While ago I began to take an 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;
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 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 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, but clearness about injectors imperfection is quite good.
Cleaning of nozzles with ultrasound.
Evaluation of flow rate.
Visual inspection of beam.
Costs: small part of price of a new injector – for sure, I will clean my car’s piezoelectric injectors every 50’000 km.
P.S.: It would be excellent if in the near future the producers would decipher injectors grouping conditions. It would allow checking offset and proportional grouping data and, if necessary, make the correction.