This article describes the diagnostic procedure used for the electronic control unit (ECU) EMS 31.32 of the electronic engine management system (ESM) K7M and K4M
Necessary diagnostic equipment and devices:
- - diagnostic device DST-12 (RF90 firmware);
- - multimeter;
- - contact board Ele. 1497;
- - universal contact board Ele. 1681.
The Ele1497 contact board or the Ele1681 universal contact board must be used if the data obtained with the diagnostic tool requires checking electrical circuits.
Tests using the Ele1497 or Ele1681 contact board must only be performed with the battery disconnected.
The contact boards are intended for use with a multimeter only. It is prohibited to connect a 12 V power source to the points being checked.
General instructions for performing diagnostics
To diagnose the ECM, it is necessary to connect the diagnostic tool, turn on the ignition and perform the necessary operations (check for faults, check the compliance of the data transmitted by the controller).
Checking for fault codes
Faults are defined as "current" (currently active) or "stored" (non-permanent, i.e. appeared under certain conditions and then disappeared or continue to occur, but are not detected under current conditions).
The fault status ("current fault" or "stored fault") is displayed on the diagnostic tool and must be taken into account without affecting the ECM elements.
For a "current" fault, diagnostics must be carried out in accordance with the procedure given in the article "Codes fault codes and troubleshooting of the Lada Largus car".
For a "saved" fault, perform diagnostics in accordance with the procedure given in the "Instructions" article of the "Fault codes of the ECM and troubleshooting of the Lada Largus car" section.
If the fault is confirmed after performing the operations given in the "Instructions" subsection, the fault is recognized as current.
Diagnose in accordance with the procedure given in the "Fault codes of the ECM and troubleshooting of the Lada Largus car" article for the corresponding fault.
If the fault is not confirmed, it is necessary to check:
- - electrical circuits related to the faulty ECM device;
- - connectors of these circuits (for signs of oxidation, deformation of contacts, etc.);
- - resistance of the faulty devices;
- - condition of wires (is there melted or damaged insulation, signs of bending, etc.).
Checking the compliance of data transmitted by the ECU
The purpose of the compliance check is to check the data displayed by the diagnostic tool (system states and parameters) that are outside the tolerance and do not lead to the appearance of fault codes.
Therefore, this stage allows:
- - to diagnose such faults that do not lead to the appearance of a fault code, but may correspond to the owner's complaint;
- - to check the operability of the system and make sure that the fault will not reappear after repair.
This section presents diagnostics of states and parameters, as well as the conditions for its implementation.
If the state does not correspond to the norm or if the parameter is outside the tolerance, see the corresponding items diagnostics.
If no faults are found during the diagnostic tool check, but the fault remains according to the owner's complaint, then the corresponding fault finding procedure should be used to eliminate the fault.
Preliminary checks
When performing diagnostics, repairs or searching for the cause of a fault, it is always necessary to thoroughly inspect the underhood space.
All vacuum hoses should be checked for pinching, cuts or disconnection.
All electrical wiring located in the underhood space should be checked for secure connections, the absence of burnt, frayed or deformed wires, and the absence of contact of wires with sharp edges or the exhaust manifold.
Check the ground wire contacts for contamination and a secure connection to ground.
Check the wire harnesses for damage. Check the integrity of the wire insulation.
Check the contacts of the connectors and the wiring harness pads for deformation and oxidation.
Checking the wiring harnesses and system components
Finding faults that are intermittent in nature should begin with checking the problematic electrical circuits.
When checking electrical circuits, pay attention to the following:
- - the terminals are securely crimped on the wire, but the wires are not pinched;
- - the terminals are securely fixed in the block;
- - the terminals are not deformed;
- - there is no dirt, moisture, or corrosion on the terminals;
- - the block body does not show signs of damage (cracks, deformation, melting);
- - the terminals provide a reliable connection, the terminals are not recessed into the block;
- - there is no damage to the insulation in the wires;
- - there are no kinks in the wires inside the insulation.
If intermittent faults occur, it is always necessary to check the integrity of the ground circuits of the engine management system.
It is necessary to make sure that the ground terminals are securely fastened to the car body, the terminals of the power and ground wires are securely fastened to the battery battery.
With the ignition on, and then with the car running, you need to move the wires, starting from the connectors, along the entire harness route, monitoring the operating parameters of the engine management system using a diagnostic device.
When checking the resistance of a circuit, first check the integrity of the entire circuit, then in individual sections. The loss of integrity of the electrical circuit can be caused by the following reasons:
- - disconnection of the harness block;
- - poor connection of the harness block;
- - contamination, oxidation, corrosion of contacts;
- - deformation of contacts;
- - damage to the wire.
Determine whether there is a short circuit in the circuit to "ground" or to the "on-board network".
If a fault is detected in the wiring harness, eliminate it or replace the wiring harness.
Safety measures
When working on the car, the following requirements must be observed:
Before dismantling the controller, disconnect the "ground" wire from the battery.
It is not allowed to start the engine without a secure connection of the battery.
It is not allowed disconnecting the battery from the on-board network with the engine running.
When charging, the battery must be disconnected from the on-board network.
It is necessary to monitor the reliability of the wire harness contacts and maintain the cleanliness of the battery terminals.
The design of the wire harness connectors provides for their connection to the mating part only with a certain orientation.
With the correct orientation, the connection of the harness connector to the mating part is performed without force. Connection with the wrong orientation of the connector may result in failure of the connector, module or other system element.
Connection or disconnection of the connectors of the ECM elements is not allowed with the ignition on.
Before performing electric welding work, it is necessary to disconnect the wires from the battery and the connector from the controller.
To prevent corrosion of the contacts, when washing the engine with a jet of water under pressure, do not direct the spray at the system elements.
Voltage measurements should be performed using a digital voltmeter with a nominal internal resistance of more than 10 MOhm.
To prevent damage to electronic components by electrostatic discharge, it is prohibited to disassemble the metal case of the controller and touch the connector plugs.
All work with fuel system components should be carried out wearing protective gloves.
When disconnecting fuel lines, take measures to prevent fuel spillage. Close the fuel line openings using the standard plugs
System operation
Features of the distributed fuel injection system:
The 90-channel ECU "EMS 31.32" controls the fuel injection and ignition systems.
The system does not have a camshaft position sensor.
Therefore, synchronization of the system with the engine operation is carried out programmatically using a signal from the crankshaft position sensor. Fuel injection is carried out sequentially-parallel in accordance with the firing order of the cylinders.
The idle mode is adjusted depending on:
- - the state of the air conditioning system (whether the air conditioning is working or not);
- - the operation of the power steering system;
- - the load on the on-board network.
The degree of cyclic opening (CDO) of the electromagnetic valve of the adsorber purge depends on the speed of the crankshaft and the operating conditions of the engine.
Use of two oxygen sensors installed before and after the catalytic converter.
Automatic configuration for air conditioning operation by exchanging signals between the ECU. Changing the configuration is not possible (including using a diagnostic tool).
Electronic anti-theft immobilizer system
Vehicles are equipped with an electronic anti-theft immobilizer system. To operate the ECU, it is necessary to enter the code of the electronic anti-theft engine start blocking system into it.
Replacing the ECU
I supply the ECU without the entered code for the electronic immobilizer system of the engine start. When replacing the ECU in a new unit, it is necessary to enter this code, then make sure that the electronic immobilizer system of the engine start is operational.
To enter the code, it is necessary to turn on the ignition for a few seconds, and then turn it off.
The ECU ECM stores the immobilizer code for the entire service life.
This system does not have an unlock code.
It is prohibited to carry out tests using ECUs taken from a warehouse or from another car and subject to return. Codes entered in these ECUs cannot be deleted.
Checking the ECU status (code entered or not entered)
Check the ECU status using the diagnostic tool:
- - connect the diagnostic tool to the diagnostic connector;
- - turn on the ignition;
- - select on the diagnostic tool: "Parameters" mode - "General view".
If the ET341 "Engine immobilizer code entered" status is displayed as "NO", this indicates that the code has not been entered in the ECU.
If the ET003 "Engine immobilizer" status has the "ACTIVE" characteristic, then starting the engine is not possible.
Control of the refrigeration circuit of the automatic climate control system (SAUKU)
The operation of the refrigeration circuit of the SAUKU is ensured by the following units:
- - control unit of the SAUKU;
- - air conditioning compressor;
- - ECU ECM.
The system operates in automatic mode, i.e. the amount of cold air is dosed in accordance with the set temperature.
Principle of operation of the system
The air conditioner is turned on by pressing the air conditioner switch "AC", located on the instrument panel in the car's interior.
In this case, the request to turn on the air conditioner comes via a wired circuit to the ECU ECM, which allows or prohibits the activation of the air conditioner compressor depending on the engine operating mode and the state of the SAUKU.
The ECU ECM prohibits the activation of the air conditioner compressor if the following conditions are met:
- - rotation speed crankshaft below a certain value;
- - engine load above a certain value (for example, when the accelerator pedal is pressed sharply, on a steep climb or when the vehicle is heavily loaded);
- - refrigerant pressure in the air conditioning system is above a certain value.
If there are no prohibiting conditions, the ECM turns on the power relay, which supplies supply voltage to the actuator of the air conditioning compressor.
Engine idle speed correction
Communication between the pressure sensor in the power steering system (PS) and the ECM (if the vehicle is equipped with PS)
The ECM receives a signal from the PS pressure sensor (monitored by the diagnostic tool: "Parameters" mode - "General view" - state "ET297 - Pressure sensor in the power steering system" - has the "YES" characteristic when rotating steering wheel).
The signal parameters depend on the pressure of the working fluid in the hydraulic circuit of the power steering and on the viscosity of the working fluid. The higher the pressure, the more energy the power steering pump consumes.
At maximum load conditions, the idle speed can be additionally increased by approximately 100 rpm.
Idle speed correction depending on the battery voltage and the load on the on-board network
If the battery is weakly charged, then when electrical consumers are turned on, the voltage drop on it is compensated by idle speed correction.
For this purpose, the engine crankshaft speed at idle speed increases, as a result of which the generator rotor speed and, accordingly, the battery charging current increase.
The lower the battery voltage, the greater the idle speed correction.
Thus, the idle speed correction is a variable value. Correction begins when the battery voltage drops below 12.8 V.
The nominal idle speed of the crankshaft as a result of correction can be increased by no more than 150 rpm.
Adaptive correction of engine idle speed
Under normal operating conditions of an engine warmed up to operating temperature, the value of the degree of opening of the idle speed control valve (IAC) changes from the upper to the lower value to ensure the nominal idle speed.
Due to the variety of engine operating conditions (run-in, mechanical wear, etc.), the value of the degree of opening of the IAC on idle speed may be near the upper or lower limit.
Adaptive correction of the degree of opening of the IAC at idle speed allows to compensate for operational changes in the engine's demand for air in order to set the degree of opening of the IAC to the average nominal value.
This correction is made if the coolant temperature is above 80 °C, at least 20 s have passed since the engine was started, and if the system is in the nominal idle speed regulation mode.
Values of the degree of opening of the IAC at idle speed and its adaptive correction
- PR145 "Engine speed" 752 rpm
- PR432 "Current degree of opening of the IAC" 8 % < X < 20 %
- PR431 "Adaptive IAC opening degree" %
After each engine stop, the ECU returns the IAC stepper motor valve to its original position to the lower stop within 8 seconds.
Interpretation of these parameters
In case of excess air (due to air suction, incorrect throttle position adjustment, etc.), the engine speed at idle increases, and the IAC opening degree value decreases to maintain the nominal idle speed. The adaptive correction value of the IAC opening degree decreases to return the IAC opening degree to the average value.
In case of insufficient air (contamination, etc.), the reverse strategy is applied. The IAC opening degree value increases. The value of the adaptive correction of the degree of opening of the IAC increases to return the degree of opening of the IAC to the average value.
After deleting information from the ECU memory, it is necessary to restore the function of adaptive correction of the engine idle speed, for which the following procedure must be performed:
- - start and then stop the engine to adjust the position of the IAC stepper motor;
- - start the engine again and leave it to idle until the nominal idle speed mode is established.
Adjusting the composition of the working mixture
Heating the oxygen sensors
The ECU turns on the heating of the oxygen sensors:
- - for the upper sensor immediately after starting the engine,
- - for the lower sensor after a certain time of engine operation (excluding the time of operation at idle) according to the program depending on the coolant temperature fluid.
The oxygen sensors are heated continuously until the engine stops.
Upstream oxygen sensor signal voltage
The diagnostic tool displays parameter PR098 "Upstream oxygen sensor signal voltage". The displayed value is the voltage (in millivolts) of the output signal sent to the ECU by the oxygen sensor located before the catalytic converter.
The ECM uses the upstream oxygen sensor signal in its closed-loop control of the working mixture composition based on the oxygen content in the exhaust gases.
The upstream oxygen sensor signal voltage should change rapidly in the range:
- - 20 mV + 50 mV for a lean working mixture;
- - 840 mV ± 70 mV for a rich working mixture.
The smaller the difference between the minimum and maximum values, the less accurate the information from the sensor (usually this difference is 500 mV).
Downstream Sensor Signal Voltage
The scan tool displays parameter PR099 "Downstream O2 Sensor Signal Voltage". The displayed value is the voltage (in millivolts) of the output signal sent to the ECU by the oxygen sensor located after the catalytic converter.
The functions of this sensor include diagnosing the catalytic converter and implementing a second, more accurate, control of the mixture enrichment (slow regulation system).
This function is activated only after a certain period of operation of the engine warmed up to operating temperature, and is not implemented at idle.
At a steady driving speed, the signal voltage of the downstream oxygen sensor should change in the range of 600 mV ± 100 mV.
During braking, the signal voltage should be below 200 mV.
The voltage value shown by the diagnostic tool at idle is not used for ECM diagnostics.
Correction of the working mixture
The value of parameter PR438 "Fuel mixture correction value" displayed by the diagnostic tool is the average value of the fuel injection time correction made by the ECU depending on the information on the oxygen content in the exhaust gases transmitted by the oxygen sensor installed before the catalytic converter.
Correction value for the nominal value of 128 and for the extreme positions of 0 and 255:
- - value below 128 - request for lean;
- - value above 128 - request fors to enrichment.
Start of mixture control
Entering the mixture control mode occurs if the coolant temperature is above 22 °C and 28 s have passed since the engine was started.
Outside the mixture control phase, the correction value is 128.
Phase "opening the mixture control circuit"
When regulating the mixture, the ECU does not take into account the oxygen sensor signal voltage in the following cases:
- - at full load - the correction value is higher than 128;
- - during sharp acceleration - the correction value is higher than 128;
- - during braking with the receipt of the "idle" signal (stopping fuel injection) - the correction value is 128;
- - in case of a malfunction of the upper oxygen sensor - the correction value is 128.
Backup mode in case of oxygen sensor malfunction
If the voltage of the signal coming from the upstream oxygen sensor in the mixture control mode does not correspond to the set values (changes very slightly or does not change at all) and this malfunction is recognized as "current" for 10 s, the ECU switches to the backup mode and information about this malfunction is entered into the ECU memory.
When a "current" oxygen sensor malfunction is detected, the ECU switches to the mode of operation with an open mixture control circuit. In this case, the value of parameter PR438 "Fuel mixture correction value" is equal to 128.
Adaptive air-fuel mixture correction
When controlling the air-fuel mixture with exhaust gas oxygen content feedback (see section "Fuel mixture correction"), the air-fuel mixture correction function changes the fuel injection duration to ensure an excess air ratio as close to 1 as possible. In this case, the average correction value is close to 128, with limit values of 0 and 255.
Operational changes in the parameters of the ECM and engine components can lead to a shift in the correction values to 0 or 255 in order to ensure an excess air ratio close to 1.
Adaptive air-fuel mixture correction allows you to configure the injection algorithm so as to obtain a value of parameter PR438 "Fuel mixture correction value" equal to 128, and use this value as the main one, as when enrichment and leanness of the mixture.
There are two modes of adaptive correction of the working mixture composition regulation:
- - adaptive correction, carried out mainly at medium and significant engine load - "adaptive correction of the working mixture composition in load modes";
- - adaptive correction, carried out mainly at idle and low engine load - "adaptive correction of the working mixture composition at idle".
Adaptive corrections take an average value of 128 after ECU initialization (erasing information from ECU memory). During vehicle operation, adaptive corrections change and can take the following values:
- - PR139 "Adaptive correction of the working mixture composition in load modes" 64 < X < 192
- - PR140 "Adaptive correction of the composition of the working mixture at idle" 64 < X < 192
Adaptive correction is performed only on an engine warmed up to operating temperature in the mixture control mode based on the oxygen sensor signal, and only at a given pressure range in the intake manifold.
In order for the adaptive correction to begin compensating for deviations from the norm in the mixture composition due to operational changes in the parameters of the ECM elements and the engine, it is necessary for the engine to operate for some time in the mixture control mode at different vacuum values in the intake manifold.
After initializing the ECU (returning the adaptive mixture corrections to a value of 128), a special road test must be carried out.
Road test
Conditions:
- - the engine is warmed up (coolant temperature > 80 °C);
- - crankshaft speed engine speed should not exceed 4000 rpm.
It is recommended to start this road test at low engine speed, in 3rd or 4th gear and with very smooth continuous acceleration to stabilize the required pressure for 10 seconds in each range (see table below).
On the diagnostic tool, select "Parameters" - "General view" - parameter "PR421 - Intake manifold pressure".
The test pressure ranges for the K7M engine are listed below.
- Range #1, mbar: - 258 - 410; - Average 334;
- Range #2, mbar: - 410 - 528; - Average 469;
- Range #3, mbar: - 528 - 646; - Average 587;
- Range #4, mbar: - 646 - 764; - Average 705;
- Range #5, mbar: - 764 - 873; - Average 818
After this test, the adaptive correction function starts to operate.
The value of "Adaptive correction of the working mixture composition at idle" changes more significantly at idle and low loads, and the value of "Adaptive correction of the working mixture composition at load modes" at medium and high loads.
Both types of correction are carried out over the entire range of pressure changes in the intake manifold.
Continue the test, driving under normal conditions at a constant and variable speed for a distance of 5 - 10 km.
After the test, check the adaptive correction values at load modes. Initially equal to 128, they should change.
Otherwise, conduct a road test again and check the adaptive correction values.
Features of the on-board diagnostics system
This vehicle has an on-board diagnostics system (OBD), which turns on a warning lamp in the instrument cluster (ON-BOARD diagnostics system warning lamp) when it detects that the permissible threshold of exhaust gas toxicity has been exceeded.
This warning lamp notifies the driver of the need for vehicle repair.
The on-board diagnostics system includes the following types of diagnostics:
- - diagnostics of ECM components;
- - diagnostics of mixture misfires;
- - functional diagnostics of the upper oxygen sensor;
- - diagnostics of the catalytic converter.
Diagnostics of components is carried out on an ongoing basis ECM and misfire diagnostics.
The upstream oxygen sensor and catalytic converter functional diagnostics are performed once per trip if the corresponding diagnostic conditions are met:
- - air and coolant temperature conditions,
- - driving speed within a certain range;
- - engine operating conditions (intake manifold pressure and engine crankshaft speed within a certain range of values, stability of operation);
- - a certain initial time delay has expired.
In addition, the on-board diagnostics system is a means of detecting faults in electrical circuits. In this case, the following is performed:
- - storing faults detected by the on-board diagnostics system;
- - turning on the on-board diagnostics system warning light (lighting up with a constant or flashing light depending on the type of fault).
It is necessary to keep in mind that some defects may only appear while driving after programming the correction parameters.
At the end of each diagnostic test, do not turn off the ignition until the result is read on the diagnostic device. Turning off the ignition causes incorrect interpretation of the results.
Any electrical faults that cause the emission threshold to be exceeded will cause the OBD warning light to come on.
Conditions for turning on the OBD warning light
The OBD warning light will come on if the OBD has detected the same fault for three consecutive trips or if a fault is detected in the electrical circuit.
The OBD warning light will flash when misfires that are destructive to the catalytic converter are detected.
The OBD warning light will go off if the fault detected by the OBD system does not occur for three consecutive trips (but the fault information remains in the ECM memory).
The fault information will be cleared from the ECM memory if the fault does not occur for 40 consecutive tests or using a diagnostic tool.
Conditions for performing diagnostics using the on-board diagnostics system
The on-board diagnostics system starts functioning after the ignition is turned on and the following conditions are met:
- - the intake air temperature detected by the sensor is between - 6 °C and 119 °C;
- - the coolant temperature detected by the sensor is between - 6 °C and 119 °C;
- - the atmospheric pressure detected by the sensor with the engine off is higher than 775 mbar (at an altitude below 2500 m).
For the on-board diagnostics system to function correctly, there must be no faults in the electrical circuits of the ECM, even if the OBD warning lamp does not light.
Diagnostics of the oxygen sensor and catalytic converter cannot be performed simultaneously.
When diagnosing the catalytic converter and oxygen sensor, the purge of the adsorber is stopped, and the adaptive pairs meters of the working mixture correction are fixed according to their last values.
Test procedure:
- - eliminate faults in electrical circuits;
- - use the diagnostic tool to erase information about faults from the ECU memory;
- - if necessary, program all ECU settings.
Initialization of the on-board diagnostics system using command modes allows you to:
- - delete faults from the ECU memory;
- - delete programmed ECU values from the memory (if the programmed values of the idle speed controller, the marker section of the flywheel ring gear, or the engine crankshaft position and speed sensor, etc., could have been distorted during repair work).
To do this, select the mode on the diagnostic tool "Additional tests" - "ECU reset".
Programming required for troubleshooting with the on-board diagnostics system
Programming the engine crankshaft torque (after programming, the ET061 status "Recognition of cylinder #1 Irregularity adaptation" = "Yes", with the engine running).
Program as follows:
- - perform engine braking with fuel injection interruption (i.e. i.e. without pressing the brake, accelerator and clutch pedals) in 2nd, 3rd, 4th or 5th gear from 3500 - 3000 rpm for at least 2 seconds;
- - perform engine braking with fuel injection stopped (i.e. without pressing the brake, accelerator and clutch pedals) in 2nd, 3rd, 4th or 5th gear from 2400 - 2000 rpm for at least 3 seconds.
Programming the parameters of the adaptive correction of the composition of the working mixture:
- - to perform this programming, it is necessary to perform a road test, observing the required pressure ranges in the intake manifold (see the section "Adaptive correction of the composition of the working mixture").
After performing the specified programmings ET422 "Misfire diagnostics results taken into account" status should have the "Yes" characteristic.
Misfire diagnostics
Diagnostics allows you to detect:
- - spark plug contamination;
- - malfunctions in the fuel supply system (pressure regulator, fuel pump, fuel injectors, etc.);
- - malfunctions in the electrical connections in the ignition and fuel supply systems (poor connection of high-voltage wires to spark plugs, wiring harness pads to injectors, etc.).
Diagnostics are performed by measuring the instantaneous speed of the engine crankshaft. A sharp drop in torque indicates that the fuel mixture is not burning in a particular cylinder.
This diagnostics is performed continuously while the vehicle is moving. Detection of a fault during this diagnostic procedure prohibits the system from performing other diagnostics.
Misfire detection diagnostics can detect two types of faults:
- - misfires that lead to the destruction of the catalytic converter (cause the on-board diagnostics warning light to immediately flash);
- - misfires that lead to exceeding the permissible toxicity threshold (cause the on-board diagnostics warning light to light continuously if misfires are detected during three consecutive trips).
Fault detection conditions
Use the diagnostic tool to ensure that the crankshaft torque and adaptive air-fuel ratio correction parameters have been programmed:
- - ET061 status "Recognition of cylinder #1 Adaptation of irregular rotation" has the characteristic "Yes";
- - status ET422 "Results of misfire diagnostics taken into account" has the characteristic "Yes".
The diagnostic test for misfires is performed with the engine idling for 11 minutes after the coolant temperature exceeds 75 °C in three engine speed ranges from idle to 4500 rpm.
If after the test the diagnostic tool has detected misfires, then refer to the interpretation of faults DF123 "Misfires leading to an increase in the content of toxic substances in the exhaust gases" and DF124 "Misfires leading to failure of the catalytic converter".
Confirmation of execution test:
- - the ET061 status "Recognition of cylinder #1 Adaptation of rotation irregularity" has the characteristic "Yes";
- - the ET422 status "Results of diagnostics of mixture misfires taken into account" has the characteristic "Yes";
- - the "Yes" characteristic;
- - no faults are detected and the on-board diagnostics warning lamp is off.
Catalytic converter diagnostics
Catalytic converter diagnostics are performed to detect a malfunction that causes the exhaust gas toxicity threshold allowed by the on-board diagnostics system to be exceeded.
The oxygen capacity of the catalytic converter is an indicator of its condition.
As the catalytic converter ages, its oxygen capacity decreases in the same way as its ability to neutralize exhaust gases.
Conditions for starting diagnostics
Catalytic converter diagnostics can only be performed after the engine has been running for the time specified in the following table, if the following conditions are met:
- - there are no faults in the electrical chains;
- - engine crankshaft torque programming has been completed;
- - no misfires detected;
- - catalytic converter diagnostics were not performed after the ignition was turned on;
- - the main and dual exhaust gas oxygen control circuits are activated;
- - coolant temperature is above 75 °C.
- K7M engine;
- Speed 63/130 km/h;
- Crankshaft speed - 1856/3808 rpm;
- Intake manifold pressure - 400/750 mbar;
- Duration of stable engine operation - 11 s;
- Temporary delay before resolution - 17 min
Troubleshooting
Diagnostics is performed in 5th gear at a constant speed of 70 km / h.
If the conditions for starting diagnostics are met, the mixture enrichment process is delayed in time, which leads to the flow of oxygen portions into the catalytic converter.
If the catalytic converter is in good condition, it absorbs oxygen and the signal voltage of the lower oxygen sensor remains at an average level.
If the catalyst has exhausted its resource, then oxygen is not absorbed and the lower oxygen sensor begins to work intermittently.
The signal voltage of the oxygen sensor will fluctuate. If the fault is confirmed three times in a row, the on-board diagnostics warning light comes on.
The test duration must not exceed 52 seconds.
If after performing the test the diagnostic tool detects a functional fault of the catalytic converter, refer to the procedure for handling fault DF394 "Catalytic converter malfunction".
Confirmation of test execution:
- - status ET345 "Catalytic converter diagnostics taken into account" has the characteristic "Yes";
- - status ET349 "Catalytic converter diagnostics performed" has the characteristic "Yes";
- - no functional fault of the catalytic converter was detected.
Oxygen sensor diagnostics
The purpose of the oxygen sensor diagnostics is to sensor is to determine a malfunction that leads to exceeding the permissible threshold of toxicity of exhaust gases for CH emissions.
Oxygen sensors can have two types of malfunction:
- - mechanical malfunction of an electrical element (breakdown, wire break), leading to a malfunction in the electrical circuit;
- - chemical malfunction of a component, which leads to an increase in the response time of the sensor, and, consequently, to an increase in its response period.
Diagnostics of oxygen sensors is performed by measuring and comparing the response periods of oxygen sensors.
After performing a diagnostic test, the obtained response periods of the sensor are averaged (discarding parasitic effects), and the obtained value is compared with the average threshold period embedded in the on-board diagnostics system.
Conditions for performing a diagnostic test
Diagnostics of the oxygen sensor is performed after how the engine has worked for the time specified in the following table, if the following conditions are met:
- - there are no faults in the electrical circuits;
- - the engine crankshaft torque programming has been performed;
- - no misfires have been detected;
- - the oxygen sensor diagnostics have not been performed after the ignition has been turned on;
- - the coolant temperature is above 75 °C.
- K7M engine;
- Speed 63/130 km/h;
- Crankshaft speed - 1856/3808 rpm;
- Intake manifold pressure - 380/850 mbar;
- Duration of stable engine operation - 8 s;
- Time delay before resolution - 14 min
Troubleshooting
Diagnostics are performed at a stable speed and within the time specified in the following table.
- K7M engine;
- Gearbox gear - 5;
- Speed 70 km/h;
- Maximum duration - 40 sec.
During this test, the ECU prohibits purging of the adsorber and issues the command "diagnosis of existing sensors".
If, after performing the test, the diagnostic tool has detected a malfunction of the oxygen sensor, see the procedure for processing the DF390 "Oxygen sensor malfunction" fault.
Confirmation of test execution:
- - status ET344 "Oxygen sensor diagnostics results taken into account" has the characteristic "Yes";
- - status ET348 "Oxygen sensor diagnostics performed" has the characteristic "Yes";
- - no faults detected and the on-board diagnostics system warning light is off.
