Documentation on disabling the lambda probe, lambda-free firmware and chip tuning for BMW, option without catalyst
BMW has a huge team of talented people. They are an order of magnitude smarter than our garage technicians. From their engines they achieved a compromise between power, fuel consumption and service life. They care about the future, which is why they comply with EURO environmental standards. BMW cars with a gasoline engine, and later a diesel one, are equipped with a lambda probe, a catalyst and ventilation of the fuel tank by burning the vapors rather than releasing them into the atmosphere. These expensive components affect the price of the finished car, but will allow our children to breathe without a gas mask.
But in the 90s, there were countries that had less stringent standards for the environmental friendliness of automobile exhausts. For example, Gulf countries, option L822A. In them it was possible to order a BMW car without a lambda probe, catalyst and fuel tank ventilation — option S199A. The price of the finished car was reduced by the price of these expensive components.
We immediately need to debunk the myth: “I have the catalyst cut out, which means the lambda probe is no longer needed.” On the one hand, a lambda probe is needed for the catalyst to operate effectively in exhaust gas neutralization. But even in the absence of a catalytic converter, the lambda probe continues to constantly adapt the engine (fuel mixture) to the environment, wear and tear and minor breakdowns of the engine itself. Why remove your own gas analyzer from the engine?
It should also be noted that almost any DME ECU firmware (with the exception of MS40.0) with a lambda probe has a lambda-free operating mode. Read. That is, to switch the engine to operating mode without a lambda probe, it is enough to disconnect the chip from the sensor (semit a malfunction of the lambda probe). A fully serviceable engine will not work worse because of this, it is in good working order and does not require correction of the fuel mixture from the lambda probe. If after disconnecting the lambda probe the engine runs like shit — that means he is shit, and the lambda probe somehow allows him to still work.
Why then do you need lambda-free firmware if you can simply disconnect the sensor connector?
Read. Without a lambda probe, the engine does not have the ability to independently adapt to changes in the environment. And any old engines have wear and tear that affects mixture formation. Without a lambda probe, once every six months, or maybe more often, you will have to connect the car to a gas analyzer and adjust the mixture correction using DIS. Without this manual adaptation, over time the engine will begin to perform worse and worse.
Lambda-free firmware only allows you to save the set correction in the DME memory. On DME firmware with a lambda probe, even with the sensor chip disconnected, an attempt to save the correction will end in an error. In fact, this is the only difference between firmware with/without a lambda probe.
Original lambda-free firmware
Disabling the lambda probe only brings more trouble to the BMW owner than simply replacing a non-working sensor. And it doesn’t matter how expensive it is. There is no concept here: “Install the lambda firmware — means forgetting about the lambda probe forever and moving on”.
After coding or programming lambdaless firmware in DME, you need:
- On the engine side, plug the fuel tank ventilation pipe.
- From the fuel tank side, remove the ventilation tube to the atmosphere.
- Install a resistor with number 13901734469 on the connector of the fuel tank ventilation valve. So that DME turns off the fuel tank ventilation and does not change the mixture during the tank ventilation process. Yes, DME compensates for excess fuel vapor in the air-fuel mixture that enters the intake manifold during the fuel tank ventilation process by reducing the opening time of the injectors.
- Connect a gas analyzer to the exhaust pipe and adjust the engine mixture according to the CO level.
Depending on the engine, the mixture correction is set and stored in the DME using DIS, or by rotating a variable resistor in the mass air flow sensor housing.
Now the engine can operate normally without a lambda probe, but the opportunity in the future to diagnose various engine malfunctions based on oxygen sensor readings is lost.
Lambdaless firmware from garage tuners
When starting a conversation about lambda-free firmware, this is usually the method of disabling the lambda probe. The garage master positions himself as 100 times smarter than the entire BMW team, and therefore promises: complete shutdown of the lambda probe, fuel economy, a more responsive gas pedal, increased dynamics, easier engine starting, and so on. An attentive person will notice that this list of promises includes most possible engine problems in order to reach the maximum number of interested people.
Manufacturers of automobile additives promise the same thing: “Fill with our liquid and all your problems with the car, and in your personal life, will disappear.”
These chips are so “cool” that you don’t even need to turn off the fuel tank ventilation and adjust the CO. Everything is tuned specifically for the wear and tear of ALL BMW engines AT ONCE. Only DME will constantly complain about this super firmware and ask to return the original one, but the garage technician knows better. He is such a “cool” master that he doesn’t have time, but most likely the knowledge is to fix it.
In these chips it is impossible to save the CO correction using DIS; the DME software error will always be displayed. Also, these chips do not use the set CO correction value from the variable resistor in the mass air flow sensor. Adaptation of the engine to minor faults and the environment is absent in these chips, which means stable operation of the engine — it's just luck.