6.6. Control system of the VG33E engine. Procedures of diagnostics
Due to use of the high-speed electronic computer (processor) the control system of the engine carries out coordination of such vital processes as configuration of air-fuel mix, installation and continuous adjustment of a corner of an advancing of ignition, functioning of systems of recirculation of the fulfilled gases and stabilization of turns of idling and so forth. The task of receiving the maximum return from the engine in any road conditions at the minimum fuel consumption and concentration of maintenance of toxic components in the fulfilled gases is at the center set.
Function chart of a control system of the VG33E engine
Location of the relay of ignition
Location of the relay of the fuel pump
The chart of gleams of a control lamp of MIL at delivery of diagnostic codes
The task of increase in efficiency of return of the engine and ensuring the maximum comfort of movement set for system is carried out by tracking and adjustment of the following parameters:
- Corner of an advancing of ignition and time of an overshoot of inlet and final valves in relation to provisions of pistons;
- Composition of the air-fuel mix given to combustion chambers in each working step of pistons;
- The moment of ignition of the air-fuel mix compressed in the cylinder at the end of a step of compression;
- Temperature of combustion of gas mixture in cylinders, especially during the operation of the engine under loading;
- Engine turns in any operating conditions.
All listed parameters are controlled and corrected by an electronic control system of the engine, providing its maximum return at the minimum fuel consumption and issue in the atmosphere of toxic products of combustion practically under any service conditions of the car.
Quality management of air-fuel mix
For ensuring operation of the petrol engine on single turns in combustion chambers the gas mixture enriched with fuel has to move. At the movement of the car with a cruiser speed the quantity of an air component in mix increases (impoverishment). Increase in load of the engine, work of the last on high turns is also followed by enrichment of air-fuel mix. Any changes of quality of mix have to be made smoothly, whenever possible, imperceptibly for the driver. The electronic control system of the Infiniti engine provides precision management of amount of the fuel injected into the engine on the basis of information on amount of the air which is soaked up in the engine arriving from the corresponding sensors of the analysis, turns of a bent shaft and the provision of a pedal of gas / a butterfly valve.
Measurement of a mass consumption of the atmospheric air coming to the engine is carried out built in to the inlet air highway of the sensor of measurement of mass of air (MAF). Sensors of this type are capable to monitor the slightest changes of an expense and density of an air stream and possess very small lag effect, almost instantly correcting parameters of the information signal given on ECM. On the basis of the analysis of parameters of the impulses of tension of ECM arriving from the MAF sensor develops the command for the corresponding correction of amount of the fuel injected into the engine by the thinnest adjustments of duration of time of opening of needle valves of injectors. As the range of changes makes milliseconds, working parameters of the engine are corrected smoothly, without throws and failures of turns.
System of the consecutive distributed fuel injection
On the Infiniti models considered in the present manual the distributed system of injection when each of combustion chambers is equipped with the individual, placed in inlet port injector is used. Injectors provide fine dispersion of fuel, under the pressure of injected directly into a stream of the air stream given to inlet port of the combustion chamber. As the moments of injection are coordinated with an ignition order, it is about system of consecutive type. The injection of accurately dosed amount of fuel is made just before the moment of opening of the inlet valve of each of cylinders.
Functioning of injectors is defined by supply of fuel which pressure in a path of a power supply system is corrected depending on depression depth in the inlet pipeline. The fuel given under pressure is pumped over via the filter of thin cleaning installed in a motive compartment and comes to the fuel highway with the injectors which are built in in it. Thus, on an entrance of injectors excessive pressure is constantly supported that guarantees uninterrupted operation of injection at any moment when opening needle valves.
Due to excess fuel redirection back in the fuel tank the special regulator of pressure of fuel provides on an entrance of injectors constant superfluous over pressure in the inlet pipeline a pressure of 2.4 kgfs/cm 2 (235 kPa).
Such scheme allows ECM to carry out adjustment of amount of the fuel injected into combustion chambers simple change of duration of time of opening of injectors — what longer needle valves of injectors remain open, especially the enriched mix moves in cylinders.
Management of an ignition advancing corner
The greatest efficiency gives the chance of dynamic management of ignition when the moment of ignition of air-fuel mix is corrected depending on specific conditions of functioning of the engine. Load of the engine, frequency of rotation of a bent shaft, temperature of cooling liquid, atmospheric pressure (height above sea level) and so forth can act as the operating parameters. Receives all necessary data of ECM from the corresponding information sensors.
On the Infiniti QX4 models the electronic system of ignition with the distributor is used. Basic elements of the distributor are the provisions of the camshaft (CMP) which are built in it the optical sensor on a light-emitting diode (LED), the powerful transistor and the coil of ignition (see the illustration Ignition Distributor Design).
The CMP sensor traces turns of the engine and delivers to ECM information on position of pistons.
The powerful transistor on signals of ECM makes activation of the coil of ignition with delivery in the fullness of time to tension VV on the corresponding spark plug. Food is given for the coil via the relay (see the illustration Location of the Relay of Ignition) from the ignition switch.
At emergence in combustion chambers of a detonation of air-fuel mix the increased level of vibrations is caught by the sensor of detonations (KS) and will be transformed to information signals on the basis of which analysis ECM makes the corresponding shift of a corner of an advancing of ignition towards lag for the purpose of elimination of detonation process.
Management of combustion temperature
The nitrogen oxides which are formed in products of combustion of air-fuel mix at temperatures of burning over 1093 °C are among the most typical photochemical pollutants of the atmosphere. The most obvious of ways of fight for reduction of issue of NOH is decrease in working temperature in combustion chambers. These objectives are achieved due to branch to the inlet highway of a small amount of the inert fulfilled gases, the corresponding process received the name of process of admixture of the fulfilled gases (EGR).
System of stabilization of turns of idling
Set of various factors exert impact on quantity of turns of idling. So, for example, the cold engine tends to violation of stability of turns as idling, and under loading. Turning on of such auxiliary units as the K/V compressor, the steering pump, etc. inevitably leads to decrease in turns of idling. Activation of such power-intensive equipment as head headlights leads heaters of glasses, fans of the cooling system to increase in load of the engine. For the purpose of stabilization of turns of idling and ensuring the maximum economy of fuel consumption in any service conditions the control system of the engine provides automatic control of turns of idling. On the basis of the analysis of the data of ECM arriving from the corresponding information sensors calculates optimum value of turns of idling and exercises control of amount of the air given to the inlet pipeline by means of the valve of the additional IACV-AAC air regulating. As the amount of the air which is soaked up in the engine is defined on the basis of information arriving from the MAF, ECM sensor always has a possibility of the corresponding adjustment of duration of opening of injectors for the purpose of configuration of air-fuel mix of the required structure.
System of onboard diagnostics OBD-II
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The material given below has only descriptive character and is not attached to any concrete brand or model of the car. |
Data on diagnostic units
Use of the digital measuring instrument is preferable for several reasons. First, on analog devices it is rather difficult (sometimes, it is impossible), to define result of the indication to within the 100-th and thousand shares while at inspection of the contours including electronic components in the structure, such accuracy is of particular importance. The second, not less important, the fact that the internal contour of a digital multimeter, has rather high impedance is the reason (internal resistance of the device makes 10 million Ohms). As the voltmeter is connected to the checked chain in parallel, the accuracy of measurement of subjects is higher, than smaller parasitic current will pass through actually device. This factor is not essential at measurement of rather high values of tension (9 — 12 V), however becomes defining at diagnostics of the elements giving low-voltage signals, such as, for example, lambda probe where it is about measurement of shares of volt.
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The most convenient devices for diagnostics of control systems of the engine of modern models of cars are manual readers of skanerny type. |
Scanners of the first generation serve for reading of codes of malfunctions of the OBD-I systems. Before application the reader should be checked for compliance of model and year of release of the checked car. Some scanners are multipurpose at the expense of a possibility of change of a cartridge depending on model of the diagnosed car (Ford, GM, Chrysler, etc.), others are tied to requirements of the regional authorities and intended for use in certain regions of the world (Europe, Asia, the USA, etc.).
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The diagnostic New Generation Star (NGS) scanner (also the FDS 2000, Bosch FSA 560 [www.bosch.de] and KTS 500 [0 684 400 500] scanners were widely used). |
With introduction to production to meeting requirements of the last legislations for environmental protection of system of onboard diagnostics of the second generation (OBD-II) readers of a special design began to be issued. Some producers marketed the scanners intended for use by amateur mechanics in house conditions — ask in shops of automobile accessories.
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The free version of a browser OBD-II can be downloaded from the website of authors of the present manual arus.spb.ru. |
Reading of the codes of malfunctions which are written down in memory of system of self-diagnostics can be made by means of a control lamp of refusals of MIL.
General description of the OBD system
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At the modules equipped with the OBD-II system on installed under a cowl Schild there has to be a record "OBD-II compliant", and the diagnostic DLC socket has to be 16-contact. As a rule, the OBD-II system surely equips the models intended for the North American market since 1996 of release, and also the European models, since 2000 release. |
Several diagnostic devices making monitoring of separate parameters of systems of decrease in toxicity and fixing the revealed refusals in memory of the onboard processor in the form of individual codes of malfunctions are a part of the OBD system. The system makes also check of sensors and actuation mechanisms, controls operational cycles of the vehicle, provides a possibility of freezing of parameters and cleaning of the block of memory.
All models described in the present manual are equipped with system of onboard diagnostics of the second generation (OBD-II). A basic element of system is the onboard processor more often called by the electronic module of management (ECM). ECM is a brain of a control system of the engine. Basic data arrive on the module from various information sensors and other electronic components (switches, the relay, etc.). On the basis of the analysis of the data arriving from information sensors and according to the basic parameters put in the processor memory, ECM develops commands for operation of various operating relays and actuation mechanisms, carrying out thereby adjustment of working parameters of the engine and providing maximum efficiency of its return at the minimum fuel consumption.
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Data read-out of the processor memory of OBD-II is made by means of the special scanner connected to the 16-contact diagnostic socket of reading of the database (DLC) located at the left under the dashboard. A — the Diagnostic socket of the OBD II system, at connection use the standard OBD-II J1962 cable. Purpose of conclusions — see the scheme Diagnostic sockets
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Reading of the codes of malfunctions which are written down in memory of system of self-diagnostics can be made by means of a control lamp on the control panel. |
Special guarantee certificates with the extended validity extend to service of components of control systems of engine / decrease in toxicity of the fulfilled gases. It is not necessary to make attempts of independent performance of failure diagnostics of ECM or replacement of components of system, to an exit of terms of these obligations — address specialists of company car repair shops of the Infiniti company.
Information sensors (depending on a car complete set)
Oxygen sensors (lambda probes). The sensor develops a signal which amplitude depends on a difference of content of oxygen (O2) in the fulfilled gases of the engine and external air.
Sensor of provision of a bent shaft (ICR). The sensor informs ECM on the provision of a bent shaft and turns of the engine. This information is used by the processor during the determining of the moments of injection of fuel and installation of a corner of an advancing of ignition.
Sensor of position of pistons (CYP). On the basis of the analysis of the signals of ECM arriving from the sensor calculates position of the piston of the first cylinder and uses this information when determining the moments and the sequence of injection of fuel in engine combustion chambers.
BMT (TDC) sensor. The signals developed by the sensor are used by ECM when determining installations of a corner of an advancing of ignition at engine launch.
Sensor of temperature of cooling liquid of the engine (EST). On the basis of information of ESM arriving from the sensor carries out necessary corrections of composition of air-fuel mix and a corner of an advancing of ignition, and also controls work of the EGR system.
The sensor of temperature of the soaked-up air (IAT). ECM uses information arriving from the IAT sensor at corrections of a stream of fuel, installations of a corner of an advancing of ignition and management of functioning of the EGR system.
Sensor of provision of a butterfly valve (TPS). The sensor is located on the case of a throttle and connected to an axis of a butterfly valve. Determines the angle of opening of a butterfly valve (is operated by the driver from the accelerator pedal) by amplitude of the given TPS of a signal of ECM and as appropriate corrects supply of fuel to inlet ports of combustion chambers. The failure of the sensor, or weakening of its fastening leads to interruptions of injection and violations of stability of turns of idling.
The sensor of absolute pressure in the pipeline (MAR). The sensor controls the depression depth variations in the inlet pipeline connected with changes of turns of a bent shaft and load of the engine and will transform the obtained information to an amplitude signal. ECM uses information delivered by the MAR and IAT sensors at thin corrections of supply of fuel.
Sensor of the atmospheric pressure (BARO). The sensor develops the amplitude signal proportional to changes of atmospheric pressure which is used by ECM when determining duration of the moments of injection of fuel. The sensor is built in the ECM module and is not subject to service in an individual order.
Sensor of a detonation (KS). The sensor reacts to change of level of the vibrations connected with detonations in the engine. On the basis of information of ECM arriving from the sensor carries out the corresponding correction of a corner of an advancing of ignition.
Sensor of speed of the movement of the car (VSS). As appears from its name, the sensor informs the processor on the current speed of the movement of the car.
Sensor of size of opening of the EGR valve. The sensor notifies ECM on EGR valve plunger shift size. The obtained information is used then the processor at management of functioning of system of recirculation of the fulfilled gases.
Pressure sensor in the fuel tank. The sensor is a component of system of catching of fuel evaporations (EVAP) and serves for tracking of pressure of vapors of gasoline in a tank. On the basis of information of ECM arriving from the sensor issues commands for operation of electromagnetic valves of a purge of system.
Sensor switch of pressure of system of hydrostrengthening of a wheel (PSP). On the basis of information of ECM arriving from the PSP sensor switch provides increase in turns of idling due to operation of the sensor of system of stabilization of turns of idling (IAC) for the purpose of compensation of the increasing loads of the engine connected with functioning of the steering hydraulic booster at commission of maneuvers.
Transmission sensors. In addition to the data arriving from VSS, ECM obtains also information from the sensors placed in the transmission, or connected to it. Are among such sensors: (a) RPM meter of a secondary (radical) shaft and (b) RPM meter of an intermediate shaft.
Sensor switch of management of inclusion of a clutch coupling of the conditioner of air. When giving power supply from the battery to the electromagnetic valve of the K/V compressor the corresponding information signal arrives on ECM which regards it as the evidence of increase of load of the engine and as appropriate corrects turns of its idling.
Actuation mechanisms
Relay of the fuel pump. ECM makes activation of the relay of the fuel pump when turning the ignition key in situation START or RUN. At inclusion of ignition activation of the relay provides rise in pressure in a power supply system. Location of the relay of the fuel pump on the Infiniti QX4 models — see the illustration Location of the Relay of the Fuel Pump).
Fuel injection injector(s). ECM provides individual inclusion of each of injectors according to an established order of ignition. Besides, the module controls duration of opening of injectors determined by the width of the operating impulse measured in milliseconds and defining amount of the fuel injected into the cylinder. More detailed information on the principle of functioning of system of injection, replacement and service of injectors is provided in the Head of the Feed and control system.
Ignition distributor. The distributor operates functioning of the coil of ignition, defining the required basic advancing on the basis of the developed ECM teams.
Valve of stabilization of turns of idling (IAC). The IAC valve carries out a dosage of amount of the air bypassed bypassing a butterfly valve when the last is closed or holds idling position. ECM operates opening of the valve and formation of the resulting air stream.
Electromagnetic valve of a purge of a coal adsorber. The valve is a component of system of catching of fuel evaporations (EVAP) and, working at the command of ECM, makes production of the fuel vapors which accumulated in an adsorber in the inlet pipeline for the purpose of burning them in the course of normal functioning of the engine.
Electromagnet of management of a purge of a coal adsorber. The electromagnet is used by ECM when checking by the OBD-II system of serviceability of functioning of the EVAP system.
Reading of codes of malfunctions and cleaning of the processor memory
At detection of the malfunction repeating in a row on two trips, ECM issues the command for inclusion of the control lamp which is built in in an instrument guard "Check the engine", called also by the indicator of refusals (MIL). At the same time the monitor switches to emergency operation. The lamp will continue to burn until memory of system of self-diagnostics is not cleared of the codes of the revealed malfunctions brought in it (see below).
Reading of codes by means of the scanner
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Reading of codes of malfunctions is made by connection of the special reader (see above) to the 16-contact diagnostic DLC socket — act according to indications of the menu of the device. The list of codes is provided in Specifications. |
Reading of codes by means of a control lamp of refusals of MIL
Kill the engine and switch off ignition.
At detection of the malfunction repeating in a row on two trips, RSM issues the command for inclusion of the control lamp which is built in in an instrument guard "Check the engine", called also by the indicator of refusals. The lamp will continue to burn until then, violation will not disappear, and will not be shown during three and more trips.
For reading of codes it is necessary to provide access to RSM for the purpose of switching of the selector to highlighting of codes by means of diagnostic lamps / a control lamp "Check the engine". RSM should remove from the basic arm (without disconnecti