While ago I began to take an interest regarding cleaning and diagnostics of piezoelectric injectors.Unfortunately then there was no options available – but now situation has changed.
Since March 2017 company DIS technics Ltd, based in Latvia, acquired ASNUS GDI injector stand – now also with 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 beam. Performing this test, some of the “suspicious” nozzles (before cleaning) had a asymmetrical beam, it means – one side was different (typically – with more narrow scattering angle).
c) twitching of the beam. Before there was complaints regarding uneven pace (and ISTA D identified current injector as problematic).
After cleaning all mentioned before defects were gone.
Did the cleaning solved all injector troubles? For sure, not – if 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 is 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 to check offset and proportional grouping data and, if necessary, make the correction.