![]() ![]() It appears as though the material has become VERY hot and either the metal electrode plates have melted and permeated the stack, or the piezelectric material itself has melted (Google says that lead-zirconium-titanate "PZT" piezo material melts at 1,350 centigrade, approximately).Ī few more observations: here in the UK, VW allegedly gave a two year extended warranty on the injectors and EGR valves after applying the emissions fix. I don't see why mechanical damage would cause discolouration. This begs a few questions at this point: what is the dark material, and what caused it to form? Did it all appear all at once, or did it spread over time? Is it the result of mechanical damage to the stack, or is it the result of electrically inflicted damage?īut, this is what I think might have happened: The damage occurred near to the top of the stack, where the electrical current and voltage should be at their strongest. The dark material has broken through the surface of the ceramic upper insulating layer and some topology is clearly visible too. On failure, my injector at least showed only a few Ohms. Applying a voltage of ~150 Volts causes a minute expansion of the stack, which actuates the injector.Īs the piezoelectric material is a good insulator, one might expect a very high resistance across the injector terminals (or probably a detected open circuit). The positive sheets are connected by a common terminal, as are the negative ones. The actuator element in these injectors comprise of a stack of piezoelectric material sheets, with alternating positive and negative electrode plates between them. VAG's own SSPs 351 and 442 detail how these piezo injectors work and are worth a read. Plus, not all injectors may fail in the same way. There's of course plenty of scope for inflicting further damage, but I thought it was worth a shot. So, I decided to buy a failed one and take it apart in a destructive test. These things can cost £400 EACH to replace! I thought that, if we knew this, it might be possible to reduce its likelihood or prevent it, or just cut down on repair costs. It's not difficult to find complaints of these failing, but I couldn't find any definitive answers on what exactly fails and why. Here in Europe we have 1.6 litre EA189 engines which are fitted with Siemens/VDO/Continental piezo injectors. I'm completely new to forums so have no idea if I'm putting this in the right place or if it will be relevant to many members, this only really applies to European cars but might be of interest anyway. ![]()
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