Combustion engines, where the quality of the fuel mixture was adjusted to fixed screw carburetor fading. Today's cars are equipped with automatic control system and control the preparation process of TVS. Electronic unit dispenses the air-fuel ratio after the fuel system actuators. The main quality control of the fuel-air mixture is a lambda probe.
measuring principle
Driver's knowledge of the physical and chemical properties, on which the sensor work is not necessary. But the understanding of the principle, based on a comparison of the content of oxygen ions in the air to the amount of oxygen present in exhaust gases, can help in the analysis and troubleshooting.
The oxygen sensor is located behind the exhaust manifold. High temperatures - approximately 300 degrees, it is optimal for its performance characteristics most reliable for hot gases warm engine.
On the atmospheric side of microscopic channels to the internal electrode supplied with air, oxygen, its content will reference potential. To the outer electrode via holes guard pass exhaust gases, ions, excess oxygen will produce a potential on this electrode. EDS, which appeared as a difference of potentials of the electrodes, and has a measurement signal to the ECU. The value of 0.45 corresponds to a normal content of residual oxygen, 0.2 - mixture of "poor" 0.8 - "rich."
Faults and their effects on engine operation
The effect on engine operation, which has a lambda probe, is particularly evident when the sensor malfunctions. Even an inexperienced driver will pay attention to changes in motor operation:
- there is a warning signal of an engine malfunction;
- Turnover idling spontaneously changed;
- noticeable interruptions when attempting to increase the momentum even well engine is warm;
- Fuel consumption has increased;
- The engine gets very hot;
- the exhaust gases a dark color;
- catalyst quickly clogged.
All this with a high probability can indicate a malfunction of the sensor. But the symptoms are similar problems in the ignition system. To avoid unnecessary actions, pinpoint the source of failures should conduct computer diagnostics.
Using the scanner is easy to determine the source of errors that occur. When the engine is running it is possible to take a snapshot of the parameters. If the signal from the lambda sensor floats, is constantly biased in the zone indicating the overly "Poor" or "rich mixture, this confirms the suspicion of a fault in the sensor circuit oxygen.
Detection and elimination of defects
Visual inspection of the installation site of the sensor can directly lead to the discovery of the cause of malfunction. The most visible mechanical damage. The stone hit the bottom, it may ricochet and damage the outer part of the lambda probe. Such a sensor can not be recovered, it must be replaced.
Broken wires can also cause errors in the training of high-quality fuel assemblies. This reason is particularly critical for the lambda probe with the heating circuits. The signal from the sensor at low temperatures does not correspond to the actual oxygen content in the exhaust.
Factor engine operation may become unstable ingress of exhaust gases into the outer channel of the reference oxygen. Cause - burn-out of the exhaust pipe near the sensor, the destruction of its sealing ring.
Removing the probe, one can detect that the apertures of the shield cup intoxicated combustion products. Exhaust gases are not available for analysis to the outer electrode. Must be cleaned by means of a deposit, wash with petrol and dry.
The sensor can stop working, and exhaustible resources. In this case, the only way out - the replacement.
Visual inspection of the vehicle underbody, exhaust pipe, it is necessary to pay attention to the oxygen sensor. If necessary, make a bandage wires to clean the lambda probe from contamination. This is particularly important for the car after driving on dirt roads, rough terrain.