More and more, I receive requests for help to solve the problems with the engines of their cars after “disprogramming” of the NOx system. Such “disprogramming” is offered by some chip-tuners and also some enthusiasts.

What does it mean – “disprogramming” the NOx system?

People who have learned how to switch on the NCS software, have noticed the column “NOx system”, and – turn it “off”. “Specialists,” who are familiar with more advanced tools, “clean” the error message map of the MSD to avoid the error messages regarding the NOX system appearing at all.

Is the NCS intended to turn off the NOx system? Of course, no. Data of this configuration are intended to be used during the development and testing of the software.

Is the problem solved by deleting the error messages from the error message map? Of course, no. The error messages don’t appear, but the problem is still present. Even more, such masking of the problem only makes the real solution (and finding the true problem) almost impossible in the future.

How does the engine work after such “upgrades”?

If the NOx system is turned off, using NCS (or any other way), the engine doesn’t use Stratified charge nor Homogeneous lean modes. The engine continues to work only in Homogenous mode. This, as known, is an emergency mode for the N43/N53 series engines. Self-evident – fuel consumption increases.

If not using the Stratified charge, it doesn’t perform many adaptations, and many measurements are not taken. For example, DME cannot measure the leaking of the injectors in idle, their atomization, it doesn’t create LTFT. The engine doesn’t even the performance of the engine in idle, the evening of the cylinder performance in medium load also doesn’t work.

DME uses 5 .. 10 % of full functionality.

Earlier or later, due to not creating adaptations, the error messages regarding fuel trim, Lambda probe trim, misfires, etc., will appear. At this moment, the owner of the car starts to replace the Lambda probes, injectors, and HPFP – all without success.

Even the problems, as if not connected to the engine, appear – the automatic gearbox switches with lashes, the idle of the engine changes, when the load of the engine changes (turning on/off electric consumers, AC, turning the wheel), switching on the AC is with a hit, etc.

All problems are identical to those which appear if the NOx system is damaged.

The situation is even worse in the case of a simple defect in the NOx system. If, in the case of the defect of the NOx system, it’s only necessary to put it in order, and the engine will restore its performance, then in the situation after the “performance” of such “specialists,” the situation is very pitiful. At first, the stock encoding has to be restored, and it can be a complicated task if the error message map has been “cleaned”, the changes are done with unknown software, etc. Of course, restoring the software costs time and money. And, self-evident, after restoring the software, the NOx system also has to be restored. And usually, a lot of money is wasted replacing the hubs, which are actually in perfect order.

In no way can the N43/N53 series engine work without the NOx system. “Disconnection” of the NOx system in any way is the shortest way to huge problems in the near or further future. Bimmerprofs doesn’t suggest using such an “upgrade” solution. The same suggestion corresponds to the disconnection of EGR, control probes, and other modifications.

The NOx system has to be maintained not only for driving to be comfortable and economical. If the fuel mixture is not optimal, the following problems appear:

  • the workload of the CO catalytic converters significantly increases, they get damaged quickly. Unfortunately, these catalytic converters are critically necessary for the car to pass the TI (for the exhaust gasses to fit in the norm);
  • if the car is shivering (misfire problem), the unburned fuel is thrown in the exhaust and explodes there – both CO catalytic converters and Lambda probes are getting damaged.

CO catalytic converters for these cars are expensive (their actual price is 4000 .. 9000 EUR); there are no alternative products. If you want to save yourself from the bill of several thousands of EUR or at least “zoom-out” the problems with CO catalytic converters – repair the NOx system immediately!