What to do, when the good idea fails?

Try to fix it, solve it? Yes of course. How does Siemens (the BMW AG partner) succeed in solving the Rough run problem for MSD80? Very poor.

Problem – false Rough run error messages, caused by uneven road or change of driving conditions (load, accelerator position etc.) The error message 3104: Uneven run/Stratified charge – known for everyone.

Let’s see, how the problem is solved for version 7595182 of engine N43B20:

Such picture is seen, when the cylinder No.1 has been switched off manually. As we see, in case of 0% efficiency of cylinder No.1 (it’s switched off) INPA shows an average difference from ideal by only 0,2 units. It means, that comparing to the typical software release, the sensitivity of system has been decreased 15 .. 30 times! Additionally, the short time unevenness of cylinders is being quenched even more significantly – when the engine performs in normal mode, cylinder bars differences from ideal are only till +/- 0,005 units, it means, the immediate sensitivity is decreased for around 100 times!

Of course, with such parameters, the error message 3014 will not appear in error message memory never! Even more – no error messages regarding cylinder misfire will appear, even if any of cylinders will not function.

Is this a solution to a problem? Yes and no. Such “solution” eliminates all problems, associated with error message 3014 (engine switching to Homogeneous lean or even in Homogeneous mode, a re-creation of adaptations etc.), but also at the same time eliminates very important part of self-diagnostics – control of normal cylinder performance.

How to perform this test, read here.


Related entries:

MSD80 software releases

Specific features of MSD80