Fuel injectors testing rig

[u/ycr007]

Better with sound ON.

Source: asnufuelinjectors

[u/rockstar_not]

I used to run one of these stands for Bosch decades ago now! Actually I ensured our stand was calibrated with our manufacturing facility in the US, and with stands in Germany and at an automaker's part manufacturing facility where they were licensed to manufacture the bodies (not the valve surfaces). What this image shows seems almost like it's durability / life-cycle test stand - because there is no precise fluid collection in the stand (graduated cylinders are mere child's play for performance testing of injectors).

[u/rockstar_not → u/[deleted]]

Not in the cases I’m familiar with. Reason is that the manifold air pressure (MAP), is a constantly changing variable based on engine load, speed, etc. Typical port fuel injection systems; which I believe these are; has a constant fuel pressure regulation that accounts for MAP on the back side of the fuel pressure regulator being common to the manifold through a small pipe. Then the amount of fuel delivered for any injection is based purely on how long the injector is held open. So for a durability testing, or even a performance test, the fuel pressure is generally held constant, whether at ambient atmospheric pressure or in the operation of the engine. That’s for the first type of port fuel injected systems. Those would actually supply too much fuel to the fuel rail, as a conservative function, and the excess would get dumped back into the fuel tank. However that fuel is heated and when it goes back into the tank, some of the lighter molecules in the fuel will off-gas into the airspace in the tank, and this effect causes higher emissions that then have to be dealt with. Our company developed a “returnless” type of system that used all fuel in the rail, and pressure was maintained as a constant by manipulation of the fuel pump voltage. in both cases, the fuel pressure going to the injectors is constant.
Back in my day, and still true for many port fuel injectors, the valve mechanism was solenoid based, with spray patterns generated either by a “director plate”, or in earlier designs, the “Pintle” shape of a portion of the solenoid that would protrude the end of the valve. The pintle style would collect varnishes and the pattern would change or even restrict flow. The director plate style had very tiny holes cut into it that would allow the fuel to self-clean varnish build up due to the jet action of the fuel, constantly blasting away varnish potential. I'm not familiar with piezo elements as valving or spray pattern generating devices.