Abstract: A diesel engine emergency shutoff device for use on a regularly aspirated or turbocharged diesel engine. The device is mounted between on the engine's air intake tube and utilizes a closure valve biased to the open position by biasing means and actuated to the closed position by engine vacuum.

Abstract: A system and method of monitoring the purge flow in an evaporative emission control purge system of a motor vehicle. Signals indicative of engine speed, fuel control and automatic idle speed position are measured and used to determine whether the purge flow system is operating properly. With purge flow activated, the amount of purge flow is increased in accordance with a ramping rate and the measured signals are monitored to determine whether or not a change occurs in any one of the engine speed, fuel control and AIS position signals.

Abstract: A method and device for generating a simulated signal relating to a temperature in the exhaust system of a motor vehicle. By means of a characteristic curve or a characteristic diagram, a signal for a steady state exhaust gas temperature is generated as a function of the flow rate of gas through the internal combustion engine of the motor vehicle. This signal is further processed to generate a signal for a rapid portion and to form a signal for a slow portion of the exhaust gas temperature. The signals for the two portions are superimposed with a prescribable weighting to generate a signal for the exhaust gas temperature. The signal for the slow portion can be logically connected, before the superimposition, to a correction value which depends on the speed of the vehicle.

Abstract: A method and device for forming a signal relating to a temperature in the exhaust system of an internal combustion engine. The method can be used, for example, to form a signal for the exhaust gas temperature upstream of the catalytic converter, a signal for the temperature in the catalytic converter, or a signal for the temperature downstream of the catalytic converter. The first step is to form a signal for a steady-state exhaust gas temperature as a function of at least one operating characteristic of the internal combustion engine. This signal can be subjected to a series of corrections in order to take into account parameters such as the efficiency of the internal combustion engine, the air/fuel ratio, the temperature of the intake air, the mixture flow rate, the vehicle speed, a possibly activated cylinder cutout, and the presence of condensed water in the exhaust system.

Abstract: An apparatus for quickly and virtually complete purging of seawater from combustion chambers of an outboard engine that has been submerged or a submersible outboard engine. A poppet valve is incorporated in the combustion chamber portion of the engine head. The valve has discharge ports radially disposed around its periphery so that when the poppet valve is pneumatically operated, the ports permit the discharge of entrapped water from the combustion chamber as the engine is turned over.

Abstract: In a fuel system for motor vehicles, comprising a fuel tank, a fuel filler pipe with an opening into the tank, a first gas conduit, one end of which is positioned within the tank and whose opening determines the highest fuel level in the tank when filling the tank, and a second gas conduit which extends from an expansion space in the tank above said highest fuel level to a filter device; the improvement wherein the second gas conduit (4) includes a restriction device (9) which is so arranged that the flow resistance of the gas flow in the direction from the tank (1) to the filter device (8) is greater than in the opposite direction, and a pressure sensor (11) arranged to detect the pressure in the gas volume above the surface (N) of the fuel.

Abstract: The specification relates to an intake manifold having an increased compaction. In this intake manifold, at least one fragile zone is formed parallel to its longitudinal axis in its wall. Crash impact is absorbed and the volume of the intake manifold decreases after crashing, because its cross section is crushed. The intake manifold of this invention has an increased compaction and can prevent the structure around fuel injection valves from breaking.

Abstract: A fuel pump for a high-pressure fuel injection system includes a high-pressure fuel pump 4 for supplying high-pressure fuel to injectors 8 for injecting high-pressure fuel into cylinders of an engine, a pressure control valve 10 for controlling the fuel pressure of the high-pressure fuel pump 4, a high-pressure fuel supply pipe 16 connecting the high-pressure fuel pump 4 and the injectors 8, a high-pressure fuel control pipe 17 connecting the injectors 8 and the pressure control valve 10, and a pump-control valve communication passage 18 formed to communicate the high-pressure fuel pump 4 with the pressure control valve 10 and bypass the injectors 8, the sectional area of the pump-control valve communication passage 18 being smaller than those of the high-pressure fuel supply pipe 16 and the high-pressure fuel control pipe 17.

Abstract: An evaporative fuel-processing system for an internal combustion engine comprises an evaporative emission control system including a canister having an air inlet port formed therein for introducing atmosphere into the canister and accommodating an adsorbent for adsorbing evaporative fuel generated in the fuel tank. A charging passage connects between the canister and the fuel tank. A two-way valve is arranged across the charging passage. A purging passage connects between the canister and the intake system. A purge control valve is arranged across the purging passage. An ECU carries out leak-checking of the evaporative emission control system. A negative pressure responsive-type bypass valve is arranged across a bypass passage bypassing the two-way valve. A negative pressure responsive-type vent shut valve is disposed to open and close the air inlet port of the canister.

Abstract: When refueling is started, a purge valve is closed, and power is supplied to a coil of a solenoid so that a constant pressure operating valve of an atmospheric escape valve is opened. When the temperature of the fuel tank rises while an engine is at a stop, fuel evaporation gas generates and the pressure within the fuel tank increases. When the differential pressure between the in-tank pressure and the atmospheric pressure increases, a first communication passage is opened, and the pressure is released to the outside. Thus, the pressure within the fuel tank can be maintained at an appropriately high pressure level while the vehicle is at a stop, and the quantity of the fuel evaporation gas generating while the vehicle is at a stop can be controlled.

Abstract: A flow of fuel is prevented from entering the intake manifold via the manifold vacuum passage in a fuel injection system having a source of liquid fuel under pressure in fluid communication with a least one fuel injector 28 mounted in an engine intake manifold 20 and a pressure regulator 68 having a first pressure chamber 82 in fluid communication with the source of pressurized fuel, a second pressure chamber 84 in fluid communication with the intake manifold 20, and a diaphragm 86 sealingly engaged therebetween for maintaining a predetermined pressure differential between the pressure chambers by an apparatus 78 operatively connected between the second pressure chamber 84 and the intake manifold 20 which prevents the flow of fuel from the second pressure chamber 84 to the intake manifold 20 in response to a pressure differential between the second pressure chamber 84 and the intake manifold 20 above a predetermined value.

Abstract: An electromagnetically driven valve control system for an internal combustion engine having at least one intake valve and at least one exhaust valve, and a starter for starting cranking of the engine. A CPU controls an energization time/timing control circuit section to electromagnetically drive at least one of the at least one intake valve and the at least one exhaust valve. The CPU detects a starting signal indicative of starting of the cranking of the engine, and a timer measures a time period elapsed after the starting signal is detected. An inhibiting time period is set, over which the operation of the starter means is inhibited, and the at least one of the at least one intake valve and the at least one exhaust valve is driven in a valve closing direction when the starting signal is detected. The operation of the starter is permitted when the time period elapsed after the starting signal is detected exceeds the inhibiting time period.

Abstract: The evaporative emission control system in the present invention is equipped with a fuel tank and a canister connected to the fuel tank, and a pressure sensor connected to the canister and the fuel tank via a three-way switching valve. The pressure sensor can be selectively connected to the canister and the fuel tank by switching the position of the three-way switching valve. The control circuit, which may consist of a known type of microcomputer, detects failures in the system based on the smoothed pressure values of the canister and the fuel tank. The smoothed pressure value is obtained by smoothing fluctuations of the pressure detected by the pressure sensor. Since the characteristics of the fluctuations of the pressure in the canister and the fluctuations of the pressure in the fuel tank are different, the control circuit changes the degree of smoothing fluctuation when obtaining the smoothed pressure value of the canister and when obtaining the smoothed pressure value of the fuel tank.

Abstract: A method of controlling operation of a compressed natural gas vehicle as a function of a predetermined level of methane in the ambient. Vehicle ignition is turned off when a predetermined level of methane is sensed in the ambient.

Abstract: A procedure to control the drive unit in motor vehicles wherein: the maximum engine performance characteristic is determined; as a minimum engine performance characteristic, a reference performance characteristic is specified by how drive resistance depends on vehicle speed at a medium payload of the motor vehicle; above the reference performance characteristic, a first performance characteristic which is dependent on actual driving speed is defined and allocated a minimum assessment value; between this first performance characteristic and the maximum engine performance characteristic, a second performance characteristic which is also dependent on actual driving speed is defined and allocated a maximum assessment value; the current engine performance is determined; current assessment values are determined by comparing current engine performance to the first performance characteristic and the second performance characteristic; the current assessment values, as continuously determined, are filtered over time in

Abstract: A high pressure fuel system includes a combination bypass and safety pressure release valve across the high pressure fuel pump. The combination valve allows the feed pump to directly provide fuel to the system before the high pressure pump reaches full output pressure. The valve also releases overpressure in the system when the high pressure pump is deadheaded. The combination valve includes a check ball which allows fuel to flow from its input to its output when the pressure is greater at its input than at its output.

Abstract: A method and apparatus for protecting an engine from overheating. The apparatus comprises a cylinder head temperature sensor operably coupled to sense the temperature of the cylinder head and a control system operably coupled to the cylinders and the cylinder head temperature sensor such that when the temperature of the cylinder head exceeds a maximum level the control system deactivates one or more of the cylinders and rotates the deactivation of one or more engine cylinders such that no one cylinder is constantly fired thus providing engine cooling by drawing fresh air through the deactivated one or more cylinders.

Abstract: In a pump control circuit, if a battery voltage declines to a voltage level lower than that required to insure a constant voltage, a low-voltage detection circuit outputs a low voltage detection signal. In the case of the decline in the battery voltage, an NOR circuit outputs the conversion signal from an internal logic section, and a pump control signal bypassing the internal logic section, giving priority to the latter signal. A motor drive circuit turns FET ON and OFF in accordance with the output signal of the NOR circuit. According to ON/OFF of the FET, the intermittent control of the current from the battery to the pump drive motor is performed.

Abstract: An apparatus for checking a tank venting system for leaks that serves to vent a fuel tank of a motor vehicle whose engine has a intake tube. The apparatus has an absorption filter connected to a ventilation line, which can be closed by means of a shutoff valve, and pressure producing devices for the production of an overpressure in the fuel tank. The pressure producing devices are embodied as actuatable by means of the vacuum in the intake tube in order to be able to forego the separate electromechanical drive devices for the pressure producing devices which have been necessary in the prior art.

Abstract: A liquid fuel burning apparatus having a system for interrupting operation of the apparatus during refueling. The apparatus has a spring biased cable mounted at one end within a slot located proximate a refueling opening. A fuel tank cap has a projection which is adapted to contact a portion of the cable disposed within the slot. When the cap is fully seated on the refuelling opening of the fuel tank, the cable is depressed within the slot by the projection. When the cap is removed, the biasing device causes the cable to move to a released position. For example, this movement of the cable in a specifically disclosed heater embodiment is transmitted via the cable to a wick retracting mechanism which responds by lowering the wick into the reservoir and extinguishing any flames.

Abstract: A system 10 for controlling the operation of a propane powered vehicle engine includes a gas sensor 28 for providing a fuel rich signal and a fuel lean signal to a controller 20. The controller is also responsive to a tachometer 26 which senses the engine rpm. When the engine speed is in excess of a preselected value and is not decelerating, the controller generates an unacceptable engine operation signal if the period of duration of the fuel rich signal exceeds a preselected value. A warning unit 32 is provided for alerting the operator of a service required signal from the controller. A fuel shutoff device 30 automatically terminates the fuel supply to the engine in response to a fuel shutoff signal from the controller. The method of the invention allows for vehicle startup after the fuel shutoff device has been activated. The invention is particularly well suited for requiring a propane powered vehicle engine to output an acceptable level of carbon monoxide in the exhaust gas.

Abstract: In a diagnosing apparatus and method for an internal combustion engine having a variable valve timing control system, the apparatus and method diagnose whether the variable valve timing control system actually switches the valve timings according to a switching between an operation and non-operation of the variable valve timing control system, utilizing a variation occurrence in an intake air pulsation in response to the switching between an operation mode and non-operation mode of the variable valve timing control system.

Abstract: An electronic control apparatus for an engine of a vehicle has a first CPU for fuel control which controls the amount of fuel to be supplied to the engine and a second CPU for throttle valve control which outputs a driving signal to an actuator which operates to open or close the throttle valve disposed in an intake pipe to the engine. The apparatus has an opening degree computing member which is provided in the first CPU to compute an opening degree of the throttle valve based at least on an amount of depression of an accelerator and then to output a result thereof as an opening degree signal. The first CPU and the second CPU are connected together by a communication line which transfers the opening degree signal from the opening degree computing member from the first CPU to the second CPU.

Abstract: A cam shaft of an engine is provided with a timing change mechanism (VVT) which is driven by hydraulic pressure to alter the timing of a intake valve (valve timing). This VVT is controlled to change the valve overlap of the intake valve and an exhaust valve, thereby adjusting the suction and exhaust in and from a combustion chamber. To control the VVT, an electronic control unit (ECU) computes a target value for the valve timing in accordance with the running condition of the engine and controls the supply of the hydraulic pressure to the VVT based on the target value. The ECU determines the level of the actual hydraulic pressure given to the VVT. When the actual valve timing does not lie in a predetermined range with respect to the target value, the ECU determines that an abnormality has occurred in the VVT, and executes a predetermined fail safe routine. When the hydraulic pressure is equal to or smaller than a reference value, the ECU suppresses VVT malfunction determinations.

Abstract: A pressure intensified fuel injector incorporates an overtravel safety feature which prevents fuel flow through the high pressure chamber of the intensifier upon injection nozzle failure, thereby preventing further and uncontrolled injection events in the event of such failure. The overtravel safety feature is preferably formed by dimensioning the high pressure plunger of the intensifier such that, upon overtravel of the plunger in the event of injector nozzle failure, a side surface of the plunger blocks a fuel inlet port of the high pressure cylinder of the intensifier, thereby preventing further fuel flow through the high pressure cylinder. The intensifier having the overtravel safety feature can be used in either accumulator-type or non-accumulator-type injectors.

Abstract: A fluid temperature monitor comprising a thermosensing unit which is of a size and shape so that it may be readily inserted between the male exit from the fluid coolant pump and the radiator hose connected thereto, thus permitting universal installation in internal combustion engines.

Abstract: A process for indicating abnormal conditions in a motor vehicle by inducing misfires through the absence of fuel supply. The fuel supply is interrupted cylinder by cylinder in such a manner that the supply is interrupted during a proportion of the total number of injection cycles of the respective cylinders during a first fuel supply sequence, after which the next cylinder interrupts the fuel supply for a proportion of the total number of injection cycles of that cylinder during a subsequent fuel supply sequence. The interruptions of the fuel supply take place preferably as a predetermined number of injection cycles during a fuel supply sequence, and when each injection supply sequence is of equal length or includes a certain number of injection cycles. This can give rise to a distinct signal quality from the engine, in the form of irregular, uncomfortable engine running, while each individual cylinder is subjected to the least possible disturbance, apart from an ideal operating condition.

Abstract: A method for checking the operability of a tank-venting system for a motor vehicle having an internal combustion engine (10), the system including an adsorption filter (14) having a venting opening (17) at its venting end and having a connecting line (16) to a tank (15) as well as a tank-venting valve (13) which is connected into a connecting line (12) between the intake pipe (11) of the engine and the intake end of the adsorption filter, characterized in that:a difference pressure (Dp) is measured which is a measure for the pressure difference between the venting end and the intake end of the adsorption filter; and,a conclusion is drawn as to inadequate throughput capacity of the adsorption filter when the measured difference pressure exceeds a threshold value (Dp.sub.-- SW).With this method, as with similar methods provided in the disclosure, it is possible for the first time to check the throughput capacity of an adsorption filter in a tank-venting system.

Abstract: A protection system for a pressure-charged (supercharged) combustion engine. In normal operation, the pressure-charging is controlled and/or regulated to a specifiable desired setpoint value P Setpoint. For the case of over-boosting of the internal combustion engine, various protective measures are provided, which are used in dependence upon the extent of over-boosting. In the case of a first protective measure, the control and/or regulation of the pressure-charging is switched off, and a final controlling element, which influences the pressure-charging, is adjusted to a predeterminable position. In the case of a second protective measure, the fuel metering to individual cylinders is interrupted in accordance with a predetermined skip pattern. If it is not possible to achieve an adequate reduction in the pressure-charging by this means, the system switches successively to further skip patterns with a higher skip frequency.

Abstract: Operation of a fuel vapor control apparatus having a canister and a fuel vapor purging passage is detected occasionally by a pressure sensor which is disposed in a fuel tank of an engine. The sensor detects pressure changes in the purging passage caused by closing or opening the passage between the canister and a suction pipe of the engine, and by introducing or by interrupting the air flowing into the canister. A computer calculates signals generated by the sensor and decides whether or not any failure has occurred in the fuel vapor control apparatus. An air intake unit which has an air filter and an air switching valve is detachably installed close to the canister. When the air switching valve is controlled to introduce the air into the canister, the air passes the filter before the switching valve so that the valve may not be subject to dust or foreign particles contained in the air and good sealing of the valve is ensured for long time.

Abstract: An on-board diagnostic system for an evaporative emission control system of an internal combustion engine powered vehicle employs a positive displacement reciprocating pump to create in evaporative emission space a pressure that differs significantly from ambient atmospheric pressure. The pump is powered by using engine intake manifold vacuum to force an intake stroke during which both an internal spring is increasingly compressed and a charge of ambient atmospheric air is created in an air pumping chamber space. Vacuum is then removed, and the spring relaxes to force a compression stroke wherein a portion of the air charge is forced into the evaporative emission space. The pump operation is under the control of a computer that contains an algorithm for operating the pump in particular modes of operation to arrive at a decision concerning integrity of the evaporative emission space against leakage.

Abstract: A secondary brake light switch comprising a hollow housing having a first end and a second end; an electrically conductive plunger slidably disposed within the housing; a switch coupled to the second end of the housing with switch having an input terminal facing the plunger and an output terminal adapted to be coupled between brake lights of a vehicle and their associated power source; a generally hollow vacuum valve having a first end coupled to first end of the housing, a second end adapted to be coupled to a vacuum system of a vehicle, and a diaphragm disposed within the vacuum valve with the diaphragm actuated when a high vacuum condition is created at the second end of the housing when a vehicle is accelerating and the diaphragm de-actuated when a low vacuum condition is created at the second end of the housing when a vehicle is idling; and an extension mechanism coupled between the diaphragm and the plunger for allowing the plunger to contact the input terminal of the switch when the diaphragm is de-act

Abstract: An apparatus and method for sensing the failure of hydraulically-actuated electronically-controlled fuel injector in a combustion engine is disclosed. An electronic controller senses the pressure of the hydraulic actuator fluid prior to injection and samples the pressure throughout a subsequent injection cycle. If the samples show an oscillation in the pressure of the hydraulic actuator fluid, then the injector has fired. Otherwise, the injector has failed.

Abstract: An evaporative purge flow monitoring system is provided for use in a motor vehicle having an internal combustion engine, a fuel tank, and an evaporation canister in communication with the fuel tank and the engine for trapping and subsequently reusing fuel vapor dispelled from the fuel tank. The evaporative purge flow monitoring system includes a vapor management valve interposed between the engine and the evaporation canister. An Electronic Engine Control (EEC) assembly is further provided in communication with the vapor management valve and the engine wherein the EEC assembly is provided with a test logic to determine satisfactory operation of the vapor management valve. The test logic determines whether the vapor management valve is defective based on either the presence of significant fuel vapor as determined by the test logic or a change in an engine performance parameter generated within the EEC assembly without requiring a separate sensor when the vapor management valve is temporarily closed.

Abstract: An evaporative emission control system for an internal combustion engine includes a canister for adsorbing evaporative fuel generated in the fuel tank, a communication passage connecting between first and second adsorbent chambers defined in the canister, a first introducing passage for introducing the generated evaporative fuel into the canister on an occasion other than at fueling, a purging passage for purging the evaporative fuel adsorbed into the canister to the intake passage, and an air-inlet passage communicating with the atmosphere. The first introducing passage, the second air-inlet passage and the purging passage are connected to the first adsorbent chamber. A second introducing passage is connected to the second adsorbent chamber, for introducing the evaporative fuel thereinto at refueling, and an additional passage having a cross sectional area larger than that of the air-inlet passage and communicating with the atmosphere is connected to the first adsorbent chamber.

Abstract: Differential flow sensing through respective flow path portions of a system for detecting leakage from an evaporative emission control system. A series flow path comprises a first flow sensor for sensing the entire output flow of an impeller pump used to positively pressurized the system under test, a second sensor in a portion of the series flow path that is downstream of the first flow sensor, and a calibrated orifice downstream of the second flow sensor. A branch circuit to the evaporative emission space under leakage test tees into the aforementioned series circuit between the first flow sensor and the second flow sensor. A differential amplifier receives signal from the respective sensors. Any difference in sensed flows, once the pressure has been brought to a predetermined pressure, is output by the differential amplifier to signify leakage in an amount correlated with the sensed difference in the flows.

Abstract: A protective device is provided for discontinuing the operation of an internal combustion engine having two banks of cylinders, each cylinder bank having an associated pressurized cooling circuit. Each cooling circuit has a separate pump which circulates liquid coolant by increasing the coolant fluid pressure at the pump outlet relative to the pump inlet.

Abstract: A fail-safe system and method for automobile fuel tank wherein when the fuel filler cap is opened at fueling and the pressure in the fuel tank goes down to an atmospheric pressure level, the pressure sensor detects the pressure down and the pressure control valve provided between the fuel tank and the canister is automatically closed for a specified time. Therefore, even if a vehicle driver inadvertently forgets to switch the ignition key off at fueling, fuel does not flow out of the canister when the fuel tank is filled up. The system does not need any additional device.

Abstract: A controller for an internal combustion engine including: an introducing path for introducing air or a mixture of fuel and air into an intake manifold of the internal combustion engine; a control valve, arranged along the introducing path, for controlling an amount of the air or the mixture of fuel and air introduced therein; and a pressure sensor for detecting pressure within the introducing path between the control valve and the intake manifold.

Abstract: A fuel-line tube formed wholly of plastic has ends provided with fittings connecting it to the engine and tank and capable of resisting disconnection from the tube and tank when stressed at less than a predetermined pullout force. This tube has an outside diameter of less than 15 mm and is formed with a corrugated crash-resistant section of a predetermined length which is a maximum of 50% of a precorrugated length and capable of elongation in response to a crash with a tensile force smaller than the pullout force.

Abstract: A test routine for a throttle-valve displacement device is accomplished by use of a potentiometer (6) associated with a setting drive (3) and a potentiometer (5) associated with the throttle valve (1) to determine if the valve is operating properly. If it is found from a comparison of the potentiometer signals that the throttle valve (1) is connected to the gas pedal (2), then the setting drive is moved at specific time intervals at least once in closing direction and then back into the starting, position, and it is tested whether the throttle valve (1) follows the setting device. If so, then there is an erroneous indication of one of the two potentiometers and safety measures can be taken.

Abstract: An on-board diagnostic system for an evaporative emission control system of an internal combustion engine powered vehicle employs a positive displacement reciprocating pump to create in evaporative emission space a pressure that differs significantly from ambient atmospheric pressure. The pump is powered by using engine intake manifold vacuum to force an intake stroke during which both an internal spring is increasingly compressed and a charge of ambient atmospheric air is created in an air pumping chamber space. Vacuum is then removed, and the spring relaxes to force a compression stroke wherein a portion of the air charge is forced into the evaporative emission space. The rate at which the pump reciprocates to alternately execute intake and compression strokes indicates the pressure and flow through a leak in the evaporative emission space. Detection of this rate serves as a measurement of leakage for the purpose of distinguishing integrity of the evaporative emission space from non-integrity.

Abstract: A method for checking the operability of a tank-venting system in a vehicle having an internal combustion engine, which tank-venting system has a tank with a tank-pressure sensor, an adsorption filter connected to the tank via a tank-connecting line, and a tank-venting valve which is connected to the adsorption filter via a valve line, in which system the adsorption filter has a venting line which can be closed with the aid of a shut-off valve, has the following steps:closing the shut-off valve;opening the tank-venting valve;determining the build-up gradient (p+) of the underpressure building up in the tank;closing the tank-venting valve;determining the decay gradient (p-) of the decaying underpressure in the tank;mathematically combining the build-up and decay gradients in a manner such that the influence of the fill level has as little effect as possible on the evaluation variable (Q) formed by means of the combination; and,comparing the value of the evaluation variable with a threshold value (Q.sub.

Abstract: The present invention provides a diagnostic system for an internal combustion engine which detects abnormalities of input/output objects used in controlling operation of the engine when the engine is in respective predetermined operating conditions, and carries out respective predetermined fail-safe actions when abnormalities of the input/output are detected. When an abnormality of the input/output objects was detected on the last occasion and has also been detected on the present occasion, and at the same time it is determined that a change in the operating environment of the engine has occurred between when the abnormality was detected on the last occasion and when it has been determined on the present occasion, occurrence of the abnormality is finally determined.

Abstract: The invention is directed to a method for checking the tightness of a tank-venting system when a pregiven test condition is satisfied. The method includes the steps of: (a) building up a difference pressure in the tank-venting system irrespective of whether the pregiven test condition is satisfied; (b) determining the presence of the test condition and then closing the tank-venting system; (c) determining the value of the decay gradient of the difference pressure when the pregiven test condition is satisfied thereby losing no time in starting the check of the tightness; and, (d) drawing a conclusion as to the tightness of the tank-venting system when the value of the decay gradient is less in magnitude than a threshold decay gradient. In this way, as soon as the test condition is satisfied, a determination of the value of the decay gradient of the difference pressure already built up can be started. An apparatus for carrying out the method is also disclosed.

Abstract: An evaporative fuel-processing system for an internal combustion engine includes an evaporative emission control system having a fuel tank, a canister, a passage extending from the canister to an intake passage of the engine, and a purge control valve arranged across the passage, and a pressurization device for pressurizing the interior of the evaporative emission control system. An ECU actuates the pressurization device to bring the evaporative emission control system into a positively pressurized state, after the purge control valve and an open-to-atmosphere control valve arranged across a passage connected to the canister are closed, and detects an amount of evaporative fuel generated in the fuel tank. The ECU determines whether or not a leakage occurs from the evaporative emission control system, based on a rate of variation in pressure within the evaporative emission control system, and a reference value which is determined based on the amount of evaporative fuel detected.

Abstract: A leak diagnosis system is provided for diagnosing a leak condition of an evaporative emission control system for an internal combustion engine. The leak diagnosis system receives a signal indicative of a pressure in the evaporative emission system and obtains a converged limit negative pressure in the evaporative emission control system when the evaporative emission control system is communicated with the operating engine. The leak diagnosis system diagnoses a leak condition by comparing the converged limit negative pressure with a leak decision value.

Abstract: A dynamic wastegate failure detection apparatus for determining wastegate failure levels for individual internal combustion engines is disclosed. The apparatus repeatedly measures and stores intake boost pressures at times when the engine is producing higher boost pressure levels. The apparatus calculates a boost pressure limit value as a function of the stored boost pressures. A wastegate failure is indicated and the engine output power is derated when a boost pressure value exceeds the sum of the boost pressure limit value and a predetermined pressure differential.

Abstract: An evaporative emission control system for an internal combustion engine detects abnormality of the system based on pressure within a purging passage at a location between a purge control valve arranged therein and an intake passage of the engine, and pressure within a canister for adsorbing evaporative fuel generated from a fuel tank of the engine, when it delivers a valve opening command to open the purge control valve.

Abstract: An improved evaporative fuel-purging control system for controlling a purging flow rate which is controlled by a solenoid purge control valve regulated with a pulse waveform signal. As for the characteristic of the purge control valve, differing periods of the signal differentiates the control valve linearity of purging flow rate with respect to the signal duty ratio. To improve the linearity, the pulse waveform signal period which creates the substantial linearity is selected among preset periods periods according to the preset duty ratio which works as a threshold value.