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Bench Testing Code (outputs, math and injectors) 
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LQFP144 - On Top Of The Game
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EssEss wrote:
AbeFM wrote:
I have seen people monitor the current to the injector (which I kinda like - you can actually SEE the pintle stop moving).


Dynamic flow is no way related to this trick (or the knock sensor zip-tie trick). I spent some time on my own injector flowbench to prove it to a co-worker. Check this link for a little more insight: http://www.injectordynamics.com/dynamic-characterization.html

this guy does it right, and I've independently verified it - most people don't go to this extent, except ford and myself :D. Every single injector I've characterized exhibits the same behavior around opening which a static straight-line interpolation misses. If you use big injectors and low duty the error turns out to be pretty big - especially if you didn't characterize it wrt battv.

I totally agree.

And I wanted to add that the dead time is not only related to the opening but also closing time and that neither are step functions where you have no flow followed by full flow at the exact time the pintle has moved (or the reverse for closing). One more thing to take into consideration is that the driver used for the test also has an impact on the measurements so the best is to use the same driver circuits as those in the ECU or the actually use the ECU for the test.

Jean


Mon Jan 17, 2011 6:59 pm
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jbelanger wrote:
And I wanted to add that the dead time is not only related to the opening but also closing time and that neither are step functions where you have no flow followed by full flow at the exact time the pintle has moved (or the reverse for closing).

Of course, but can you explain how that matters if you can simplify it to a period of non flow and period of flow for a given voltage (at the injector) combination?

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One more thing to take into consideration is that the driver used for the test also has an impact on the measurements so the best is to use the same driver circuits as those in the ECU or the actually use the ECU for the test.

That's a great point, however unless the driver and wiring is reactive, the voltage at the injector (once stabilised) will give you consistent results, I would think.

Also, why does Abe's method not work, if it doesn't. I've read EssEss' link before and either missed the point or it seems simple to me.

Fred.

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Mon Jan 17, 2011 11:37 pm
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I stopped and had a read of this this morning while working on the Bench Test stuff and upon reading a little more slowly, now that I'm just living in one place, and have food, and no time limitations, etc, it's obvious why the simple way is not good enough, especially not with my goal of being a system tailored to high power from low displacement setups. I'll work on integrating the information from that site into the code in future, but for now, a V vs DT curve is sufficient to get everyone running and running pretty well.

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Fri Jun 03, 2011 9:54 am
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I'm ignorant about how this works. I'm sure it's a special firmware that has the software wheel decoder hard coded into it, but as for things like setting a specific pulse width, how do you do that? Does that require changing a config file or something then compiling? I believe this code/firmware comes with the git hub vanilla, but I don't recall much for notes about how to use it. I haven't checked out a copy for a couple weeks, perhaps I should grab the latest. Is there a README or something in the vanilla checkout that would answer the basic questions like how to use the bench test code? For example do I modify a config file and compile a specific firmware for the test, or do I send commands over the USB/COM port for a live interaction?


Thu Jun 09, 2011 1:58 am
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I apologise! I linked this thread from the new one, but not vice versa! Here is the documentation:

viewtopic.php?f=56&t=1180

The new thread has the details of how it works, and will be the dev thread for the future of it, as it evolves. Keep the ideas etc in here, and the other one as clean as possible, please.

If you want help configuring it to test something, and it's not obvious, let me know and we will A get you configured B update the docs to make it more obvious.

Fred.

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Thu Jun 09, 2011 9:52 am
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