Oxygen is an essential element for combustion of any type of fuel, including vehicle fuel. The amount of oxygen remaining in the exhaust can be judged by how well the combustion process in engine cylinder fuels is occurring. The lambda probe is used to measure the amount of oxygen. History of the oxygen sensor and lambda probe
History of the oxygen sensor and lambda probe
The practical application of the lambda probe into the exhaust system of the internal combustion engine engineers became interested in the late sixties, and the first serial sensor was created in 1976 by the German company Robert Bosch GmbH. For the first time, Volvo and Saab have used oxygen sensors in their cars. The second name of the lambda probe is from the Greek letter "Lambda". In the engine theory, this letter is used to indicate an excess air ratio in the fuel-air mixture.
How the sensor is performed
The lambda probe signal is used by the control unit to maintain the optimum or, as it is called in the automotive, stoichiometric air to petrol ratio in the combustion chamber. The ratio of about 14.7:1, where 14.7 is the amount of air needed for the most efficient combustion of fuel, is considered to be close to ideal.
The lambda probe is applied not only to motor vehicles but also to other fuel combustion devices such as water boilers. As with the LAN, it is used for configuration
The oxygen sensor is installed in the outlet of the exhaust manifold. If a secondary lambda probe is provided in the design, the secondary lambda is wound up in the opening in front of the catalyst. The operation of the lambda probe is based on the principle of the German scientist, Walter Nernst, who discovered the possibility of discovering the normal potential of the electrode with the help of oxygen. If this principle is considered for the lambda probe, the amount of oxygen in the exhaust may be determined by means of the electrodes that are in the sensor.
The effective operation of a lambda probe can be achieved only at a temperature of not less than 300 degrees. So the lambda is equipped with an electrical heating coil that creates the desired temperature condition until the engine is warm. The oxygen sensor shall be positioned in the exhaust stream so that the external electrode is washed by the gases, while the internal electrode is in the ambient air. Depending on the difference in the amount of oxygen between internal and external electrodes, an electric charge is generated with a maximum power of 1 Volt. The resulting value shall be transmitted and processed in the engine control computer. The signal from the unit is fed to the fuel injectors. The amount of petrol in the air mixture may be increased or reduced, depending on the signal being given by the control unit.
Lambda Probes Types
You can often hear the phrase "broadband lambda probe". Any driver, infatted by a tuning engine, will sooner or later learn the difference between a simple and a broadband oxygen sensor. The main difference between a broadband probe and a normal sensor is the work of a sensitive element. If we speak of the engine's tuning, the signal removed from the broadband sensor is more informative, which is what is necessary in cases where the engine's factory settings are subject to significant changes. The more information you can get from a sensor, the better, since the accuracy of the tuning will depend on it.
Lambda Probes Conditions
The oxygen sensor has a direct influence on the engine, so if the quality of the air is defective, the air mixture may change so sharply that the engine will not be able to operate. In the event of a malfunction, the signal shall be unpredictable or disappears altogether. In order not to complicate the life of the driver, the engine has been designed and introduced to drive the engine and to drive with a faulty lambda probe to the service station. In case of a failure detection, the control unit enters into operation an emergency program that is optimized for different conditions of the fuel-air mixture, allowing it to operate in an average mode. As a rule, in such cases petrol in the mixture is greater than necessary, as it is likely not to die in such a condition.
Broadband lambda-probe allows to observe changes in the composition of the fuel-air mixture in real time
Naturally, the fuel consumption is increased, so that the driver driving an engine running in an emergency mode will sooner or later realize that the failure occurred, even if he did not know it at once.
If the probe is functioning, a number of factors can influence the probe.
First, the location of the sensor in the exhaust manifold shall be of quality compaction. If the lambda probe is not complete, the qualitative measurements should not be calculated. An incorrect wiring of the oxygen sensor is not allowed, because the control unit will assume that the sensor is malformed and will go to the emergency mode. It is not only a lambda probe but also other sensors that cannot be used in any circumstances. Of course, the sensor body is overheated for any reason, for example, when a crack in the exhaust manifold is cracked.
Lambda probe operations
The sensor problems on some engines, mostly obsolete models, may not be recorded by the self-diagnosis program, so if there is a suspicion, it is better to assign a test to specialists. To determine the breakdown of a lambda probe, the experimental bias can be used by a simple voltmeter. Note that the lambda probe is one of the most vulnerable parts of the exhaust system. The service life of the part is usually measured in the mileage category, not the time, and is 40-80 thousand km depending on the condition of the engine, the intake system and the fuel delivery system, and the operating conditions.
