Stratified charge. Idle. Part 2


First part regarding the performance of N43/N53 engines in idle you can read here.

This time – more about the Stratified charge, because data of cylinder-individual correction in Homogeneous mixture mode, unfortunately, are not available. Accordingly – in case of any problems, we have to investigate, how the engine behaves in Stratified charge mode.


Information regarding Stratified charge in idle are available here: ../F5/Shift + F6/F5.

First three lines – existing reference values, next three lines – momentous values of applied corrections.

Reference values – values, with which the engine start next Stratified charge cycle.

Momentous values – if the engine works in Stratified charge (idle), evening the idle, fuel amount correction of each cylinder is changed, to prevent any, even the smallest unevenness. After some time (typically – several times a minute), if new (different from previous) balance of the perfect corrections is reached, reference values are being overwritten.


Unfortunately also this, as if as simple as this algorithm, has specific nuances. Possible scenarios:


1. The engine works in idle, in Stratified charge, actual corrections are changing after a little while (typically – once in 1 .. 15 seconds). This mode means – the engine actively smooths out the evenness of the engine – everything is OK: reference data are “fresh”, parameters or injectors and other conditions of the engine performance after the previous cycle/existing cycle of Stratified charge are not changed significantly. The engine “feels comfortable”, MSD80 provides the best possible idle.

2. The engine works in idle, in Stratified charge, but actual corrections are not changing for a long while. Of course, the ideal scenario also can be possible, when the idle is balanced perfectly and the engine runs so smooth, that nothing has to be corrected. But usually, it does not.

Quick control of the situation ../F5/F7

If the indications of all cylinders regularly are changing the “polarity” – obviously, the engine applies new/different corrections, but they are not (yet) displayed. New (changed) actual and reference values of corrections will be displayed after a moment (after “confirmation”).

Note – it does not matter, how large difference from 0 the bar of the cylinder are displaying – different SW releases have a very different sensitivity to Rough run. The main sign of smoothed out idle – cylinder efficiency indications are changing “polarity” (of course, if the engine works evenly, without shivering – misfires; data are fluctuating around 0 value, not displaying large differences after a moment).


If Rough run data are displaying permanent disbalance, most probable cause of the problem – the existing situation is significantly different from reference values, therefore MSD80 don’t apply necessary corrections. Exact requirements for confirmation of new corrections are not known (because no source code of the software is available) – they can be different: both by timer and number of cycles, etc. Experimentally identified, that, for example, when the new driving session is started, the allowed corridor of differences of old applied and new necessary corrections is much wider, it means:

starting a new session, even in the case, if significantly changed corrections are necessary – they (new corrections) are applied immediately (idle is even, Rough run data confirm it) but: these values are not displayed for some time, and also new reference values are not confirmed for a long while.


What circumstances can cause such problem?

1. Of course, strong “floating” of injector parameters. If possible, observe applied corrections. If for any of injectors it radically changes, when other obstacles (temperature of the engine, load in idle etc) are not changing, it must be paid attention to it (has to be cleaned or replaced).

2. The second group of circumstances – change of engine operation conditions, for example: a load of the alternator or status of the air conditioner (on/off, required power of the compressor).

For example, vibration for short moment can be achieved, turning on/off AC. Unfortunately, it’s a peculiarity of the MSD80 algorithms, which has to be taken into account.


Unfortunately, status bits regarding plausibility or “age” of these data are not available, we can only rely on observation of the changes and additional control of the Rough run menu.


The main idea of this entry – if you are evaluating injector data in Stratified charge, idle (for example, after replacing the injector or some other repair works and also – evaluating the performance of the engine in idle), make sure, that data are restored. Not taking in account time, which has passed, INPA ../F5/Shift + F6/F5 menu will show last/stored injector correction values.

These registers are cleaned, deleting fuel adaptations, for example, deleting all second group of adaptations.