I will not mention precisely which of two BMW authorized service centers these “diagnostics” was performed. There are several reasons. First – let’s be honest; some kind of revenge on the car owner can follow. And to me also. The second – is the technical/knowledge level in both companies, unfortunately, is similarly sad; accordingly – this story can be on any of them. The purpose of this entry – to the owners of vehicles: evaluate the results of the diagnostics critically, even if it is performed by such authoritative specialists as BMW representatives. I have lost hopes that the situation will get better because already, for years, the attitude of the management of the local BMW representatives is – we don’t need to raise qualifications because everything is good as it is; we don’t need to educate our employees, because – who will question our competence, even if we will be wrong. The customer pays for every spare part and movement, so – why bother?
I will still (again and again) allow myself to question your competence, gentleman.
But now – I’m moving to the technical outline of the problem. The over of car with N43 petrol engine approached me with claims that the car is performing very poorly. Misfires; shivering; increased fuel consumption; vibration; the engine regularly runs on 3 or even 2 cylinders. Diagnostic, performed in the authorized service, was adamant: all injectors should be replaced! The representative of the BMW drew up an estimate (the owner of the car showed it to me, accordingly – this is not the defamation campaign), in which it was written that the replacement of all injectors would cost him around EUR 2000. Before such a significant investment, he decided to hear an alternative opinion. Let’s see the actual situation. Data (including the error messages) were read almost directly after the visit to the authorized service accordingly – we can assume that the situation hasn’t changed fundamentally.

Here are the error message lists:

As we see, there are a lot of problems.
The authorized service hasn’t noticed the problems with the oil pressure; possible issues with the Lambda probe; have not identified performance problems of the cooling blinds or potential issues with the oil level sensor.
In addition, the error message regarding the Lambda probe is recorded 11(!) times during a short period – regarding its performance; 4 times regarding its trim; 3 times regarding system check. Also, the error message regarding oil pressure has already been recorded 2 times after deleting it, and the measured oil pressure at least 5 seconds by row for 2 (times) has been lower than required. Nothing of this was noticed by the BMW service representative? Impressive!

Let’s see live data.
The efficiency of cylinder performance:

The mechanical efficiency of all cylinders at the current moment is correct. Still, the wideband probe of the first bank (marked with red) indicates incorrect voltage (2.95 V, not 2.00 V), which is equivalent to Lambda around 2. For the control, let’s check the Fuel mixture data:

As we see – without surprises. The wideband probe of the first bank really indicates a completely incorrect value. Now there is no slightest doubt – the probe is damaged! Here, the reason for the countless error messages has been identified.

Solution: replacement of the probe.

Checking the data of the NOx sensor:

we see:
a. good news – the sensor has reached Online mode; its Lambda indications are more or less correct;
b. bad news – even in Homogeneous mode, the NOx concentration in the exhaust is high, a logical assumption – the cell of the NOx sensor is clogged, and the actual Offset value – enormously increased. Yes, there are no error messages regarding the NOx system, but the only reason they are not present – severe problems with the Lambda probe. As soon as DME identifies these problems, it stops the performance tests of the NOx system.

Let’s check the actual data of the injectors.

Homogeneous mode:

And – Stratified charge:

All injector data looks good! At least at the last time, when DME was performing the injector measurements, everything was excellent! Why has the authorized service representative “charged” the owner of the vehicle EUR 2000? Complete incompetence?

During the repair:
a. the wideband probe of the first bank was replaced;
b. the NOx emulator was installed;
c. necessary service procedures were performed (re-adaptation of the engine).
After repair – vibrations, misfires, and shivering have disappeared. The engine uses a Stratified charge, and the fuel consumption has been reduced. Of course, at the next step, other problems should be checked – oil pressure; cooling blinds.

Here is injector data after repair:

Injector data looks excellent! I will not burden you with other data – they look perfect.
Here is the video of the cold start, print screens:

Around 40 seconds after the start, the wideband probes are activated, and, as we see, the fuel mixture is perfect!

Also, the mechanical efficiency of cylinders is perfect!

The data were so perfect that I checked several times if this really was a cold start.

No, everything is fine – the engine’s temperature at the start is 3.8oC.
You can blame anything for the performance of this engine, but the injectors are not the culprit! The injectors are performing perfectly! How so, dear manufacturer’s representative? How did it come?