking possible oil seal leaks, thereby making the system more sensitive to such potential oil seal leaks.

Abstract: An evaporated fuel leak detector detects leakage of an evaporated fuel generated in a fuel tank. The detector includes: a differential pressure valve, a pump for sucking a detection port side to reduce pressure on a fuel tank side, and pressure detection means for detecting pressure on a detection port side. The valve includes a detection port connecting to a fuel tank side, an atmosphere port opened to atmosphere, a pressure chamber and a valve member displaceable in accordance with differential pressure between the detection port and the pressure chamber for connecting and disconnecting a connection between the detection port and the atmosphere port. The valve member disconnects between the detection port and the atmosphere port in a case where pressure of the pressure chamber becomes larger than pressure of the detection port by a predetermined pressure.

Abstract: The invention relates to a method for operating a combustion engine (1) comprising a fuel-driven heat engine (5), which permits a differentiation of faults during the supply of fuel. To this end, the fuel is supplied under pressure to the heat engine (5) via a fuel supply (10). A pressure reduction speed in the fuel supply (10) is determined, and a fault is inferred based on a comparison of the pressure reduction speed with a predetermined threshold value.

Abstract: A leakage detecting device is connected to an evaporating fuel processing apparatus to detect leakage of evaporating fuel in a ventilation apparatus that includes an electric pump, a fuel tank, and a filter. The electric pump includes a pump portion and a motor portion. The pump portion is capable of generating at least one of pressurizing force and de-pressurizing force. The motor portion drives the pump portion. The filter absorbs fuel evaporating in the fuel tank. The leakage detecting device generates pressure difference between the inside of the ventilation apparatus and the outside of the ventilation apparatus in accordance with the pressurizing force and the de-pressurizing force generated using the electric pump to detect a leakage condition of the ventilation apparatus. The leakage detecting device includes a rotation speed controlling means that controls rotation speed of the motor portion at a predetermined rotation speed.

Abstract: A system and method for evaluating the integrity of a leak detection test for a purge valve of a fuel system in a vehicle reduces or eliminates false failures. The method is executed on an engine control module (ECM) and is configured to determine when vehicle soak conditions meet first criteria conducive to fuel vapor condensation in the fuel tank. The first criteria include a predetermined temperature drop in ambient air temperature between successive drive cycles. The ECM is further configured to determine when a vehicle maneuver meets second criteria indicative of the capability of the maneuver to initiate fuel slosh in the fuel tank, to thereby establish a trigger event. The ECM is further configured to determine, after the trigger event, the maximum slope of a fuel tank vacuum increase. The ECM is still further configured to produce a slope ratio as a function of the maximum vacuum increase slope and a reference vacuum slope corresponding to a slope that is unaffected by any slosh/condensation events.

Abstract: Concentration measurement is performed multiple times from a period in which pressure in a purge device increases due to generation of fuel vapor after operation of an engine is stopped. A concentration stabilization period, in which a change in the fuel vapor concentration is equal to or less than a reference value, is calculated based on results of the multiple times of the concentration measurement. Leak diagnosis is performed during the concentration stabilization period. As a result, even if a period for the pressure in the purge device to stabilize fluctuates due to an environment in which a vehicle is located, the leak diagnosis can be performed immediately when the pressure in the purge device stabilizes and a state suitable for the leak diagnosis is reached.