In this entry, I will describe an example of how to act if the situation is worse than usual. Typically, I suggest – evaluating the injector adaptation data, Rough run data, and other information available.
But what do you do if a cylinder stubbornly refuses to work? When DME sees the group misfires, it switches off the current cylinder. Replacing the ignition coil and spark plug does not help. Obviously, there is a problem within the injector itself (of course, the compression should be checked – mechanical damage, but such a possibility is very, very low). But the main question is – is the injector of the switched-off cylinder the actual culprit, or maybe the injector of some other cylinder?
A typical situation is that injector X is leaking, but the misfires are starting to appear in some other cylinder Y (Z) of the same bank. The fight for the “health” of cylinder Y (Z) does not help in any way because the actual problem is in a completely different place. Why did the misfires start in another cylinder?
a. if the injector of cylinder X is leaking, DME sees a rich fuel mixture in the exact/whole bank and reduces the fuel amount injected by all cylinders (X; Y or X; Y, Z);
b. the fuel mixture in the cylinder – culprit X becomes more correct; it’s good. At the same time, in cylinders Y and Z, the fuel mixture becomes lean;
c. a rich fuel mixture ignites well, and cylinder X performs without any problems. A lean fuel mixture ignites much worse, so misfires appear in cylinders Y or Z (or even in both of them: Y and Z).
This nuance is finally mentioned in the newest versions of ISTA in the description of the performance of these DI engines.
This time – a slightly different example.
Patient: E60 with N53. The owner chose to install the NOXEM. We can guess that the car had some troubles – not without the reason the owner decided to invest in the repair. The History error message list indicates that cylinder No.1 has been switched off on a regular basis. For example:
There was a hope that after restoring the Stratified charge, DME would measure all injectors again, and the problem would disappear. Or, in the worst case – there will be injector data, which would show the direction, which is the damaged injector.
The problems started directly after deleting the adaptation. Even a desperate fight (numerous engine restarts, warming up, driving sessions, etc.) finished like this:
As we can see, DME is stuck in the first step of the adaptation creation – it tries to adapt the fuel mixture of the banks in the Homogenous mode (the black learnbit). All other (6 pcs, white coloured) learnbits – these adaptations are not completed. Accordingly – there are no injector data. In any of the injection methods.
The overall/bank fuel mixture:
As we can see, both banks are working in an open loop! In addition, Lambda in both banks is entirely incorrect!
NOXEM confirms the readings of the wideband probes – the average Lambda is around 1.35. Around 35% air leftover!
Yes, the injector live data confirms that the injector of cylinder No.1 is switched off again (and the restart of the engine does not help. 29CD confirms what we see in the live data). Rough run data are unclear – there is chaos in both banks! What to do?
What should be done in such cases:
a. first, delete all old adaptations. Make sure that the flywheel adaptation learnbit in ../F5/F7 menu is white (it confirms that all adaptations are deleted);
b. start the engine. The first start (with an unadapted flywheel) after deleting the adaptations will be an open loop without any attempts to correct the fuel mixture (with unheated probes);
c. observe the Rough run data. Yes, a certain permanent vibration is possible (the injectors are not measured, and the fuel mixture is not corrected). Still, the engine should be able to work on all (4 or, in this case, 6) cylinders;
If any of the cylinders are not working (and the replacement of the ignition components is not helping) – obviously, the injector of this cylinder is leaking very strongly. It is so strong that the spark plug is flooded. Or – its beam is wholly incorrect and hits the spark plug directly. Finally – it is possible that it is not injecting but flooding the fuel.
In this case, cylinder No.1 ultimately refused to work. Its mechanical efficiency was 0; after a moment, the error message 29CD appeared in the DME error message memory. There is no doubt – in this case, exactly the injector of this cylinder is the culprit.
After the installation of a new injector, the situation changed. Here is what the Rough run data in the open loop mode looks like (adaptations deleted just now):
Not taking into account that the car has injectors of different releases/production dates installed:
a. cylinder No.1: 11th release, 02.2024. (new injector, purchased from the BMW dealer);
b. cylinder No.2: 11th release, 07.2015.;
c. cylinder No.3: 08th release, 06.2010.;
d. cylinder No.4: 11th release, 07.2015.;
e. cylinder No.5: 09th release, 07.2011.;
f. cylinder No.6: 08th release, 06.2010.
Rough run data look very correct! The engine runs on all 6 cylinders, without vibration that could be sensed.
After creating the initial adaptation (they were created during some 10 .. 15 minutes):
As we can see, all initial adaptations are successfully completed!
Here, the injector adaptation test in Homogenous mode. Everything looks perfect!
And here – injector adaptations for Stratified charge/idle:
Excellent result!
Here we see an increased flowrate adaptation value (for Stratified charge/partial load) exactly for this injector of the 1st cylinder. How so? The explanation is simple – the beam and atomisation of this injector are perfect. The efficiency is higher than one of the injectors, used for 10+ years and longer. So, it is only self-explanatory that this injector should be “slowed down” a bit.
Self-explanatory – all basic data of the adaptation, and LTFT of the banks are correct, and no fuel-related or misfire-related error messages in the DME error message memory. Subjectively, the engine runs perfectly.
This is an example that even with the injector of different releases and their being of a reputable age (some – 15 years), it is not an obstacle to the correct performance of the injector/engine.