2.2.1.5. Diagnosing of a control system and engine

Diagnostics of an electronic control system of the engine with injection of gasoline demands observance of an order of its carrying out. Successfully to carry out diagnostics of malfunctions, it is necessary to understand the principles of its work and to distinguish working order from faulty. Existence of necessary diagnostic means, reference books and special training are very important.
Operability of a control system of the engine and systems of injection depends on serviceability of mechanical and hydromechanical systems. Some deviations can be mistakenly taken for malfunctions of an electronic part of a control system:
– low compression;
– the deviation of phases of gas distribution caused by the wrong assembly of knots of the engine after repair;
– an air suction in the inlet pipeline through connections;
– bad quality of fuel.

Precautionary measures
During the work with automobile electronic systems it is necessary to observe requirements for connection, dismantle, assembly, diagnostics of elements of system and knots of the engine. Implementation of these requirements prevents a possibility of emergence of additional malfunctions when performing diagnostics and repair.
1. Before dismantle of any elements of a control system it is necessary to disconnect a wire of "mass" of the accumulator.
2. Launch of the engine without reliable connection of the accumulator is not allowed.
3. Disconnection of the accumulator from onboard network of the car at the working engine is not allowed.
4. At charging from an external source the accumulator needs to be switched-off from onboard network.
5. It is impossible to subject the control unit to influence of temperature above 80 °C, for example in the drying camera.
6. The design of connectors of plaits of wires of a control system of the engine provides connection only at a certain orientation. Both parts of connectors have the focusing elements. At the correct orientation connection is carried out without effort, the wrong orientation can lead to failure of a connector, the module or other element of system.
7. It is not allowed to disconnect or connect the control unit socket at the included ignition.
8. Before carrying out electrowelding works disconnect a wire of the accumulator and disconnect the socket from the control unit.
9. For an exception of corrosion of contacts when cleaning the engine the ferry do not direct a nozzle to system elements.
10. For an exception of mistakes and damage of serviceable knots use of the control and measuring equipment which is not specified in diagnostic cards is not allowed.
11. Measure tension by means of the voltmeter with a nominal internal resistance of 10 megohms/Century.
12. If use of the indicator with a control bulb is provided, it is necessary to use a lamp of small power. Application of lamps of big power, for example from a headlight, is not allowed. If the concrete type of the indicator does not make a reservation, it is necessary by the simplest check of a lamp to be convinced of safety of its application for control of chains of a control system. For this purpose it is necessary to connect the exact ampermeter (a digital multimeter to high internal resistance) consistently with a lamp of the indicator and a tax on this chain power supply of the accumulator. If the ampermeter shows current less than 0,25 And, application of a lamp is safe; if more than 0,25 And – application of a lamp is inadmissible.
13. Elements of electronics of control systems are calculated on very low voltage, are vulnerable for electrostatic categories.
For prevention of damage of system by an electrostatic charge it is forbidden:
– to concern contact probes of connectors or elements of the printed circuit board of the electronic block;
– to remove the metal case of the control unit;
– to take out a chip from a block of the memory device.

Diagnostic means
The main element of a control system is the microprocessor control unit using sensors for obtaining information on operation of the engine and various systems which it operates. The block is capable to perform diagnostics of elements of a control system of the engine (system of onboard self-diagnostics) in a certain volume.
At failure detection the control unit includes a diagnostic lamp of malfunction on the dashboard of the car and in his memory the code reflecting this malfunction is brought. It does not mean that the engine should be stopped immediately, and it is necessary to establish the reason of inclusion of a lamp in perhaps
short term. Operation of the car with not eliminated malfunctions can lead to deterioration in operational qualities of the engine, up to breakdown of mechanical parts and knots of electronic system.
The system of onboard self-diagnostics is capable to define the main probable causes of malfunction of a control system of the engine, however it is necessary to apply special diagnostic means to more exact definition of technical condition of the engine and elements of a control system. Devices for measurement of the actual physical quantities (fuel pressure, fuel consumption, temperature of cooling liquid, air, etc.), the universal and special diagnostic equipment (a digital multimeter, an electronic oscillograph, a diagnostic tester of DST-2M) concern to them.
In this manual the order of carrying out onboard self-diagnostics and a technique of diagnostics by means of DST-2M tester is stated.

System of onboard self-diagnostics
The electronic control unit carries out constant self-diagnostics for the majority of entrance and output signals and functions of management. These possibilities of diagnostics are supplemented with the procedures described in this manual. The control unit signals about the found malfunctions through the control lamp located in a combination of devices.
The system of onboard self-diagnostics is a part of the software of the electronic control unit which is responsible for control of parameters of a control system. It determines ranges of change of these parameters at observance of the corresponding regime operating conditions of the engine. An exit of controlled variables for the established borders indicates existence of malfunction in work of electronic system or the engine.
Each such error (malfunction) of system has definition and a code (number from 13 to 199). All mistakes arising in the course of work are fixed in system and in memory of the operating computer of the electronic block.
Single mistakes – the malfunctions appearing not more often than once two minutes. The subsystem of self-diagnostics lights a control lamp on 0,6 with, the code of malfunction is not brought in memory of the computer.
Repeated mistakes – the malfunctions which appeared more than once in two minutes. The subsystem of self-diagnostics brings codes of malfunctions in memory. If within two hours the code of malfunction did not repeat, then it is erased from memory of an electronic control unit.
The current mistakes – the malfunctions which are present at present at system. The subsystem of diagnostics includes a control lamp, indicating existence of malfunctions. The included diagnostic lamp signals about need of carrying out maintenance of the engine and system in the nearest future.

Diagnostic chain
The diagnostic chain is the means of communication of an electronic control unit with the external devices allowing to analyse work of a control system of the engine and includes the following components:
1. The control unit – a source of diagnostic information.
2. Wires from contact of the socket of the control unit to plugs of a diagnostic block.
3. A diagnostic block – the socket for connection of the diagnostic equipment.
4. Wires from contact of the socket of the control unit to a control lamp.
5. A control lamp (or a malfunction lamp) – means of display of information from the control unit.
All checks in system begin with definition of the correct work of a diagnostic chain.
As the electronic block has a set of entrance signals and a large number of various functions, attempt to break the sequence of performing diagnostics carries out can lead to the wrong conclusions, increase in holding time and even replacement of serviceable knots of system.

Work of a control lamp
In an operating mode at the included ignition and the idle engine the lamp flashes on 0,6 with and dies away if the subsystem of self-diagnostics did not define malfunctions in electric chains of a control system. If the lamp does not die away after inclusion of ignition or burns at the working engine, means it is necessary to carry out maintenance of system and the engine to perhaps short time and to eliminate malfunction.
In the mode of reading of codes of malfunctions the lamp displays numbers of the mistakes recorded and kept in memory of an electronic control unit by a self-diagnostics subsystem.

Mode of display of codes of malfunctions
The software of an electronic control unit contains in the structure diagnostics subsystem allowing to define the current mistakes in work of system and the block and to remember them in memory. Codes of mistakes can be read out from memory if to set to the control unit the mode of display of codes of malfunctions, or by means of a diagnostic tester of DST-2M.

Diagnostics by means of the self-diagnostics mode

Fig. 53. Electric circuit of a control system of engines 420.10-10 and 4213.10


For start-up of the mode of self-diagnostics of the MIKAS-7.2 block it is necessary to close at the included ignition and the idle engine contacts of 10 and 12 diagnostic sockets, the car which is under a cowl (see fig. 53, XS1).

Fig. 54. Connection of the button of diagnostics to the diagnostic socket (for the block "M1.5.4. At ABTPOH")


For start-up of the mode of self-diagnostics of the block "M1.5.4. At ABTPOH" it is necessary to contacts of 11 and 12 diagnostic sockets (see fig. 53) to connect the button of diagnostics (fig. 54) and to press twice it.
In this mode the subsystem of self-diagnostics operates inclusion switching off of a lamp of malfunction, highlighting the codes of mistakes which are stored in memory. At first the code 12 which is not a code of malfunction and testifies only to serviceability of a diagnostic chain and operability of a subsystem of self-diagnostics is given. If the code 12 is absent, then it is necessary to check a diagnostic chain and to eliminate the found malfunctions (see. "Possible malfunctions of system of injection of fuel").
The code 12 is highlighted three times in a row from a long pause in the following sequence: one inclusion of a lamp (the first figure of a code 1) – a short pause – two inclusions of a lamp in a row (the second figure of a code 2).
After a code 12 codes of malfunctions also on three times everyone are given: the inclusions corresponding by quantity to the first figure of a code – a short pause – the inclusions corresponding by quantity to the second figure of a code – a short pause – etc. After delivery of all codes of malfunctions the cycle is repeated. If in memory there are no codes of malfunctions, then only the code 12 is given.
Interpretation of codes of malfunctions is given in tab. 2.
Cleaning of codes of malfunctions. The memory storing codes of malfunctions can be cleared by means of a diagnostic tester of DST-2M, or having removed the plug of mass of the accumulator for the period of more than 10 pages. At the second way it is necessary to watch that ignition was switched off in order to avoid damage of the electronic block and to remember that at a detachment of the accumulator also other data of adaptive management can disappear (setup of the receiver etc.).

Self-learning ability of an electronic control unit
The electronic control unit in the course of work of a control system of the engine is capable to compensate rather small deviations caused by the changing working conditions (change of atmospheric pressure, air temperature, bad quality of gasoline etc.), aging and a razregulirovaniye of parts and knots of system and the engine (wear of nozzles, gaps in spark plugs and valves, violation of phases of gas distribution etc.). Such compensation is carried out due to fine tuning of parameters of the program of the control unit which remain in his memory.
When carrying out car repairs or cleaning of codes of malfunction with shutdown of the accumulator self-training parameters are lost. After connection of the accumulator for self-training of a control system it is necessary to warm up the engine up to the working temperature and to provide the movement of the car with moderate acceleration, and also work idling before restoration of normal working indicators.

Diagnostics of system by means of DST-2M tester
The electronic block allows to control parameters of management by means of a diagnostic tester of DST-2M representing the portable computer of special execution for diagnostic service of the cars equipped with electronic control systems of the engine. On diagnostic chains of DST-2M allows to contact the control unit on K-Line channel for performance of the following functions:
– reading and dumping of codes of malfunctions;
– check of operation of actuation mechanisms of system;
– choice and display of parameters of system;
– testing of power setting;

Note
Due to the constant improvement of the control unit and diagnostic unit the functions described in the present manual can differ from real opportunities of diagnostics of cars of early releases.

The diagnostic tester can work with various complete sets of electronic control systems. Such flexibility is provided with existence of set of program cartridges for a tester. Each cartridge belongs to a certain control unit and a certain complete set of a control system. The instruction for use of cartridges and the description of the interface of the user for DST-2M is provided in the operation manual on the device. In the present section functions of a tester are briefly described and the logic of search of malfunctions with application of DST-2M is specified.

Reading and dumping of codes of malfunctions
The tester has an opportunity to read out the codes of malfunctions which are saved up for operating time from memory of an electronic control unit. Display of codes on the screen of a tester and the reference on malfunctions can be requested by the user in the corresponding operating mode of a tester. The user can remove codes of malfunctions from memory of the control unit – such function is necessary, for example, after performing diagnostics and repair of system.
For display of any information the DST-2M device has to receive a signal from the control unit. If the control unit does not send a signal to a block of diagnostics or connection with the DST-2M device is faulty, the DST-2M device gives the message on lack of information exchange: in the right top corner of the screen of the display the cross hairs appears. In this case it is necessary to restore operability of a chain of diagnostics.
It is necessary to remember that DST-2M does not operate the engine, and only displays information which obtains from the control unit. It saves time at diagnostics and does not allow replacement of serviceable knots and details.

Check of operation of actuation mechanisms of system
This function allows to power or disconnect chains of actuation mechanisms, interfering directly with logic of operation of the control unit. Operability of a chain is estimated upon on/off actuation mechanism or to the signs characterizing it on/off.
The checked chains:
1. Management of a control lamp. The tester includes-switches off a control lamp.
2. Management of the relay of the fuel pump. Tester on/off relay of the fuel pump. On the working engine such procedure will lead to an engine stop. The mode on/off of a gasoline pump is useful when testing system of fuel feeding: check of the regulator of pressure, nozzles, tightness, etc.
3. Control of the idling regulator. Change of the set number of steps changes the frequency of rotation of the engine idling.
4. Management of fuel nozzles. On the working engine on/off any of nozzles leads to notable changes in operation of the motor.
If the checked device does not work, means it is necessary to check all knots of an electric chain of this device.

Choice and display of parameters of system
DST-2M tester on the communication line can read out  the system parameters determined and used by the control unit.
Record in memory of parameters carries out a tester cyclically in an operating mode of the engine. After that they can be looked through in the shot mode, comparing them to standard parameters of the serviceable engine (tab. 3). The logic of performing diagnostics according to the provided diagnostic schemes allows to determine by deviations of parameters malfunctions in a control system and the engine. The list of the key parameters available to reading is given below.
1. FREQ – the frequency of rotation of a bent shaft after launch of the engine.
The displayed data correspond to interpretation by the control unit of the actual frequency of rotation of a bent shaft of the engine on an entrance signal of the sensor of provision of a bent shaft.
Unexpected increase in turns at the constant angle of opening of a throttle indicates an electric hindrance in a chain of an entrance basic signal of provision of a bent shaft. Such hindrance usually is caused by the high-voltage wires which are not intended for a complete set of this engine.
2. FREQX – the frequency of rotation of a bent shaft idling.
The measured frequency of rotation of a bent shaft differs from the previous parameter in the bigger accuracy of representation.
3. JUFBXX – the set frequency of rotation of a bent shaft idling.
On the idling mode the control unit operates the frequency of rotation of a bent shaft. The set turns (an idling rotation frequency setting) is called the frequency of rotation of a bent shaft set by the control unit, for example, depending on temperature of cooling liquid.
4. EFREQ – an error of regulation of frequency of rotation of a bent shaft idling.
Difference between installation of frequency of rotation of idling and the measured frequency of rotation of a bent shaft idling. It is used for assessment of accuracy of management of rotation frequency on the mode of restriction of the minimum frequency of rotation of a bent shaft idling.
5. TWAT – temperature of cooling liquid.
Data represent interpretation by the control unit of a signal of the sensor of temperature of cooling liquid. The sensor is installed on the engine. The control unit measures tension on two contacts and will transform tension to value of temperature in degrees Celsius. Values have to be close to air temperature when the engine is not heated-up, and have to increase in process of warming up of the engine. After launch of the engine temperature has to increase evenly to 85–95 °C and then be stabilized when opening the thermostat.
6. TAIR – air temperature on an admission.
Data represent interpretation by temperature sensor signal control unit on an admission. The sensor is installed on the inlet pipeline. The control unit measures tension on contacts of the sensor and will transform tension to value of temperature in degrees Celsius. Values have to be approximately equal to the air temperature when the engine is not heated-up, and have to increase in process of warming up of the engine. This parameter is used for determination of air temperature on an admission in cylinders of the engine and for introduction of adjustments to fuel feeding and ignition.
7. JAIR – a mass consumption of air.
Parameter represents a mass consumption of air via the sensor of a mass expense in kg/h.
8. JGBC – cyclic filling of the cylinder air for fuel calculation.
The real filling of the cylinder of the engine air used for calculation of basic value of size of supply of fuel.
9. NFRGBC – number of a regime point of engine management. It is set by two parameters:
NFREQ – the quantized frequency of rotation of a bent shaft;
NGBC – quantized cyclic filling by air of cylinders of the engine.
10. THR – the provision of a butterfly valve.
Parameter represents the size of opening of a butterfly valve counted by the control unit as function of tension of an entrance signal of the sensor of provision of a butterfly valve. 0% correspond to completely closed butterfly valve, 100% – completely open.
11. COEFFF – fuel feeding regulation coefficient.
The transfer coefficient of fuel feeding depending on the frequency of rotation and cyclic filling of cylinders of the engine is displayed by air. Represents the correcting program parameter.
12. VALF – a ratio air-fuel.
Ratio of air and fuel in air a toplivosmesa, set by the control unit. Represents the current set value of coefficient of excess of air in mix.
13. BITPOW – a sign of transition to power enrichment of mix and power value of a corner of an advancing of ignition (yes/no).
Transition on power the mode of regulation of fuel feeding and ignition is displayed. Transition depends on the current values of frequency of rotation of the engine and the provision of a butterfly valve.
14. BLKINJ – a sign of shutdown of fuel feeding when braking (yes/no).
Displays shutdown of fuel feeding when braking the car the engine. Yes value corresponds to zero supply of fuel.
15. INJ – injection impulse duration.
Duration of an impulse of injection represents duration (in milliseconds) the included condition of a nozzle set by the command of the control unit. The system of electronic injection of fuel operates structure of an air toplivosmesa by regulation of duration of the included condition of a nozzle. The big duration of the included state gives bigger amount of the given fuel and enrichment of mix.
16. UOZ – the ignition advancing corner (IAC).
The current value of a corner of an advancing of ignition is displayed. Compliance of indications can be checked by means of a stroboscope.
17. UOZOC – the amendment of UOZ ("octane proofreader").
Displays the value of shift of a corner of an advancing of ignition entered by means of the DST-2M diagnostic unit into non-volatile memory of the control unit. Operation of the amendment extends to the load and power modes. The amendment is subtracted taking into account a sign from the value of a corner of an advancing of ignition set by the control unit.
For example: the amendment -3 ° п.к.в is entered. (an angle of rotation of a bent shaft) – it means that real value of a corner of an advancing of ignition is defined by a formula:
UOZ = Uozbloka of management – (–3) = Uozbloka of management +3 ° п.к.в.
18. DET – a detonation sign.
Reflects operation of the engine with a detonation or without it.
19. DUOZ1 – UOZ shift on a detonation for the first cylinder.
Reflects the correction of a corner of an advancing of ignition entered by the control unit in the first cylinder of the engine on the basis of a detonation in this cylinder.
20. DUOZ2 – UOZ shift on a detonation for the second cylinder.
Reflects the correction of a corner of an advancing of ignition entered by the control unit in the second cylinder of the engine on the basis of a detonation in this cylinder.
21. DUOZ3 – UOZ shift on a detonation for the third cylinder.
Reflects the correction of a corner of an advancing of ignition entered by the control unit in the third cylinder of the engine on the basis of a detonation in this cylinder.
22. DUOZ4 – UOZ shift on a detonation for the fourth cylinder.
Reflects the correction of a corner of an advancing of ignition entered by the control unit in the fourth cylinder of the engine on the basis of a detonation in this cylinder.
23. UACC – tension in onboard network. Reflects tension measured by the control unit in onboard network.
24. RCOD – correction coefficient WITH idling.
Reflects the signal size from an adjustment potentiometer WITH transformed to shift concerning zero. Negative shift corresponds to decrease in supply of fuel of the size which is rather theoretically counted in the control unit, positive shift – to increase in supply of fuel.
25. FSM – the current provision of RDV.
This parameter reflects the current provision of RDV in steps. The maximum opening of RDV corresponds to 255 steps, the closed state corresponds to one step.
26. JQT – fuel consumption.
This calculated parameter reflects hour fuel consumption (l/h) via the engine. Value has to correspond to a real volume consumption of gasoline which can be measured by means of a flowmeter.
27. JATHR – tension on the sensor of provision of a butterfly valve (mV).
28. JATWAT – tension on the sensor of temperature of liquid (mV).
29. JATAIR – tension on the sensor of the air temperature (mV).
30. JARCO – tension on an adjustment potentiometer FROM (mV).
Some standard parameters of a control system of the engine and range of their changes at inclusion of ignition and during the operation of the engine are idling specified in tab. 3.
 Testing of power setting. The tester allows to determine integrated parameters of a control system on separate test modes of the engine on which it is possible to estimate serviceability of the engine, its control system, and also the main units of electric equipment of the car.
 Test of scrolling of the engine. It is carried out in the mode of starter scrolling of the engine at completely open butterfly valve. Scrolling time not less than 3 seconds.
The tester counts averages the frequency of rotation of the FREQs crankshaft and tension of onboard network UACCs.
For the hot engine
FREQs> 200 min.-1, UACCs> 10 Century.
If with UACCs <9,0 B, then it is necessary to charge the rechargeable battery or to replace it.
If UACCs> 10,0 B, and FREQs <100 min.-1, then it is necessary to check serviceability and contacts of power wires of "weight", the weights switch, and also serviceability of a starter and chains of its food and management.
 Test of launch of the engine. It is carried out in the mode of usual launch of the engine.
The tester counts the average frequency of rotation of the bent shaft FREQs, average tension of onboard network UACCs and time of launch of the TIMST engine.
For the hot TIMST engine <1,5 pages.
If TIMST> 3,0 with, then it is necessary to check engine power supply systems air and fuel, and also serviceability of system of ignition and to eliminate malfunctions.
 Test of mechanical losses. It is carried out in the mode of idling of the engine. For this purpose by means of the drive of a butterfly valve the frequency of rotation of a bent shaft higher than 4000 min.-1 are determined, then the butterfly valve is sharply closed.
The tester defines time of braking of the TIMTR engine from 4000 to 2000 min.-1. For the hot TIMTR engine <2,5 pages.
If TIMTR> 3,5 with, it is necessary to check a condition of conrod and piston group of the engine and if necessary to repair.
 Functional test of executive mechanisms. The program of the test of executive mechanisms is carried out only for the control unit "by M1.5.4. At ABTPOH".
The test can be begun as by means of a tester, having chosen the corresponding command from its menu of management, and by means of the button of the self-diagnostics connected to the diagnostic socket according to the scheme specified fig. 54.
For start-up of the functional test it is necessary to include ignition and to press two times the self-diagnostics button. Consistently join: coils of ignition, nozzle and regulator of additional air. During implementation of the functional test the lamp of diagnostics is included, and upon completion of the test – is switched off. Repeated double pressing of the button leads to repeated execution of the test of executive mechanisms. An exit from the test is carried out by switching off of ignition.
It is not recommended to begin start of the test of executive mechanisms at once after unsuccessful launches of the engine as it can lead at turning on of coils of ignition to explosion of vapors of gasoline which can collect in system of production of the fulfilled gases. In this case before start-up of the test it is necessary to execute 2–3 times a purge of cylinders air and to sustain a pause of 10-15 min. for evaporation of the remains of gasoline.
If after inclusion of ignition the malfunction lamp joins again and burns, signaling about existence of malfunction in a control system of the engine, then execution of the test of executive mechanisms is blocked and joins the self-diagnostics mode with a conclusion of light codes of malfunction.
To dump the malfunction codes which are saved up in the control unit in the course of operation of the engine it is necessary or to disconnect "weight" on 20-30 with, and then again to include ignition, or after inclusion of ignition in the mode of a conclusion of light codes of malfunction to press once diagnostics button. If there are no malfunctions in system, then short-term flashes are brought to a lamp of malfunction.