I'm also building an injector flow bench as well and just found this thread.
dgallup said:
"Lots of places can do injector flow testing, very few can do accurate, repeatable flow testing. Stay away from anybody with an ASNU tester, they are a total piece of junk."
Could someone elaborate on why? I haven't ever seen one, I'd like to understand what the deficiencies are to avoid making the same mistakes. Maybe I'm thinking too simplistic here, but I was envisioning on the mechanical side simply making a stand with a tank for the fluid and a pump, then running into a rail with an adjustable fuel pressure regulator (with a gauge). Have the injectors spray into graduated cylinders or something like we used in a chemistry lab to measure the output.
On the electronics side, I'd run the injectors for a set length of time. Fire all the injectors simultaneously, have a user adjustable pulse width, have the user set the "engine RPM" to simulate the firing frequency of a running engine.
What am I missing here? Wouldn't the ASNU device (or any injector tester) work similarly? Why would this not be accurate? This really doesn't seem very complex, which is why I'm perplexed by the cost of these testers and willing to build my own!
To clean the injectors, it appears that ASNU is simply using an ultrasonic jewelry cleaning machine that you can buy for $40.00 or so, filling it with some fluid and soaking the injectors in there. Any idea on what cleaning fluid to use? I was just thinking of filling the bowl with some carb/injector cleaning fluid you'd get from an auto parts store. Or running the pressurized cleaners (such as 3M) through the rail as I cycled the injectors?
Any advice/thoughts would be appreciated. Thanks.