Once again about adaptations

If the engine performs as intended by the manufacturer, repair specialist don’t have to worry, how the adaptations are created. This is the only way, how to understand the total vacuum of information regarding creation of adaptations for MSD80.

In situations, when the engine experiences any defect, and the defect is repaired quite quickly – everything happens according to the scenario of the manufacturer. Unfortunately the situation, when the car, equipped with N43/N53 engine, has problems with NOx system (in particular, the NOx system is not performing/is damaged) for long time, is quite common. Long time is for years. Several thousands km. There are several reasons for such situation – pure knowledge of repair specialists (say – what so bad can happen, if the NOx sensor is not performing? Higher emissions? Does is has any impact at all?) and also the fast, that the damaged NOx system has no immediate and catastrophic effect on engine (the engine can be started, and you can drive with the car). Yes, the engine tends to vibrate, misfires appear – usually the ignition coils and injectors are “pleaded guilty” (these “repairs” don’t help, but only assists in creation of urban legends, that the N43/N53 engines are not able to perform smoothly).

If the engine  has performed with faulty NOx system for a long time, the creation of adaptations after repair is difficult. Below you will find more detailed description, what can be expected in situation, when the engine was performing in emergency mode (only Homogeneous mixture) and what would be the proper way of action.

Very shortly about problem situation.

The creation and restoring of MSD80 adaptations is quite complicated. Adaptation maps of all three performance modes (Homogeneous, Homogeneous lean and Stratified charge) are connected. If last two modes are prohibited (due to faulty NOx system), the creation of adaptations for all three modes is disturbed. More regarding creation of adaptation read here.

When the NOx system is repaired (new NOx catalytic converter, new NOx sensor, or installing of NOXEM and coding) and the MSD80 receives command to delete (clear) adaptations, actually it don’t delete old adaptations (as, for example, MS43 and similar – older versions of engine control units – did). When the MSD80 receives command “delete adaptations”, actually the largest part of adaptations are still stored in registers. MSD80 sets the status bits, which suggest immediate modification of current adaptations (which have to be updated). The reason of such complicated system is to avoid from significant unevenness of engine or even abnormal performance, if the engine suddenly stays without any adaptation data. MSD80 “thinks”, that replacement or separate components don’t gives such impact of engine’s performance, that all (fuel trim) adaptations has to be rewritten from zero. Only exception – encoding of injectors, after what many adaptations are deleted.

This algorithm works in situations, when the reparation of engine is performed in time, and the replaced component corresponds to specification, intended by manufacturer. Unfortunately, if the engine has been struggling for years or tenths or hundred thousands of kilometers, performing only in emergency (Homogeneous) mode, many specific long term fuel trims (their data) are totally incorrect.

Using such (incorrect) data very often leads to error messages during creating of adaptations,and the creations of adaptations is difficult.

What to do in such situation?

1. Use INPA to delete all adaptations: ../F8/Shift+F9

2. Warm up the engine, perform flywheel adaptations as described here;

3. Switch off the ignition, take out the key and allow MSD80 to “sleep” (wait, till the lighting of start/stop button turns off).

Turn on the engine, connect the INPA, make sure, that after a while MSD80 starts to heat up all Lambda probes.

Open the fuel mixture menu: ../F5/F6

Two line on top are showing heating of probes:

a) line 1 – wideband probe(s) (before CO catalytic converters);

b) line 2 – narrowband/control probes (after CO catalytic converters).

When the warming up of probes is started, the numbers reach 95 .. 99% for 3 .. 6 seconds (so the probes reach work temperature much quicker), then is has to go down to 30 .. 60% and stay in this are. It means, that the probes are maintained in work temperature.

You have to make sure, that Nernst cells of probes reach corresponding values. Open the menu of analogue values: ../F5/F2/F6.

Two bottom lines are showing values of Nernst cells:

a) on the left side: probes before catalytic converters;

b) on the right side: probes after catalytic converters.

Nernst cell values of normally performing probes has to drop to 0/256/512 Ohm during around 20 .. 60 seconds. How to check performance of Lambda probes, read here.


Check the engine work temperature. If the temperature is lower than 90 oC (in the picture: bar on the right side, line 2) – solve the problem with thermal management.


If all parameters, mentioned before, meet the norm, you can start creation of new long term fuel trims. Turn on the fuel mixture menu (../F5/F6 from main menu). All following bars (below Lambda probe heating bar) has to be with 0 values – in such way MSD80 signals, that the request of renewal of adaptations has been accepted.


1. Creating multiplicative initial adaptations of fuel banks.

Very evenly (without fast acceleration) speed up to 60 .. 90 km/h and (preferably, using cruise-control) drive, in the same time observing multiplicative adaptations and integrators for both banks. Taking in account, that the individual adaptations of cylinders have been disturbed for long time, significant difference of multiplicative adaptations for banks can be observed (even +/- 20 .. 30 .. 40% from 0). It’s possible, that such significant difference (and also large dis-balance of cylinders fuel mixture)  can cause MSD80 to decide to register an error message regarding fuel mixture control (bank trim error) or error message regarding adaptation of Lambda probes (trim error of lambda probes or error message regarding probe signal).

Symptoms for such situation:

integrators for one or both banks are suddenly deleted (the values stop changing, stays on 0,0%), also possible, that values of multiplicative adaptations are deleted (they also become 0,000).

What to do: delete recorded error messages (F4/F1/F1 from main menu, then: F5), continue the adaptation, driving smoothly.

The purpose of this stage: values of integrators are re-written (from several tenths of %  they drop down to +/- 5 .. 10% max), values of multiplicative adaptations are stable and unchanging for 3 .. 5 minutes.

If necessary, repeat the procedure of deleting error messages for several times, till the required result has been reached.


2. Creating initial offset (idle) adaptations of fuel banks.

Stop the car with engine running (idle), observe values of offset adaptations and integrators at least for 5 minutes.

If the bank integrator stops to change it’s value (it “freezes” or goes to zero), perform the procedure of deleting error messages again.

The goal: integrators are decreased from large (several tenths %) to compellingly low (+/-5 .. 10% max) values and stays unchanged for several minutes.

If necessary, perform the error message deleting for several times.

Switch off the engine, allow MSD80 to go to sleep, start new session.

In this stage MSD80, if it performs normally (no error message recordings in it’s memory), will start individual adaptations for Homogeneous mixture and Stratified charge.


Individual adaptations for Homogeneous mixture are measured at:

a) idle (measuring mechanical efficiency);

b) short opening of injectors (low rate), measuring deviation of Lambda;

c) long opening of injectors (high rate), measuring deviation of Lambda.

Individual adaptations for Stratified charge are measured at idle run (measuring mechanical efficiency) and partial load (chemical tests).


How to act?

Evenly (without excess torque) speed up and drive evenly with speed 60 .. 90 km/h at least for 10 .. 15 minutes, allow the engine run idle for 10 .. 15 minutes. Repeat the procedure for several times.

All the time follow the adaptations using INPA.


What to check?

1. Learnbits. Target: lines 1, 2 & 4 marked (seen here: ../F5/Shift+F6/F2)

2. Test results for Homogeneous mixture (seen here: ../F5Shift+F6/F3)

First 3 lines are showing measured efficiency for each cylinder.

Next 3 lines: additional correction for cylinders in low temperatures (for now it will be 0, if the creation of adaptations is started for warm engine).

Next 6 lines: applied low/high rate individual corrections.

If you drive evenly, after some time first 3 lines have to start to show data (bar values have to become different from 0). If it doesn’t happens – check the error message memory, delete error messages, continue with creating of adaptations.

3. Individual idle run corrections for Stratified charge (seen here: ./F5/Shift+F6/F5).

When the engine runs in idle in Stratified charge (control: ../F9/F1), first 6 lines has to start to show results of test (bar values have to become different from 0). Next 6 lines: data for chemical tests (partial load)

Attention: if the applied value of correction for any of cylinders will exceed allowed region (green), MSD80 will record an error message regarding cylinder efficiency.

In this situation – delete the error message and continue to create adaptations. Make attention to the corresponding injector (replace, if the problem remains after several driving sessions).

Such situation can appear, if old adaptations (before defect of NOx system) are significantly different from existing situation. MSD80 will repeat measurements of cylinder efficiency for several times, with each time reducing difference from ideal situation – the engine will start to run more evenly!

Note: if the engine had long time performed with defect of NOx system, the difference of measured efficiency for one (or even more cylinders) can be significant, and it does not indicates a defect of injector or any other component!

4. Instantaneous corrections (seen here: ../F5/Shift+F6/F1)

Actual data are visible in first 6 lines (time of opening and applied multiplicative correction).

Attention: if correction, applied to any of injectors exceeds allowed area (green area in line 4 to 6), MSD80 will record error message regarding cylinder (or even corresponding bank) fuel trim.

In this situation – delete the error message and continue to create adaptations.

Note: if the engine had long time performed with defect of NOx system, the difference of measured efficiency for one (or even more cylinders) can be significant, and it does not indicates a defect of injector or any other component!

5. Corrections of cylinder efficiency in idle (when the engine runs in Homogeneous mode and Stratified charge mode, seen here: ../F5/F7).

Note: in this menu cylinders in firing order!

The values of all cylinders have to switch polarity quite regularly. If it doesn’t happens longer than 5 .. 10 seconds (any of cylinders shows increased or decreased efficiency, the vibration can be felt) – check the error message memory (if necessary – delete the error messages) and continue the adaptations (both waiting for 5 minutes and repeating driving sessions and idle).

If adaptation for warm engine are successfully finished, allow the engine to cool down.

Turn on the cold engine, allow it to warm up in idle. If necessary, delete the error messages, which appear during warming up. During this time MSD80 will perform additional bank corrections for cold engine and also will create individual corrections for lower temperatures of engine.

In such situation, the creation of adaptations will require a lot of patience and a lot of time. Such is price, which has to be paid, if the engine has not been kept in technical order for a long time.

If the car has been purchased by real BMW enthusiast, you can perform repeated adaptations. On second time, everything has to happen much more easier and quicker, and without error messages. Repeated process will give best possible result.



Related entries:


Management of Lambda probes

N43/N53 operation modes. Basics