Error messages. Part 2

 

Very brief insight into history.

When first electronic management units for the engine management were introduced (for example, Jetronic), they were analog, without any possibility of self-diagnostics.

First Motronic (and similar) systems had first, very primitive control possibilities of connections and actuators.

Next generation of control units already had adaptations, adaptation maps were used. Error messages had status marks (passive/active), counters of sporadic error messages were registered. If the defect of connection or actuator was detected, it was not enough only top replace the damaged knot. Usage of actuator or sensor was restored only after deleting corresponding error message. Unfortunately, many repair engineers are not familiar with this nuance, and even repairs of fifteen-twenty-year-old cars very often are “unsuccessful”- the problem doesn’t disappear after only replacing the damaged knot.

 

At this moment very logical question appears:

is it enough for MSV/MSD engine management units to only delete error message after replacing damaged knot?

The short answer is: NO, it’s not enough!

 

MSV/MSD engine management units create multidimensional adaptation maps. The number of such maps can reach over one hundred units, they are related to each other and very complicated.

If MSV/MSD detects any significant problem with the sensor or actuator, it stops creating current part of adaptations, another part – don’t even uses old, created before, adaptations.

Usually, the creation of fuel adaptations, which define basic functionality, is stopped, it means, offset type bank adaptations, multiplicative adaptations, additional adaptations accord the temperature, etc.

The use of “upper level” adaptations is completely stopped, it means – no mechanical efficiency of cylinders and chemical efficiency tests are performed, the cylinder performance is not evened not in idle, not in low/average/high load conditions.

What happens, if the repair of the engine (with MSV/MSD engine management system) is “completed” with replacing damaged knot and deleting related error messages?

The engine continues to shiver, misfires are observed, with time – inexplicable problems with fuel maintenance, error messages regarding fuel trim, Lambda probes, CO catalytic converters, etc.

Why such situations appear?

MSV/MSD restores full functionality only after deleting current adaptations. Together with adaptations, status bits of error messages are also deleted (otherwise they are not available for user/service specialist).

 

Adaptations have to be deleted for:

a) damaged knot;

b) all knots, which performance depends on the damaged knot.

Typically – depending adaptations are all fuel mixture adaptations.

 

Accordingly, for example, in case of throttle damage, after replacement:

a) all error messages have to be with passive status, it means, MSV/MSD confirms, that the problem is solved; no new error messages after deleting old ones appear;

b) adaptations of throttle has to be deleted;

c) all group of fuel mixture adaptations has to be deleted ../F8/F2/Shift +F9*

After performing this procedure, new initial adaptations has to be created, as described here.

* if N43/N53series engine is equipped with OEM NOx sensor, BEFORE deleting these adaptations, forced desulphation session has to be performed, as described here.

 

Of course, if all repairs are done, accurately following requirements of ISTA D, all necessary adaptations are deleted as provided by Siemens (developer of engine management system). Unfortunately, it is enough only once mistakenly refuse of ISTA D offer to delete the adaptations, or simply only delete error messages, not following the repair plan, and… Problems in near or far future are guaranteed.

Because of this reason, BMW AG in their SI very often indicates – if there are no direct signs or one or another defect, as a solution of the problem use… deleting of adaptations! And very often after this procedure a miracle happens – many inexplicable problems disappear!

 

Here, an example from SI, what to do (how to perform diagnostics) in case of problems with fuel supply system – as the last stage mentioned: re-adapting of the engine. It means – deleting old adaptations, creating new (basic) adaptations. Even this stage is marked by bold letters, BMG AG has given no explanation, why this stage is so important. Accordingly – even many repair specialists in dealer’s service centers are ignoring this stage as unnecessary (say, the customer will drive a bit more – adaptations will restore).

 

ISTA D don’t give ANY information regarding exactly what earlier problems the creation of adaptations is stopped.

INPA allows indirectly detect, that the “upper level” adaptations are not applied. If we check ../F5/Shift +F6/F1, it means, total data regarding actual parameters of cylinders, we can detect:

a) opening times of injectors in idle are almost similar, proportional to input coding data (it means, no additional corrections are applied);

b) multiplicative corrections of injectors are very “close” one to other and are proportional to input coding – additional corrections, measured in cylinder chemical (or mechanical) efficiency tests, are not applied.

In the image: example – MSD80 has turned off the creation of “upper” level of cylinder-individual adaptations. Of course, as indirect confirmation of this problem: ../F5/F7: disbalance between mechanical efficiency measurements of cylinders (at idle), which MSV/MSD is not even trying to correct.

If any of signs, mentioned before, is detected – obviously, the engine management system performs in limited functionality mode, depending on the history of defects – corresponding + total adaptations has to be deleted, new initial (flywheel + banks) fuel mixture adaptations have to be created. Only after performing these operations, during next several hundreds of kilometers the engine management system will restore/create necessary adaptations.

At the same time have to conclude, that the management units of such complexity could be successfully repaired only with highest level diagnostic tools from manufacturer/dealer: INPA and ISTA D.

 

What adaptations should be deleted (depending on damaged knot):

*including after replacing and coding of the injector

**obligatory: encoding of the replaced component via ISTA D

***it’s highly important to perform correct flywheel adaptations

A = adaptations of exact knot

B = all fuel adaptations, 2nd group: ../F8/F2/Shift+F9

 

Related entries:

Error messages. Intro

Diagnostics with INPA. Part 1