Toyota Corolla

1992-1998 of release

Repair and operation of the car



Toyota Corolla
+ 1. Maintenance instruction
+ 2. Maintenance
+ 3. Engines
+ 4. Cooling systems, heating
+ 5. Fuel, exhaust systems
- 6. System of decrease in toxicity
   6.1. Specifications
   6.2. Electronic control system
   6.3. Electronic control unit
   + 6.4. System of onboard diagnostics
   - 6.5. Sensors of system of automatic control of the engine
      6.5.1. Sensor of temperature of cooling liquid
      6.5.2. Sensor of concentration of oxygen
      6.5.3. Sensor of an angle of rotation of a butterfly valve (TPS sensor)
      6.5.4. The sensor of absolute pressure on the soaking-up collector (MAR-sensor)
      6.5.5. The air temperature sensor on the soaking-up collector (IAT sensor)
      6.5.6. Temperature sensor of system of recirculation (EGR sensor)
      6.5.7. Car speed sensor (VSS sensor)
      6.5.8. Detonation sensor
      6.5.9. Sensor of an angle of rotation of the crankshaft
   6.6. System of catching of vapors of gasoline
   6.7. System of recirculation (EGR system)
   6.8. System of compulsory ventilation of a case (PCV system)
   6.9. Catalytic converter
+ 7. Transmissions
+ 8. Coupling and half shafts
+ 9. Brake system
+ 10. Suspension bracket and steering
+ 11. Body
+ 12. Electric equipment



6.5.2. Sensor of concentration of oxygen

GENERAL INFORMATION

Sensor of concentration of oxygen

1. The socket of the warmed-up oxygen sensor from the sensor

2. The socket of the warmed-up oxygen sensor from conducting

3. The warmed-up oxygen sensor
Cars are equipped with either one sensor of concentration of oxygen, or two sensors. In system with two sensors of oxygen the main sensor of concentration of oxygen is installed in front of the catalytic converter and traces the content of oxygen in the exhaust gases which are going out of the engine. The auxiliary sensor of concentration of oxygen traces the content of oxygen in exhaust gases after the catalytic converter. The sensor of concentration of oxygen reacts to the content of oxygen in exhaust gases and generates output tension fluctuating from 0,1 B (high content of oxygen, the grown poor mix) to 0,9 B (small content of oxygen, the enriched mix).

The changing output tension from sensors moves on an electronic control unit which defines a ratio of oxygen and fuel in gas mixture. The control unit regulates a ratio of air / fuel in mix by a task of time of an open condition of nozzles. At a ratio of 14,7 parts of air to 1 part of fuel in initial mix the content of harmful substances in exhaust gases minimum, at such ratio the catalytic converter purifies gases with maximum efficiency.

Electronic control unit together with the sensor of oxygen provide maintenance of composition of gas mixture just at the specified level.

If temperature of the sensor of concentration of oxygen is lower than normal working temperature, i.e. it is below 300 °C, then tension on the sensor will be absent. Therefore until the engine does not get warm, on an electronic control unit of a signal from the sensor of oxygen does not arrive and the block works in the mode of the opened cycle.

If after warming up of the engine, or not less than 2 minutes of operation of the engine later, and on the main sensor of concentration of oxygen tension which is not exceeding 0,7 B at a speed of rotation of the engine of 1500 rpm steadily develops, then the electronic control unit will establish a code 21. The code 27 will indicate malfunction of the auxiliary sensor of oxygen.

If the sensor or its chain are faulty, then the electronic control unit works in the mode of the opened cycle, i.e. the block doses fuel according to the programmed value on its entrance, but not according to an oxygen sensor signal.

The correct operation of the sensor depends on four conditions:

      – electric: the low voltage generated by the sensor, very strongly conditions of connections with wires which always have to be pure and strong and is checked first of all, both in case of signals of system of self-diagnostics, and at suspicion for malfunction of the sensor;
      – supply of external air: the sensor is arranged so that air circulates in its internal space. Every time at removal or installation be convinced of purity of air channels of the sensor;
      – working temperature: signals from the sensor do not arrive on an electronic control unit until temperature of the sensor does not reach about 300 °C (this factor should be considered at assessment of serviceability of the sensor);
      – use of unleaded gasoline is an essential condition of the correct operation of the sensor.

Besides the conditions stated above that at service of the sensor it is necessary to follow the following special rules:

      – the flexible conductor and the socket of the sensor of oxygen are non-demountable and are not disconnected from the sensor;
      – damage or a separation of the flexible conductor or the socket can adversely affect serviceability of the sensor;
      – hit of dirt, lubricants and other foreign components on the socket or on the tower isolation center of the sensor is not allowed;
      – it is forbidden to wipe the sensor with all types of cleaners;
      – it is forbidden to drop the sensor or to handle carelessly it;
      – you watch correctness of installation of a silicone cover of the sensor to avoid melting of a cover because of which the failure of the sensor is possible.

Check
PERFORMANCE ORDER
1. For check of the sensor connect the digital voltmeter and on the working engine track indications (the voltmeter has to show tension at the level in volt shares). For this purpose find the socket of the sensor of oxygen and enter the voltmeter probe into contact with a wire of black color from a reverse side of the socket of the sensor.
2. Correctly to connect to a wire of the socket dress on a wire long a straight line shtyrevy a sampler and enter a sampler on a wire into the socket against the stop in metal contact of a wire. Connect the positive probe of the voltmeter to a sampler, and the negative probe with a weight.
3. Start the engine and throughout warming up you watch tension from the main sensor of oxygen (tension has to be at the level of volt shares). The sensor of concentration of oxygen will constantly generate tension signal which on the cold engine (the opened cycle) makes 0,1–0,2 volts. About 2 minutes later the engine will get warm up to the working temperature and tension from the sensor of oxygen will fluctuate ranging from 0,1 to 0,9 volts (the closed engine management cycle joins). If the signal from the sensor of oxygen differs from the specified values, then the sensor is subject to replacement.
4. For access to the socket of the auxiliary sensor of oxygen it is necessary to remove a front seat of the passenger.
5. For check of the auxiliary sensor of oxygen find the socket and perform the same checking procedures as with the main sensor of oxygen.
6. Check a heater of the auxiliary sensor of oxygen (if is available) as follows. Disconnect the socket of the sensor of oxygen and attach an ohmmeter between contacts + B and HT in the socket from the sensor. The indication of an ohmmeter has to be within 11,0–17,0 Ohms.

Prevention

The warmed-up sensor of concentration of oxygen completes only a part of cars. The socket of the warmed-up sensor of oxygen has four contacts.


7. Check oxygen sensor heater supply voltage. At the included ignition (the engine does not work) check presence of tension from the battery between black-red (positive +) and black-blue (negative –) wires in the socket from conducting.
8. On models 1993-1994 of the sensor of oxygen can be checked in a different way. On completely heated-up engine and at the connected sensor of oxygen connect the positive probe of the voltmeter to a conclusion of VF1 of the diagnostic socket (it is specified by an arrow), and the negative probe – to E1 conclusion. Bring speeds of rotation of the engine to 2500 rpm, connect contacts THOSE 1 and E 1 diagnostic socket a wire or an office paper clip.

Prevention

Measure tension only by the arrow voltmeter as it is necessary to watch fluctuations of an arrow.


9. Sustain the engine at a speed of rotation of 2500 rpm for about 2 minutes connect contacts THOSE 1i E1 of the diagnostic socket. Check number of deviations of an arrow in 10 seconds. The quantity of deviations of an arrow has to be not less than 8. If the quantity of deviations of an arrow are less, then warm up the engine once again and repeat check.
10. If quantity of deviations of an arrow still less than 8, then remove the crossing point connecting conclusions THAT 1i E1. Supporting the speed of rotation of the engine of 2500 rpm, measure tension between conclusions of VF1 and E1. If voltage more than 0 V, then replace the sensor of concentration of oxygen. If tension is equal 0, then consider self-diagnostics codes (see subsection 6.4.1) and establish a cause of failure.
11. If codes 21, 25 or 26 are received, then disconnect a vacuum hose of system of compulsory ventilation of a case from a cover of a head of cylinders (see subsection 6.8) and measure tension between VF1 and E1. If tension is equal 0, then replace the sensor. If the measured tension exceeds 0 V, then the engine works with the reenriched mix and repair of a power supply system is required.
12. If other codes are received, then repair the concrete sensor or a chain.

Replacement


Prevention

When cooling the final collector or an exhaust pipe in which will screw the sensor contract therefore, on the cold engine it is difficult to unscrew the sensor. Not to damage the sensor (it is supposed that you will use it further) start and warm up the engine within 1–2 minutes, stop the engine. Be careful not to get burns when performing of the actions described below.


PERFORMANCE ORDER
1. Disconnect the rechargeable battery from weight.
2. Lift the car and establish on supports.
3. Accurately disconnect the socket from conducting of the sensor.
4. Turn out the sensor of concentration of oxygen from an exhaust pipe (on a photo the special extended face head facilitating a sensor otvorachivaniye is represented).


Prevention

Not to strip a thread of the sensor do not make too big effort at an otvorachivaniye.

The sensor of oxygen can be screwed in a final collector or fasten two bolts.


5. For simplification of the next removal of the sensor it is necessary to use structure against a carving holding strap. The structure is always applied on a carving of new sensors, but at removal and the subsequent installation of the sensor which was in operation it is necessary to put structure again.
6. Reliably tighten the sensor.
7. Attach the socket of conducting of the sensor to the main plait of conducting of the engine.
8. Lower the car and attach the rechargeable battery to weight.



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