Some car owners, for one reason or another, remove the catalytic converter (a simple catalyst). But then they notice that after such "cutting" the car's fuel consumption grows. And not just a few milligrams, but growing specifically, say 10 - 15%, why this happens and what to do with it, let's deal with it.
Cut out the catalyst is a half-way through, you need to set up or sew the car correctly after this operation. Although I do not call on anyone to remove the neutralizer, all this saves our "Mother Nature", and there is a way out about it below.
Why are they removing it?
This is a rhetorical question - there are many reasons. Someone is afraid that the catalyst will fall apart, ceramic sand will get into the engine cylinders, bullies will form, here and to the capital not far away. Someone just already has a huge mileage in the car, and his "wheelchair" is dead - either melted or clogged, etc. Of course, you can put a new one, but it will cost as a "stone bridge", and if you have a used car, say, a 10-year old foreign car, the price of 770 - 1100 USD for the original can throw you into a shock absorber!
And now the catalyst, which goes right behind the engine, that is, it is the exhaust manifold + neutralizer.
It is because of this that they are removed, these are the main two reasons. Remove this is one thing, but competently flashing the car so that it does not spend extra money - this is another.
So why did the consumption grow?
Personally, it seems to me that the reason here is trivial, and it is hidden in the oxygen sensor (it is also called "Lambda-Zond"). In a modern car, there are only two of them, one before the catalyst, the other after. It should be noted that it complies with Euro 4, 5 and 6. EURO 2.3 standards had one before the neutralizer.
The first oxygen sensor (Oxygen Sensor), which goes "up", is needed mainly to adjust the fresh fuel mixture, it measures the oxygen level in the exhaust if it is a lot or little it enriches or impoverishes the mixture.
The second sensor is needed mainly to control the catalyst, i.e. the readings between the first and the second sensor should be different, otherwise, the electronics (in particular ECU) will realize that the neutralizer is not, and will give you CHECK ENGINE, but the machine at all can go into emergency mode.
So the whole point is in the first sensor. It is because of this that the car starts to consume more fuel.
How does it work?
When you knock out the catalyst, the exhaust gases come out of the engine at high speed, go into the empty can of the neutralizer, and nothing keeps them there.
The gas flow is increasing.
The oxygen sensor is calibrated for a certain amount of gases, and now it has increased, so there is more oxygen in them.
Begins to adjust the mixture, adding more fuel, because I repeat, he measures the passage in the mode "online".
This is why fuel consumption increases because there is no obstacle and no back pressure from the hundreds of catalysts.
But this case is not a general practice, someone is fine, on the contrary, after removing, increases power and reduces fuel consumption! So what is the matter?
What to do?
At first, I will say one thing, there is an increase in consumption, only for those who put a deception on the second "Lambda". Here, the firmware remains standard, factory-made, as well as both sensors of oxygen, we simply deceive the second with the help of a special insert. Namely, through the first DC, it increases the flow of gases.
So how to solve the problem. There are only three main ways:
Put a universal catalyst in place. As I wrote from above, this method will be pleasant to many people (here, as they say, ecologists are satisfied - we do not pollute the atmosphere, you are well - it costs a little more than a flame-thrower, and those around us are satisfied - the car does not smell like a "six"). It will create backpressure in the pipe, and thus the amount of oxygen passing near the first DC will be reduced, as a rule, the consumption is normal. It is worth noting that it also needs to be calculated correctly, there are certain volumes of engines, you can weld into the mainline under the car (and not in the "collector"), so, even if it is destroyed, it will not reach the engine. By the way, the price of a universal neutralizer for an ordinary foreign car is about 75 - 100 USD, would you agree cheaply?
Put a flame arrester on. It will also increase back pressure in the pipe, because often the flame arrester has a smaller inner diameter and chambers that "extinguish" the pressure. As a rule, after installation, the flow rate is normalized.
Correct stitching. Usually under "EURO2", here most likely you do not need to deceive the second DC, it is simply turned off. Well and make updating of the first DC. Thus, the new program puts the "brains of the EBU" in order. But it is worth remembering that not all firmware is equally useful, if you sew, then you do it in normal offices.
For those who don't understand what I've written, the video version is clearer there.