While ago I began to take interest regarding cleaning and diagnostics of piezoelectric injectors. Unfortunately, then there were no options available – but now the situation has changed.
Since March 2017 company DIS technics Ltd, based in Latvia, acquired ASNU GDI injector stand – now also with an operational module for piezoelectric injectors. I was honored to be a “test pilot” for it. I tested not only injectors of my car, but also items, which were supplied from local BMW alternative service centers: Bavaria auto Ltd and Latbema Ltd as test samples.
The good news: this current ASNU stand gives a quite clear view of such defects of piezoelectric injectors:
a) leaking in closed position – simple, but one of the basic tests (note relating test pressure – below);
b) symmetry and scattering of the beam. Performing this test, some of the “suspicious” nozzles (before cleaning) had an asymmetrical beam, it means – one side was different (typically – with a more narrow scattering angle).
c) twitching of the beam. Before there were complaints regarding uneven pace (and ISTA D identified current injector as problematic).
After cleaning all mentioned before defects were gone.
Did the cleaning solve all injector troubles? For sure, not – if the piezo element has defects (for example micro-cracks), or mechanical wear – it won’t help. But, when I saw the residues left on the nozzle only after 500 km run – I made my conclusions, that the quality of fuel is far from perfect, and cleaning of injectors – especially piezoelectric ones – is a must.
Testing and cleaning are performed in the following way:
a) visual inspection of performance;
b) cleaning for 20 .. 30 minutes – in ultrasound bath;
b) again visual inspection, if necessary – cleaning process is repeated;
c) evaluation of flow rate (for now only with limited precision, because the flow rate grouping principle has not been figured out).
For safety reasons, the pressure has been reduced to 5 bar. Unfortunately, such pressure is insufficient to find all leakages.
Cleaning of nozzles with ultrasound. This type of cleaning has limited efficiency because the cleaning agent is not pumped through the injector.
Evaluation of flow rate.
Visual inspection of beam.