This time, an exclusive case – after the longest while, I inspected the E92 with the N53 series engine in person. When I heard the owner’s story, I could not remain indifferent.
More than 3 months ago, a nice E92 coupe, which (as I understood from the EU4 label) arrived from Germany, was sold here, in Latvia. As I understood from the owner, the seller offered the warranty – say, if there are any issues, we will solve them. Problems with the engine (vibrations, misfires, Check Engine in COMBI) started the following day after purchase. So the seller has been “solving” the problem for already 3 months now. The car has visited “several diagnostics” specialists, the mechanic of the seller also got in touch with me. When I asked to send the diagnostics data, he promised to do it, but… Disappeared.
When the buyer’s patience was over, the car was taken from the seller’s “service”, and I had the option to evaluate its technical condition. I would like to add that I only assessed the state of the engine because it’s the most critical part for now. In my opinion, the car can not be used normally – quite a powerful argument.
I started the inspection with the most straightforward part – the error message list.

Here is the problem with a water pump. With the reference position of the exhaust VANOS. Damaged NOx sensor. I’ll add right away – I don’t like what I see because, in this case, we are not talking only about a leaking injector. Several simple problems have not been solved!
I open the Info list, and… What’s that?

How so? Not available? I know only one reason why the Info list is not available – the software has been “upgraded”. The “upgrade” typically aims to hide some specific error messages.
I have no doubt left when opening the History list – the error messages have been hidden. Here is the list of the error messages which are not “recognized” by the DME.

What kind of error messages are the “upgraders” typically hiding? Usually, the most expensive problems, for example, regarding the NOx system and the CO catalytic converters, are hidden. The CO catalytic converters are a separate story. Still, the exhaust has been “upgraded”, giving away a specific sound in the location of the NOx catalytic converter when the engine warmed up. Yes, true “specialists” have been “repairing” this car.
Outside temperature around +5oC. Cylinder No.5 has been turned off. The engine runs on 5 cylinders. It is confirmed by Rough run data and also live data of the injectors.

Turned off cylinder: marked. Pay attention – 2-nd management impulse of the injectors left is minimal – 0.2 ms (200 us).

At the same time – in both (!) banks, the fuel mixture is extremely rich. It is clear that at least 2 injectors are leaking in the second bank – so roughly that even with one cylinder turned off, the fuel mixture is rich.

As we see, the fuel mixture of both banks is rich (Lambda 0.97), not taking into account the Integrators, which are below -25%! The injectors are leaking at least double the amount (in the second bank – even four times more)! Also, Offset type LTFT are negative for both banks accordingly – DME doesn’t have any wide options left to fix the situation.

When the engine is half-warm, the injection of cylinder No.4 in the second bank is confirmed as leaking one (more precisely – leaks more than the other two in this bank). But I have big suspicions that this is not the only leaking injector of this bank.

The injector of cylinder No.2 leaks the most in the first bank, but it looks like the other two are not even close to the acceptable technical condition.
It does not make sense to check the injector adaptation data – they are ancient and, accordingly, irrelevant. The engine hasn’t worked in Stratified charge for a long time now – both “thanks” to the “upgraded” software and problems with the NOx sensor. In Homogeneous mode, it wasn’t working in the correct thermal segment because the electrically managed water pump hasn’t been electrically manageable for a long time now.
The data of the NOx sensor confirm that there is no even Offset value confirmed for it. Obviously, the sensor hasn’t reported correct Online data for a long time now:

Yes, DME has identified serious problems with the fuel mixture and the “health” of the injectors:

Here, colored learnbits, which should be colored in “opposite”. Unfortunately, “thanks” to the range of problems – damaged NOx system; damaged water pump; damaged VANS; leaking injectors – DME cannot fix the situation.

After inspecting the ignition coils, I have to conclude that the Delphi (worst choice) ignition coils have been replaced at different times. Some are in poor technical condition, with clearly visible signs of current leakages. Such injectors should be replaced immediately.
The injectors – the actual 11th release (true though, the injector of the 11th release have been available for many years now, accordingly – it is not the confirmation that the injectors have been replaced recently).
What could be the reason for the leaking of so many injectors? My experience says – most probably, someone has added some “cleaning” additive to the fuel. This is a typical try of the “repair” when the engine starts to vibrate or shiver. This engine was vibrating and shivering because its NOx system was damaged, and no measurements of the injectors (and adaptations) were done.
During diagnostics, I also checked the performance of the VANOS. Here are some screenshots from a short video:

As we see, the exhaust VANOS cannot follow the required position. The situation with the intake VANOS is only slightly better. What happened to the VANOS. The regulation valves have clogged. The cause is long oil change intervals and an incorrect driving profile (city traffic).
Unfortunately, the car is in very sad technical condition. It hasn’t been correctly maintained (not even about repairs) for a long time.
Solution of the injector problem: cleaning the fuel system and replacing the injectors. Yes, during the first step, only the mainly leaking injectors could be replaced; then restore the NOx system; then gather data regarding other injectors. Then replace all leaking injectors, etc. But in this case, it looks like at least 3 .. 4 injectors should be replaced in the first stage. In addition, it is still warm outside; what will happen when the temperature goes down? Without any illusions – all other injectors will have to be also replaced.
Solution of the VANOS problem: cleaning the oiling system and replacing the valves.
Repair of the NOx system: installation of the emulator (I don’t believe that someone will be ready to replace the entire NOx system – then the repairs would cost around EUR 2500).
At least half of the ignition coils should be replaced. Shortly the mechanic will check the spark plugs; good news – even in the worst scenario, replacing all spark plugs will increase the total repair expenses by around EUR 100.
It is very plausible that the CO catalytic converters were destroyed a long time ago and all previously mentioned. Unfortunately, these engines have no alternative; only OEM catalytic converters can be used. The costs of the catalytic converters (together with Lambda probes) are around EUR 2000.
The stock software of the DME should be restored.
The water pump should be replaced immediately.
Harsh, but the repair of this engine can cost around EUR 5000, if not even more. I don’t think the buyer was considering such a scenario.

The morality of this entry:
a. Remember – the miracles don’t happen! If the current models on the price cost at least 30 .. 50% more than in the local car reseller, you have to understand that these cars will not be in perfect technical order! Yes, an expensive car does not guarantee a perfect technical condition o the car, but a cheap car will not be cheap and perfect at the same time!
b. if you don’t have a considerable financial “cushion”, don’t buy BMW with N43/N53 and similar DI petrol engines! These engines are expensive in terms of repairs and maintenance!
d. pay double attention if you don’t have high-quality pre-purchase diagnostics available! If you don’t perform pre-purchase diagnostics in detail, be ready for such “surprises”;
d. if you purchase the car from a legal person in the “developed EU”, you have a month to return the vehicle to the seller if some hidden defects (not mentioned in the sales agreement) surface. This car has many flaws; if all of them were counted in the sales agreement – I doubt the buyer would purchase it. Instead, if you are buying such a car from a local “presentable reseller”, you can expect problems because here, in Latvia, the sellers (legal persons) don’t offer a return. In the best case, the seller provides a “warranty”, which does not work in real life, as you see in this case.