E30 series BMW 3
since 1983-1994 of release
Repair and car operation
+ 1. Maintenance instruction
+ 2. Maintenance
+ 3. Engine
+ 4. Cooling system
+ 5. Heating and ventilation
+ 6. Fuel system
- 7. Exhaust system
+ 7.1.2. Exhaust system of cars 318i
- 7.2. System of decrease in toxicity of exhaust gases
7.2.2. Self-diagnostics of system of injection of Motronic
7.2.3. Processor block (ECU block)
7.2.4. Sensors of system of automatic control of the engine
7.2.5. System of compulsory ventilation of a case (PCV system)
7.2.6. Catching system паров gasoline (EVAP system)
7.2.7. Catalytic converter
+ 8. Transmissions
+ 9. Coupling
+ 10. Brake system
+ 11. Running gear
+ 12. Body
+ 13. Electric equipment
+ 14. Good advice
The sensor of temperature of cooling liquid
The sensor represents a termistor (the resistor which size of resistance depends on temperature). In process of reduction of temperature of the sensor its resistance increases and on the contrary.
The sensor of concentration of oxygen in exhaust gases
Socket of the sensor of oxygen
The socket of the sensor of oxygen on models of 325i 1986-88.
The sensor traces the content of oxygen in exhaust gases and generates target tension from 0,1 In (the high content of the oxygen, the grown poor mix) to 0,9 In (the small content of the oxygen, the enriched mix). Changing target tension from sensors moves on the electronic control unit which defines an oxygen and fuel ratio in gas mixture. The control unit regulates an air / fuel ratio in a 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 an initial mix the content of harmful substances in exhaust gases minimum, at such ratio converter clears gases with maximum efficiency. The electronic control unit together with the sensor of oxygen provide maintenance of composition of gas mixture just at the specified level.
Relay of a heater of the sensor of oxygen
If the temperature of the sensor of concentration of oxygen is lower than normal working temperature, i.e. 320 ° With, tension on the sensor is absent. Therefore, until then while the engine will not get warm, on the electronic control unit of a signal from the sensor of oxygen does not arrive and the block works in a mode of the opened cycle (preparing gas mixture automatically).
If after engine warming up, or not less than 2 minutes of operation of the engine, tension later on the sensor not превышаеи 0,45 In at speed of rotation of the engine not less than 1500 rpm, the control unit brings a refusal code in memory.
If the sensor or its chain are faulty, the electronic control unit works in a mode of the opened cycle, i.e. the block doses out fuel according to the programmed value on its entrance, instead of according to a signal of the sensor of oxygen.
The correct operation of the sensor depends on the following conditions:
1. Electric: the low voltage generated by the sensor, very strongly depends on a condition of connections with wires.
2. 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.
3. Working temperature: signals from the sensor do not arrive on the electronic control unit until then while the temperature of the sensor will not reach about 300 ° Page. This factor should be considered at an assessment of serviceability of the sensor.
4. Qualities of gasoline: use of unleaded gasoline is an essential condition of the correct operation of the sensor. Fill the car with only unleaded gasoline.
Besides specified above conditions, at service of the sensor it is necessary to observe the following rules:
1. The flexible conductor and the socket of the sensor of oxygen are not folding and from the sensor are not disconnected. Damage or a separation of the flexible conductor or the socket can negatively affect serviceability of the sensor.
2. It is not allowed hits of dirt, lubricants and other extraneous components on the socket or on a tower insulator of the sensor.
3. It is forbidden to wipe the sensor all types of cleaners.
4. It is forbidden to drop the sensor or carelessly to address with it.
5. Watch correctness of installation of a silicone cover of the sensor to avoid cover melting because of which failure of the sensor is possible.
Purpose of conclusions on the sensor of the content of oxygen
The sensor represents 2 pairs contacts. Idling which one pair is normally closed, and another – is opened. Near complete opening of a zaslonka the second pair of contacts becomes isolated. At the intermediate provision of a zaslonka both pairs contacts are opened. Break in chains or weakening of contacts of the sensor of a butterfly valve can cause spontaneous injection of fuel that is at the bottom of unstable operation of the engine idling.
Measuring instrument of a stream of air
The order of removal and installation is described in subsection 6.4.
Sensors of system of ignition
The procedure for test, removals and installations is described in subsection 220.127.116.11.