6-6-sistema-upravleniya-dvigatelem-vg33e-procedury-diagnostiki.html

6.6. Control system of the VG33E engine. Diagnostics procedures

At the expense of use of the high-speed electronic computer (processor) the control system of the engine carries out coordination of such vital processes, as configuration of an air and fuel mix, installation and continuous adjustment of a corner of an advancing of ignition, functioning of systems of a retsirkulyatsiya of the fulfilled gases and stabilization of turns of idling and so forth. At the center an objective of receiving the maximum return from the engine in any road conditions at minimum fuel consumption and concentration of the maintenance of toxic components in the fulfilled gases.

Function chart of a control system of the VG33E engine

Design of the distributor of ignition

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 put before system of increase of efficiency of return of the engine and ensuring the maximum comfort of movement is carried out by tracking and adjustment of the following parameters:

• Corner of an advancing of ignition and time of a perekryvaniye of inlet and final valves in relation to positions of pistons;
• Structure of the air and fuel mix submitted to chambers of combustion in each working step of pistons;
• The moment of ignition compressed in the cylinder at the end of a step of compression of an air and fuel mix;
• Temperature of combustion of gas mixture in cylinders, especially at operation of the engine under loading;
• Engine turns in any operating conditions.

All transferred parameters are supervised and corrected by an electronic control system of the engine, providing its maximum return at minimum fuel consumption and issue in the atmosphere of toxic products of combustion practically under any service conditions of the car.

Quality management of an air and fuel mix

For ensuring operation of the petrol engine on single turns in chambers of combustion the gas mixture enriched with fuel should move. At car movement with cruiser speed the quantity of an air component in a mix increases (pauperization). Increase of load of the engine, work of the last on high turns also is accompanied by enrichment of an air and fuel mix. Any changes of quality of a mix should be made smoothly, whenever possible, is imperceptible for the driver. The electronic control system of the Infiniti engine provides precision management of amount of fuel injected into the engine on the basis of arriving from the corresponding sensors of the analysis of information on amount of air soaked up in the engine, turns of a cranked shaft and the provision of a pedal of a gas / butterfly valve.

Measurement of a mass consumption of atmospheric air arriving in the engine is carried out built in to the inlet air highway of the sensor of measurement of weight of air (MAF). Sensors of this type are capable to trace the slightest changes of an expense and density of an air stream and possess very small lag effect, almost instantly correcting parameters of information signal given out on ECM. On the basis of the analysis of parameters of impulses of tension of ECM arriving from the MAF sensor develops command for the corresponding correction of amount of fuel injected into the engine by the thinnest corrections 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 injection of fuel

On the Infiniti models considered in the real Management the distributed system of injection when each of chambers of combustion is equipped with the individual injector placed in inlet port is used. Injectors provide tonkodispersny dispersion of fuel, under the pressure of injected directly in a stream submitted to inlet port of the chamber of combustion of an air stream. As the moments of injection are coordinated with ignition order, it is a question of system of consecutive type. Injection of accurately dosed out amount of fuel is carried out directly ahead of the moment of opening of the inlet valve of each of cylinders.

Functioning of injectors is defined by supply of the fuel which pressure in a path of a power supply system is corrected depending on depth of depression in the inlet pipeline. Fuel submitted under pressure is pumped over via the filter of thin cleaning established in an impellent compartment and arrives to the fuel highway with the injectors built in in it. Thus, on an entrance of injectors superfluous pressure that guarantees uninterrupted operation of injection at any moment when opening needle valves is constantly supported.

At the expense of the redirection of excess of fuel back in a 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 in size in 2.4 kgfs/cm ² (235 kPas).

Such scheme allows ECM to carry out adjustment of number of combustion of fuel injected into chambers by simple change of duration of time of opening of injectors — than more long needle valves of injectors remain open, especially the enriched mix moves in cylinders.

Management of a corner of an advancing of ignition

The greatest efficiency gives the chance dynamic management of ignition when the moment of ignition of an air and fuel mix is corrected depending on specific conditions of functioning of the engine. As operating parameters load of the engine, frequency of rotation of a cranked shaft, temperature of cooling liquid, atmospheric pressure (height above sea level) and so forth can act. All necessary data of ECM receives 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 built in it the optical sensor of provision of a camshaft (CMP) on a light-emitting diode (LED), the powerful transistor and the ignition coil (see an illustration the Design of the distributor of ignition).

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 tension VV on the corresponding spark plug. A food on the coil stands out via the relay (see an illustration Location of the relay of ignition) from the ignition switch.

At emergence in chambers of combustion of a detonation of an air and fuel mix the raised level of vibrations is caught by the sensor of detonations (KS) and will be transformed to information signals on the basis of which analysis of ECM makes the corresponding shift of a corner of an advancing of ignition towards backlog for the purpose of elimination of detonation process.

In combustion management in temperature

The oxides of nitrogen which are forming in products of combustion of an air and fuel mix at temperatures of burning from above 1093°С belong to number of the most typical photochemical pollutants of the atmosphere. Most obvious of ways of fight for reduction of issue of NOH is decrease in working temperature in combustion chambers. This purpose is reached at the expense of branch to the inlet highway of a small amount of the inert fulfilled gases, the corresponding process received the name of process of a podmeshivaniye of the fulfilled gases (EGR).

System of stabilization of turns of idling

Quantity of turns of idling influence a set of various factors. 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 To/in compressor, the steering pump, etc. inevitably leads to decrease in turns of idling. Activation of such power-intensive equipment as head headlights heaters of glasses, fans of system of cooling conducts to increase in loading at 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 data of ECM arriving from the corresponding information sensors calculates optimum value of turns of idling and exercises administration of amount of air submitted to the inlet pipeline by means of the valve of the additional IACV-AAC air regulating. As the amount of air soaked up in the engine is defined on the basis of information arriving from the sensor MAF, ECM always has possibility of the corresponding correction of duration of opening of injectors for the purpose of configuration of an air and fuel mix of demanded structure.

System of onboard diagnostics of OBD-II

Data on diagnostic devices

Use of a digital measuring instrument preferably 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 in the structure electronic components, such accuracy takes on special significance. The second, the reason that fact is not less important that the internal contour of a digital multimeter, has rather high impedance (internal resistance of the device makes 10 million Ohm). As the voltmeter is connected to a checked chain in parallel, accuracy of measurement by that is higher, than the smaller parasitic current will pass through actually device. This factor is not essential at measurement of rather high values of tension (9 — 12 In), however there is defining at diagnostics of elements giving out low-voltage signals, such, as, for example, a lambda probe where it is a question of measurement of shares of volt.

Scanners of the first generation serve for reading of codes of malfunctions of OBD-I systems. Before application the input reader should be checked on compliance of model and year of release of the checked car. Some scanners are multipurpose at the expense of possibility of change of a cartridge depending on model of the diagnosed car (Ford, GM, Chrysler, etc.), others are adhered to requirements of the regional authorities and are intended for use in certain regions of the world (Europe, Asia, the USA etc.).

With introduction in production meeting the requirements of the last legislations on environmental protection of system of onboard diagnostics of the second generation (OBD-II) input readers of a special design started to be issued. Some producers adjusted release of the scanners intended for use by amateur mechanics in house conditions — ask in shops of automobile accessories.

Reading written down in memory of system of self-diagnostics of codes of malfunctions can be made by means of a control lamp of refusals of MIL.

General description of OBD system

The structure of OBD system includes some diagnostic devices making monitoring of separate parameters of systems of decrease in toxicity and fixing revealed refusals in memory of the onboard processor in the form of individual codes of malfunctions. The system makes also check of sensors and actuation mechanisms, supervises operational cycles of a vehicle, provides possibility of freezing of parameters and cleaning of the block of memory.

All models described in the real Management 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 data arriving from information sensors and according to put in memory of the processor in base parameters, 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.

On service of components of control systems of engine / decrease in toxicity of the fulfilled gases special guarantee certificates with the prolonged validity period extend. It is not necessary to undertake attempts of independent performance of problem diagnostics of ECM or replacement of components of system, to an exit of terms of these obligations — address to specialists of firm 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 the content of oxygen (О2) in the fulfilled gases of the engine and external air.

Sensor of provision of a cranked shaft (SKR). The sensor informs ECM on the provision of a cranked shaft and engine turns. This information is used by the processor at definition 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 signals of ECM arriving from the sensor calculates position of the piston of the first cylinder and uses this information at definition of the moments and sequence of injection of fuel in chambers of combustion of the engine.

(TDC) VMT sensor. Signals developed by the sensor are used by ECM at definition of installations of a corner of an advancing of ignition at the moment of engine start.

The sensor of temperature of cooling liquid of the engine (eats). On the basis of information of ESM arriving from the sensor carries out necessary corrections of structure of an air and fuel mix and a corner of an advancing of ignition, and also supervises EGR system work.

The sensor of temperature of 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 EGR system functioning.

Sensor of provision of a butterfly valve (TPS). The sensor is located on the case of a throttle and connected to a butterfly valve axis. By amplitude of given-out TPS of a signal of ECM determines a corner of opening of a butterfly valve (copes the driver from a gas pedal) and as appropriate corrects supply of fuel to inlet ports of chambers of combustion. 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 supervises variations of depth of depression in the inlet pipeline, connected with changes of turns of a cranked shaft and load of the engine and will transform received information to a peak signal. ECM uses information delivered by MAR and IAT sensors at thin corrections of supply of fuel.

Sensor of atmospheric pressure (BARO). The sensor develops the peak signal proportional to changes of atmospheric pressure which is used by ECM at determination of duration of the moments of injection of fuel. The sensor is built in the ECM module and to service in an individual order is not subject.

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 movement of the car (VSS). As appears from its name, the sensor informs the processor on the current speed of movement of the car.

Sensor of size of opening of the EGR valve. The sensor notifies ECM on size of shift of a plunzher of the EGR valve. Received information is used then the processor at management of functioning of system of a retsirkulyatsiya of the fulfilled gases.

The pressure sensor in a fuel tank. The sensor is a component of system of catching of fuel evaporations (EVAP) and serves for pressure tracking паров gasoline in a tank. On the basis of information of ECM arriving from the sensor gives out 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 of turns of idling at the expense of operation of the sensor of system of stabilization of turns of idling (IAC) for the purpose of compensation of 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 receives also information from sensors placed in a transmission, or connected to it. Number of such sensors treat: (а) sensor of turns of a secondary (radical) shaft and (b) sensor of turns of an intermediate shaft.

Sensor switch of management of turning on of the coupling of coupling of the conditioner of air. When giving food from the battery to the electromagnetic valve of the To/in compressor the corresponding information signal arrives on ECM which regards it as the certificate 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 at an ignition key povorachivaniye in the situation START or RUN. At ignition inclusion activation of the relay provides pressure lifting in a power supply system. Location of the relay of the fuel pump on the Infiniti QX4 models — see an illustration Location of the relay of the fuel pump).

Injector (ы) fuel injection. ECM provides individual inclusion of each of injectors according to an ignition established order. Besides, the module supervises duration of opening of the injectors, defined in the width of an operating impulse measured in milliseconds and defining amount of fuel injected into the cylinder. More detailed information on a principle of functioning of system of injection, replacement and service of injectors is provided in Head of the Power supply system and management.

Ignition distributor. The distributor operates functioning of the coil of ignition, defining a demanded base advancing on the basis of developed ECM teams.

Valve of stabilization of turns of idling (IAC). The IAC valve carries out a dosage of amount of the air which is restarted up bypassing a butterfly valve when the last is closed, or occupies the provision of idling. Opening of the valve and formation of a rezultiruyushchy air stream ECM operates.

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, carries out release accumulated in an adsorber паров fuels 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 at check by OBD-II system of serviceability of functioning of EVAP system.

Reading of codes of malfunctions and cleaning of memory of the processor

At detection of the malfunction repeating in a row on two trips, ECM gives out command for inclusion of the control lamp built in in an instrument guard «Check the engine», called also the indicator of refusals (MIL). At the same time the monitor is switched to emergency operation. The lamp will continue to burn until memory of system of self-diagnostics will not be cleared of the codes of the revealed malfunctions brought in it (see below).

Reading of codes by means of the scanner

Reading of codes by means of a control lamp of refusals of MIL

Muffle the engine and switch off ignition.

At detection of the malfunction repeating in a row on two trips, RSM gives out command for inclusion of the control lamp built in in an instrument guard «Check the engine», called also 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 selector switching on highlighting of codes by means of diagnostic lamps / a control lamp «Check the engine». RSM should be removed from the basic arm (without disconnecting electroconducting) and to operate according to the instructions provided below.

The highlighted code allows to define only the system chain which refusal was fixed by self-diagnostics system. So, if the code indicates malfunction of the sensor of temperature of cooling liquid (ECT), the probability of violation of functioning actually the management module is not excluded also. To establish truth it is possible or sensor replacement, or by carrying out the corresponding control measurements.

At chain check, first of all, disconnect the corresponding electroconducting and check a condition of its contact connections of connection. In case of need smooth out plugs, having completely removed from them oxidation traces.

Check reliability of fastening of a cable at a cable tip.

Check resistance of a suspected element — if nominal resistance of an element is insignificant, it is necessary to take into consideration such factors, as accuracy and internal resistance of the measuring device.

Check integrity of the wires going to the module of management (be in case of need verified with schemes of electric connections).

When reading the codes indicating excessive understating of level of a signal, first of all, it is necessary to make sure of reliability of grounding of the corresponding component. Overestimate of level of a signal appears connected with electroconducting break more often.

Information contents of categories of a 5-digit code of a type of P0380

Cleaning of memory of OBD II

For cleaning of memory of ESM switch off ignition, and disconnect the battery plug not less than for 60 seconds, or connect to system the scanner and choose in its menu the CLEARING CODES function (Removal of codes) — further follow instructions highlighted on the device.

The code written down in memory is removed automatically if the corresponding malfunction does not appear during 20 following in a row one after another engine starts (quantity of turns should be not lower 450 in a minute).

Track, that memory of system was cleared before installation on the engine of new components of systems of decrease in toxicity of the fulfilled gases. If before system start after replacement of the failed information sensor not to make cleaning of memory of refusals, ECM will bring in it a new code of malfunction. Cleaning of memory allows the processor to make change-over on new parameters. Thus the first 15-20 minutes after primary start of the engine before the completion of adaptation of ECM, some violation of stability of its turns can take place.

Oscillograph application for supervision of workers of a control system

General information

Digital multimeters perfectly are suitable for check of the electric chains being in a static condition, and also for fixing of slow changes of traced parameters. At carrying out the dynamic checks which are carried out on the working engine, and also at identification of the reasons of sporadic failures by absolutely irreplaceable tool there is an oscillograph.

Some oscillographs allow to keep oscillograms in the built-in module of memory with the subsequent conclusion of results to the press or their transfer to the carrier of the personal computer already in stationary conditions.

The oscillograph allows to observe periodic signals and to measure tension, frequency, width (duration) of rectangular impulses, and also levels of slowly changing tension. The oscillograph can be used at performance of the following procedures:

• Identifications of failures of unstable character;
• Checks of results of the made corrections;
• Activity monitoring a lambda probe of a control system of the engine equipped with the catalytic converter;
• The analysis of the signals developed a lambda probe, which deviation of parameters from norm is unconditional the certificate of violation of serviceability of functioning of a control system as a whole. On the other hand, correctness of a form of impulses given out by the sensor can serve as a reliable guarantee of absence of violations in a control system.

Reliability and simplicity of operation of modern oscillographs do not demand any special special knowledge and experience from the operator. Interpretation of received information can be easily made by a way of elementary visual comparison of the oscillograms removed during check with the temporary dependences given below typical for various sensors and actuation mechanisms of automobile control systems.

Parameters of periodic signals

General information

• Amplitude: A difference of the maximum and minimum tension (In) a signal within the period;
• Period: Duration of a cycle of a signal (ms);
• Frequency: Quantity of cycles in a second (Hz);
• Width: Duration of a rectangular impulse (ms, microsec);
• Porosity: The relation of the period of repetition to width (In foreign terminology return is applied porosity parameter called by the running cycle, expressed in %);
• Signal form: Sequence of rectangular impulses, individual emissions, sinusoid, sawtooth impulses, etc.

Usually characteristics of the faulty device strongly differ from reference that allows the skilled operator easily and quickly to reveal the refused component by the analysis of the corresponding oscillogram.

Signals of a direct current

The unique performance data of such signals is tension.

Signals of a direct current are developed by the devices presented below:

Signals of an alternating current

The main characteristics of these signals are the amplitude, frequency and a signal form.

The frequency modulated signals (WC)

Performance data of the frequency modulated signals are the amplitude, frequency, a form of a signal and width of periodic impulses.

Sources of a WC of signals are the devices presented below.

The signals modulated on width of an impulse (ShIM)

Performance data of signals of pulse-width modulation (ShIM) are the amplitude, frequency, a form of a signal and porosity of periodic impulses.

Sources of signals of ShIM are the devices presented further.

The coded sequence of rectangular impulses

Performance data are the amplitude, frequency and a form of sequence of separate impulses.

This sort of signals are generated by the module of memory of self-diagnostics of ECM of a control system of the engine.

By the analysis of width and a form of impulses, and also calculation of their quantity in each of groups can be считаны the codes which were stored in memory of malfunctions (a code 1223 — see an illustration the Chart of gleams of a control lamp of MIL at delivery of diagnostic codes).

The amplitude and form of a signal remain the constants, the written-down value will stand out until memory of the module will not be cleared.

Interpretation of oscillograms

Tension

In chains of a direct current level of a signal is limited to supply voltage. As an example it is possible to give a chain of system of stabilization of turns of the idling (IAC) which alarm tension does not change in any way with change of turns of the engine.

In chains of an alternating current the amplitude of a signal already unequivocally depends on frequency of operation of a source of a signal, so, the amplitude of the signal which is given out by the sensor of provision of a cranked shaft (CKP) will increase with increase of turns of the engine.

In a look told if the amplitude of a signal removed by means of an oscillograph appears excessively low or high (up to trimming of top levels), it is enough to switch only a working range of the device, having passed to the corresponding scale of measurement.

Frequency

Frequency of repetition of alarm impulses depends on working frequency of a source of signals.

The form of a removed signal can be edited and brought to a look convenient for the analysis by switching on an oscillograph of scale of temporary development of the image.

As it was already told above, for reduction of a signal to a legible look it is enough to switch scale of temporary development of an oscillograph.

In certain cases the oscillogram of a signal appears rather reference dependence developed specularly that speaks a reversivnost of polarity of connection of the corresponding element and, in the absence of a ban on change of polarity of connection, can be ignored in the analysis.

Typical signals of components of control systems of the engine

Modern oscillographs are usually equipped only with two alarm wires together with a set various щупов, allowing to carry out device connection practically to any device.

The red wire is connected to a positive pole of an oscillograph and is usually connected to the plug of the electronic module of management (ECM). The black wire should be connected to reliably earthed point (weight).

Injection injectors

Management of structure of an air and fuel mix in modern automobile electronic systems of injection of fuel is carried out by timely correction of duration of opening of electromagnetic valves of injectors.

Often on the oscillogram it is possible to observe also a series of the short pulsations following directly an initiating negative rectangular impulse and supporting the electromagnetic valve of an injector abroach, and also the sharp positive throw of tension accompanying the moment of closing of the valve.

Serviceability of functioning of ECM can be easily checked by means of an oscillograph by a way of visual supervision of changes of a form of an operating signal at a variation of working parameters of the engine. So, duration of impulses at an engine provorachivaniye on single turns should be slightly higher, than at operation of the unit on low turns. Increase of turns of the engine should be accompanied by respective increase in time of stay of injectors abroach. This dependence is especially well shown when opening butterfly valve by short pressing a gas pedal.

Fast closing of a butterfly valve should lead to the flattening of the oscillogram confirming the fact of a perekryvaniye of injectors (for systems with an otsekaniye of supply of fuel).

At cold start the engine needs some enrichment of an air and fuel mix that is provided with automatic increase in duration of opening of injectors. In process of warming up duration of operating impulses on the oscillogram should be reduced continuously, gradually coming nearer to value typical for single turns.

In injection systems in which the injector of cold start is not applied, at cold start of the engine the additional operating impulses which are showing on the oscillogram in the form of pulsations of variable length are used.

In the table provided below typical dependence of duration of operating impulses of opening of injectors on a working condition of the engine is presented.

Inductive sensors

Electromagnetic valve of stabilization of turns of idling (IAC)

In automotive industry electromagnetic IAC valves of a set of the various types which are giving out signals of also various form are used.

The common distinctive feature of all valves is that fact that porosity of a signal should decrease with increase of load of the engine, connected with inclusion of additional consumers of the capacity causing fall of turns of idling.

If porosity of the oscillogram changes with increase in loading, however at inclusion of consumers violation of stability of turns of idling takes place, check a condition of a chain of the electromagnetic valve, and also correctness of given-out ECM of a command signal.

Usually in chains of stabilization of turns of idling the 4-polar step-by-step electric motor which description is provided below is used. Check of 2-contact and 3-contact IAC valves is made in a similar manner, however oscillograms of alarm tension given out by them are absolutely unlike.

The step-by-step electromotor, reacting to given-out ECM a pulsing operating signal, makes step correction of turns of idling of the engine according to working temperature of cooling liquid and the current load of the engine.

Levels of operating signals can be checked by means of an oscillograph, measuring щуп which is connected serially to each of four plugs of the step-by-step motor.

Lambda probe (the oxygen sensor)

Sensor of a detonation (KS)

Ignition signal on an exit of the amplifier

Primary winding of the coil of ignition