Sonda lambda universala, cu 4 Fire

SONDA LAMBDA UNIVERSALA (MAGNETTI MARELLI)
4 fire

Nr. de folosinta:�SLP4108

Catalog si MANUAL UTILIZARE aici

ECHIVALENT CU�0258986504

OZA624-E4

1.997.004

10.7003

000-053

000-093

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Lambda sensor, also called oxygen sensor, is designed to measure the amount of oxygen in the exhaust. As long as the engine supplysystem, as well as systems responsible for the exhaust emission and abstraction, are efficient, it can be assumed that the amount ofoxygen in exhaust gas results from the composition of the mixture in the cylinder. In this case ECU that controls the injection system useslambda sensor signals to correct the mixture composition through the extension or reduction of the injection time. The lambda sensor\'smost important task is to prepare the mixture so that the exhaust gas that is being generated would have the composition providing theoptimal catalytic converter operation.Lambda sensors used by car producers can be of different constructions and can work according to different operating principles.However, about 90% of them constitute zirconia dioxide sensors. The principle of the operation and selection of the aforementionedsensors is described below.The engine ECU uses the information from the lambda sensor.When the lambda sensor signal is found reliable, the ECU stillmakes an attempt to lengthen the injection time if the informationfrom the sensor indicates that the mixture is not thick enough orreduces the injection time when the information indicates that themixture is rich enough. This operating principle results in acontinuous change of the lambda sensor signal during theoperation of all the systems. The fluctuation of the lambda sensorsignal voltage over time is similar to sinusoid.The frequency of changes can constitute the basis of theestimation of both the sensor efficiency and the efficiency of thewhole system. Generally, the higher the frequency the better. Anexception to the rule consists in when the lambda sensors areassembled in OBD/EOBD systems, behind the catalytic converter.The sensors\' signal is usually continuous and it is used for catalyticconverter diagnosis.Increased fuel consumption, irregular vehicle acceleration, the lack of lambda sensor signal changes while the other systems areefficient, as well as an error code obtained as a result of supply system diagnosing that informs us of the inefficiency of the lambdasensor, should give us an indication as to any faults to be checked in the lambda sensor operation. It is worth using Magneti Marellistimulator tester of the lambda sensor (ref. No. 007935908000) to confirm the diagnosis.When requiring a replacement of the lambda sensor, it is best to use the sensor destined for the given car ( please refer to theMagneti Marelli lambda sensors catalogue). The sensor is characterized by respective parameters and the correct plug guaranteesa correct sensor electric connection.Zirconia dioxide lambda sensor works as the current generator. The warm-up of theceramic measuring element to the temperature of 400 �C enables the oxygen ions to flowfrom the air to the exhaust pipe. The amount of ions that will flow to the exhaust pipe dependson the difference of concentration of the oxygen ions both in the air and in the exhaust pipe.If the mixture that is being burned is rich, there is a low amount of oxygen ions in the exhaustgas, the considerable difference in concentrations occurs and the flow of ions to the exhaustpipe is high. As a result, the high voltage close to 0,9V is obtained.If the burning mixture is lean, there is a considerable amount of oxygen ions in the exhaustgas, a small difference in concentration occurs and the flow of ions to the exhaust pipe is low.As a result, the low voltage close to 0,1V is obtained.The older types of lambda sensors were thesensors which obtained the operation temperatureas a result of heating up due to flowing exhaust gas.In order to reduce the warm-up time, producersequipped the sensors with heaters. Taking intoaccount older cars, there are usually heaters oflower power installed. To avoid overloading thevehicle\'s electric system, the heating element oflambda sensor increases its resistance along withthe temperature growth. During lambda sensorsoperation it was observed that the mass of lambdasensor that was screwed into the rusty exhaustpipe differs from the mass of the vehicle. Inaddition, a short-circuit to the mass of the signalwire was interpreted as a thin mixture signal. Dueto the aforementioned, the producers were forcedto separate the sensor “mass” wire from thehousing mass.