This time, the owner of BMW with N52 approached me. He is from the “Large Neighbor”. From country, where the exhaust measurements are practically not measured during TI (emission tests of EU 4 are counted as for EU 2, and as I guess, in many provincial TI stations, even such check is not done). In this country, it is prevalent to “transform” the car to EU 2. CO catalytic converters are cut out; control probes are “amputated”. 

There are several causes for such barbaric methods. First – the poor fuel quality, which damages CO catalytic converters. Second and main – very low solvency of the car owners, there is not enough money for a proper repair of the car. Third – very low qualification of service specialists; no spare parts are available; the existing “specialists” are custom with Lada & Moskcvich level problems. Most problems are solved with “left” methods. This country is Russian Federation.

The owner of the current car has only one little problem: fuel consumption.

The average consumption on the highway is around 17l/100km, in the city traffic: 21l/100km and even more. How would that be possible?

The owner of the car sent the diagnostics data. First signs that something is not quite ok:

I wonder why the Nernst parameter (internal resistance) of the Control probe is incorrect? As if the probes are not connected. Or DME does not even try to warm them up!

Indeed! DME controls the connection of these probes but does not warm them up. ADC measures the inlet voltage of these probes, but we see that (logically) the probes are not warmed up – they are not working!

The owner confirmed that the engine has been “rebuilt” to fit the EU 2 exhaust norms. The CO catalytic converter is removed, control probes and the DME software is “upgraded”.

Why did he do that? Because everyone is doing it!

Here, the consequences of the “upgraded” software:

The data of cylinder mechanical efficiency in idle indicate that

a. 3-rd cylinder is “lazy”, it efficiency is -10%;

b. cylinders No.2 and No.5 are too active, their efficiency at least +12%.

So, the difference in cylinder performance is around 20 .. 25%. It is a complete crash!

Strange that the car owner does not mention that a strong permanent vibration can be felt in idle. Obviously, all BMW, after such an “upgrade”, perform the same way, and it, obviously, counts as normal.

These data mean – even in the case of a perfect fuel mixture, the fourth part of the fuel is spit in the exhaust, then, with a pungent stench, get in “air”.

Let’s see the fuel mixture data:

The fuel mixture in both banks is rich, in the 2-nd bank reaching even 0.96 .. 0.97.

Yes, also here we see – the fuel mixture in both banks is rich. DME considers that but does not even try to fix it? Yes, DME software really is “upgraded”!

As we see, DME itself indicates that at least 25 .. 30% of the fuel is thrown in the exhaust. And it is only idle!

But, even if the DME would work “by the best conscience”, the result would be unpredictable. The point is that control probes also perform the main trim of the (wideband) probes. Without this operation, wideband probes work very inaccurately! The current DME can even “think” that Lambda is perfect (1.00), but in reality, it could be 0.90 .. 1.10, and even more inaccurate! More about this problem I have written here.

In addition, no one has even the slightest idea, how other systems, for example, VANOS, of such “upgraded” DME works. How the automatic transmission switches gears. Clearly, DME works in complete limp mode; logically – other systems are switched to work in alternative (emergency) modes. 

Unfortunately, I was not able to help the owner of the car. The only suggestion – do not to perform such “upgrades”. The BMW employees are not idiots, and there are no unnecessary details!