More and more owners of cars with N43/N53 series engines know that their vehicles can work in Stratified charge mode.
What is the specialty of Stratified charge mode, you can read in our blog, but in this entry:
More in details about INPA menu ../F9/F1
Many N43/N53 owners desire to see this menu in such form:
Such menu means:
- required injection mode of DME: Stratified charge;
- maintained injection mode of DME: Stratified charge.
Many readers of the blog are sending the emails with an identical message: when pressing the key F3, the Stratified charge is not turned on. Obviously, the engine has some problems.
No, it’s not true! More precisely – yes, the engine may have some problems, but – this obstacle is not a confirmation for it.
Menu ../F9/F1 IS NOT a menu to forced TURN ON the fuel injection mode. This menu is designed to FORBID the fuel injection modes. So:
- if you press key F1, only Homogeneous injection mode will be allowed;
- if you will press key F2, only Homogeneous and Homogeneous lean injection modes will be enabled;
- if you will press key F3, Homogeneous, Homogeneous lean, and Stratified charge injection modes will be allowed.
Which mode to use in the current conditions – if will be chosen by DME itself (of course, taking into account your prohibitions).
The homogeneous fuel injection mode can not be prohibited: it is a “basis” mode, in which the engine runs while it’s cold; when it has some problems due to which it can not use the fuel-saving Stratified charge injection mode. These “additional” modes (Homogeneous lean and Stratified charge), in turn, can be prohibited.
Why these injection modes should be prohibited? Sometimes such a prohibition can be used to evaluate the performance of the engine precisely in Homogeneous and/or Homogeneous lean modes. For example – if the misfires in Stratified charge mode are observed. If the engine strongly shivers in Stratified charge mode, it can be forcibly switched (pressing F1) to Homogeneous mode and continue testing. Fundamentally different fuel injection conditions allow identifying the causes of the misfires very quickly.
The most important – as many other menus, also this menu is intended for the development engineers of the car during testing stages of DME and the engine. When the vehicle is on regular use, there is no need to limit its functionality. Even more – if the Stratified charge will be switched off (prohibited), the car will experience all problems (vibration, shivering, increased fuel consumption, damages of the exhaust system, etc.), which are typical for a damaged NOx system.
Note: the functionality limitations also remain for the future driving sessions (even if the car was “put to sleep”). Remember it! Always when exiting this menu, press F3 (allow the DME to use all three injection modes) of F5 (stopping all manual limitations)!
In conclusion: in the blog, you can read in detail, in which cases DME chooses a Stratified charge and when it is not used. Very shortly – DME IS NOT using Stratified charge:
- for the cold engine;
- on high loads, not depending on the temperature;
- if there are any problems with the NOx system (defect of the NOx system, contaminated NOx catalytic converter or its performance is insufficient);
- issues with CO catalytic converters;
- uneven performance (misfires);
- damages of all systems (for example: VANOS, oil pressure, HPFP, leaking of the injectors, etc.).
DME can switch off a Stratified charge if some service procedures are performed (measuring of the injectors; trim of the wideband Lambda probes, throttle adaptations, etc.).
In idle, DME can use both Homogeneous mods and Stratified charge – depending on the driving history, exhaust temperature, etc.
Note: for the F series vehicles, which are equipped with N53 series engines, can have hidden problems (contaminated NOx converter; misfires; issues with the CO catalytic converters, injector adaptations, etc.), but there will be no error messages recorded. At the same time – due to these hidden problems, a Stratified charge will be prohibited.
The fact is the Stratified charge turned on or off, has to be evaluated on the go, driving evenly with speed 60 .. 100 km/h. More about the testing of the Stratified charge read here: