Dear customers, below we submit to you a complicated case that your colleague Marco, of the MOTOR SYSTEM SNC of BORGOMANERO (NO) he had to face in spite of himself and that only thanks to his professionalism and perseverance was he able to solve. A period of passion...

Reaching 3000 rpm when the engine is warm, the rail and turbine pressure drops. On release of the accelerator and subsequent restart the problem disappears and recurs about every 20 to 50 km.

Gradually over time, exhaust smoke increased.

No error appears in diagnosis.

Checks carried out without solving the problem:
-injection pump
-replacement of injectors
-turbine geometry check
-correct boost circuit pressure

On closer inspection, Marco noticed that a power interface unit (marked Nissan MOTORSPORT) had been fitted and that, due to inexperience, the person who had carried out the modification had altered the flushing on the turbocharger variable to increase airflow, thus circumventing any overboost DTC in the engine control unit.

Result: an overpressure in cases of full throttle that gave an instantaneous reduction only on the airflow, which was solved by partially releasing the load and then resuming, with absolutely no manifestation even for about fifty km afterwards. All completely without any detectable errors.

With this experience, Marco advises us to check for hidden errors, to consult the owner on the car's history in order to quickly focus on the real problem; always with a good dose of patience and persistence, as well as passion and expertise in the automotive field.

We thank Marco for his feedback and important contribution to Techblog. We remain as usual at your disposal .

Good work