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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

Ignition distributor design

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

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.

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.).

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.

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

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.

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

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 disconnecting an electrical wiring) and to work according to the instructions given below.

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

When checking a chain, first of all, disconnect the corresponding electrical wiring 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 the suspected element — if the nominal resistance of an element is small, it is necessary to take such factors as accuracy and internal resistance of the measuring device into account.

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 most often is connected with break of an electrical wiring.

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 the scanner to system and choose the CLEARING CODES function (Removal of codes) in its menu — further follow the instructions highlighted on the device.

The code which is written down in memory is removed automatically if the corresponding malfunction does not appear during 20 following in a row one after another of starts of the engine (the quantity of turns has to be not lower than 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 start of system 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. At the same time the first 15-20 minutes after primary start of the engine before the end of adaptation of ECM, some violation of stability of its turns can take place.

Application of an oscillograph for observation of workers of a control system

General information

Digital multimeters perfectly are suitable for check of the electric chains which are in a static state, and also for fixing of slow changes of the traced parameters. When conducting the dynamic checks which are carried out on the working engine and also at identification of the reasons of sporadic failures the oscillograph becomes absolutely irreplaceable tool.

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 when performing 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 evidence of violation of serviceability of functioning of a control system in general. On the other hand, correctness of a form of the impulses given by the sensor can serve as a reliable guarantee of lack 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 the obtained information can be easily made by elementary visual comparison of the oscillograms removed during check with the temporary dependences typical for various sensors and actuation mechanisms of automobile control systems given below.

Parameters of periodic signals

General information

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

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

Signals of a direct current

The only performance data of such signals is tension.

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

Signals of alternating current

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

Frequency-modulated signals (WC)

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

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

The signals modulated on width of an impulse (ShIM)

Performance data of signals of the pulse-width modulation (PWM) are 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 amplitude, frequency and a form of the sequence of separate impulses.

Signals of this sort 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 there can be schitana the codes of malfunctions which are stored in memory (a code 1223 — see the illustration Chart of Gleams of a Control Lamp of MIL at delivery of diagnostic codes).

Amplitude and form of a signal remain constants, the written-down value will be given until memory of the module is not cleared.

Interpretation of oscillograms

Tension

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

In chains of alternating current signal amplitude already unambiguously depends on the frequency of operation of a source of a signal, so, amplitude of the signal given by the sensor of provision of a bent shaft (CKP) will increase with increase in turns of the engine.

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

Frequency

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

The form of the 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 the scale of temporary development of an oscillograph.

In certain cases the oscillogram of a signal turns out rather reference dependence developed specularly what is explained by reversibility of polarity of connection of the corresponding element and, in the absence of the 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 with only two alarm wires together with a set of the various probes allowing to carry out connection of the device 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 grounded point (weight).

Injection injectors

Control of composition of air-fuel mix in modern automobile electronic systems of injection of fuel is exercised by timely adjustment 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 the 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 visual observation of changes of a form of the operating signal at a variation of working parameters of the engine. So, duration of impulses at an engine provorachivaniye on single turns has to be slightly higher, than during the operation of the unit on low turns. Increase in turns of the engine has to be followed by corresponding increase in time of stay of injectors abroach. This dependence is especially well shown when opening a butterfly valve by short pressing the accelerator pedal.

Bystry closing of a butterfly valve has to lead to the oscillogram flattening confirming the fact of an overshoot of injectors (for systems with fuel supply trim).

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

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

Typical dependence of duration of the operating impulses of opening of injectors on the working condition of the engine is presented in the table given below.

Inductive sensors

Electromagnetic valve of stabilization of turns of idling (IAC)

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

The common distinctive feature of all valves is the fact that porosity of a signal has to decrease with increase of the load of the engine connected with inclusion of the additional consumers of power causing decrease in 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 the given ECM of a command signal.

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

Step electric motor, reacting to the given ECM the pulsing operating signal, makes step correction of turns of idling of the engine according to the working temperature of cooling liquid and the current load of the engine.

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

Lambda probe (oxygen sensor)

Sensor of a detonation (KS)

Ignition signal at the exit of the amplifier

Primary winding of the coil of ignition