achieve the proper fuel mix is vital to the effectiveness and efficiency of its 126th Mercedes This article looks at the mixture of control procedures for the early V-8 engine with K-Jetronic fuel injection. Many other European cars of that era followed basically the same way.
for cars with lambda control, it is not possible to set the basic fuel mixture properly, without a properly functioning oxygen sensor. Please see the companion article Mercedes 126 Repair: Finding Vacuum Leaks for more information about this topic. As with the vacuum leak detection procedure, we have our car oxygen sensor is thoroughly warmed up before placing the base mixture. Of course, any vacuum leaks should be eliminated before the mixture can be set.
A little theory
generated by the oxygen sensor voltage is interpreted lambda control unit, which corresponds to the voltage sent to your lambda valve (frequency) of the fuel distributor (FD). Frequency valve is essentially a pulse-style fuel injector - the only such device in the car with continuous injection. This is a controlled "bleed-off" of fuel back into the fuel tank gorivo.Količinu Bled off valve affect the pressure drop across the valve differential pressure within the FD. More fuel from Bled to increase the pressure drop within the FD and increases the flow of fuel to the injectors, richening mixture, the less fuel than Bled reduces pressure drop and leans out the mixture. Fuel is Bled since the frequency of the valve is open, and it occurs when the voltage is nula.Ventil valve is closed when the battery is naponom.Napona of the lambda controller pulses fast and can be fully seen on an oscilloscope. (. This is known as the duty cycle) Fortunately, however, we do not need to see what the frequency range of the valve - and thus, lambda controller -. Make
Soft Practice
diagnostic socket inside the left fender allows us to observe the lambda control in action. When we know the controller is trying to do, we know whether our base mixture too rich or too thin and can be adjusted accordingly. To be specific, voltage pins 2 and 3 diagnostic socket shows the total voltage frequency ventil.Niži voltage can be seen on our voltmeter, more lambda controller tries Richen mixture, ie, to compensate lean condition. The higher the voltage, the more it tries to lean the mixture out.
So what should be the voltage at the diagnostic connector, if the mixture is perfect? There will always be some fluctuation, when the oxygen sensor is hot, the car is in a "closed loop" control, that is constantly responding to motor behavior. But they will be fluctuations in a narrow range around 12.2 to 12.3 volts. (. The exact center point can be found by observing the voltage at the socket when the oxygen termination) exceed the voltage "trip" the 11-volt range indicates a lean condition, the 13-volt range bespeaks a rich condition.
Our response to that intelligence is a very fine mixture adjustment screw controls access to the 3mm Allen key inserted through the tower directly in front of the fuel distributor. Turning clockwise Richens mixture, anti-clockwise naginje.Vijak is extremely sensitive , one only needs to move the turn of the screw at a time. After each adjustment, remove the Allen key (so you do not get stuck when the air flow meter panel rejects) and engine speed. Then recheck the voltage at the outlet. If the voltage stops fluctuating in its entirety, the oxygen sensor is cool and you've gone back to the "open-loop" operation, in which the lambda controller sends a default 50/50 duty cycle. Keep the engine at 2,000 rpm for a time to warm back up sensor.
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