In this entry – about an unpleasant symptom, which is familiar for many users of N53. It is known for sure, that the problem is very common for N53 engines, there is no confirmation regarding N43 engines.
Description of the problem:
after starting a cold engine, after approximately 30 .. 40 seconds, it shivers.
This problem can be very well expressed or not so well expressed. If the car starts driving immediately – it hasn’t been observed.
Here, a video, how does the not very expressed example of this problem looks like (46-th second of the video):
The engine shivers in idle, then it continues to work as if “nothing has happened”. Needless to say – no error messages are recorded in the error message memory of the DME.
And now let’s see, what happens with the fuel mixture in the moment of the problem (the video was recorded simultaneously with a previous video):
The only event, which happens in the approximate moment of the hiccup – starting of the heating of the control probes. At the same time – all the time the fuel mixture is correct (Lambda around 1.00), Integrators are stable. Nothing, that would indicate the problem of the fuel mixture of all banks.
To make the situation more interesting:
- there are no error messages at the DME error message memory;
- the engine is re-adapted;
- the engine uses Stratified charge;
- learnbits ../F5/Shift+F6/F2 indicate correctly finished adaptations;
- the temperature-depending adaptations of banks ../F5/Shift+F5/F4 – correct;
- permanent vibration is not observed, Rough run ../F5/F7 indicates correct mechanical efficiency of cylinders, so – also the fuel mixture of each cylinder is correct;
- both offset type and multiple type LTFT – correct.
Also, adaptations of all connected systems – throttle, Tank ventilation valve, EGR – are correct.
Mass misfires for the engine are not observed, this hiccup happens only once, in a certain time since starting the engine.
I have no smallest doubt – this is a software bug. One of many. It’s sad, but this situation can not be fixed correctly, because the latest software releases for MSD80/81 are dated around 8 years ago.
Cases, when such, also – strong, hiccups could be justified (refers also to N43):
- problems with oil pressure: if DME detects the inability to maintain the required oil pressure appropriately long (several seconds), the emergency mode is turned on. In this mode, the oil pump maintains the max oil pressure until the next driving session. At the moment, when the emergency mode is turned on, a strong hiccup happens; DME records the error message regarding oil pressure (static);
- problems with fuel pressure. If HPFP is unable to maintain the required pressure for a longer time (5+ seconds), it is disconnected. Switching to the emergency mode with the pressure of 5 Bar (ensured by LPFP), hiccup will be felt. DME will record the error message regarding HPFP pressure (static);
- problems with SOC/SOH data of the battery. If the battery is not registered correctly after replacement or is not registered at all, SOH of IBS system indicates a negative value – IBS system don’t work correctly; regular hiccups can appear because of the management algorithms of the alternator are failing and the onboard value sometimes drops below the allowed limit;
- several reasons (for example, a complete crash of the system due to some leaking injector, HPFP overpressure valve problems and other defects), which cause the Internal reset of the DME. This error message is recorded only in the Info list and is seen only with INPA (..F4/F2/F3). In this case, will be completely incorrect fuel mixture at the moment of shivering, usually, the error messages are recorded, for example, regarding HPFP – drop of the pressure or plausibility (also these error messages can be recorded directly/only in the Info list).
