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Appreciate all the effort you put into this project.
I would also like to build one.
I will PM you with my email for the software and the screen definition file
thank you for taking the time to draw this appreciated
Sent
Originally Posted by RGSS
Appreciate all the effort you put into this project.
I would also like to build one.
I will PM you with my email for the software and the screen definition file
Sent
Just a couple of comments. You will be blown away by how sensitive the 1KG sensors are compared to visually checking a graduated cylinder.
It was pointed out to me that my display is a 3.2", not 2.3" Thanks, It's been a while since I played with this.
One of the screens is a calibration screen. I calibrate all 4 sensors with 500ML of fluid.
Note that the 1.1V internal reference voltage in the Mega is turned on and used. So if you use any other analog ports, make sure you keep the voltage below 1.1V and adjust you calculations accordingly. It's used to get a more accurate reading across the .1 ohm resistor.
There is alot of information stored in the EEPROM of the mega. The first time the program is run, this info EEPROM data will not be there. There is a line of code( //init_all_eeprom(); ) that needs to be uncommented the first time to initialize all the EEPROM data. Search for this line, uncomment it, and run it once. Then you can comment it back up. This will initialize all the EEPROM data. From that point on, whenever the program starts, it will read all the data stored in the EEPROM.
I have lots of those .1 ohm resistors (leftovers from one of my businesses), if you want one, just send me any prepaid, addressed return envelope and I'll send you one.
The home screen is used to fill and empty the fuel rail, run a current profile on an injector, turn the fuel pump on and off, and lead you to all the other screens.
The fill button is used to run the pump and injectors for a few seconds to remove any air from the fuel lines and injectors.
The empty button is used in conjunction with the air pump and valve that replaces the fluid in the lines and in the injectors with air so they there is no fluid all over my hand when I remove the injectors from the fuel rail. This button just runs the injectors until there is no more fluid coming out of them. Once they are empty, push the empty button again to stop the function. The air pump and diverter valve are manually operated. I can describe how that is set up in case anyone wants to go there. If you don't have the air pump setup, at least it will remove any pressure in the fuel lines.
The Start Amps test button runs the injectors for a split second. In that time, it does a couple of hundred samples of the current through each the injectors and spits out the results to the Serial port. If you have the laptop attached, then you can copy that data and do as you wish. It's in CSV form so go at it. It's amazing how fast this test is for all 4 injectors.
The pump button just turns the pump on and off
One of the first buttons you might try is the calibrate button. This will let you calibrate the sensors the first time through and save the results so you don't need to do this each time.
I forgot what the progress bar does on this screen. I
I don't think I have the fuel pressure, volts and temperature sensors wired in, but there are stubs in the program to make these show in the display if you go and add these.
The white buttons lead you to the other screens.
The scale screen is just to test and demonstrate the accuracy and sensitivity of the scales. I put weight on one of the scales, and then add a pinch of sand and show friends how sensitive they are.
The Single test screen lets you test a single injector or all 4 injectors with a single pulsewidth and number of pulses. A number of preprogrammed single tests are saved for common tests and can be edited with the Single Edit acreen
The Bulk test screen runs all of the single tests that are stored for one or 4 injectors. The bulk edit lets you customize those.
The Multi bulk lets you pick one of the preprogrammed bulk tests. These can only be edited in the code. Just pick which bulk test you want, start it, walk away and when it's done, the results are spit out to the serial port.
The Engine screen simulates an engine running by sequentially running the injectors just like in a real vehicle at a chosen RPM and pulsewidth. Injectors are never batch run in any of the tests on the bench.
Lets you define a "tare" for each sensor so that are all calibrated and saved into memory.
I use 500ml for my calibration because I have a 500ML graduated cylinder. A bigger cylinder will get you a more accurate reading and a better calibration reading on the scales. The curr value is the num of ML of the calibration sample. You can change that using the increment and decrement buttons where the new size will show up in the new value. Once your new value is correct, just push the commit button and it will be saved in memory. The commit is only for the calibration sample size.
To calibrate each scale, I have and empty 1 liter bottle. Put the empty bottle on one of the scales, #1 for example. Then press the #1 Empty button. That will determine the empty weight. Then I use another identical bottle, filled with exactly 500ml of fluid and put it on #1. Then hit the #1 Full button. Only after reading both the empty and full values for #1, the calibration for #1 will automatically be saved. Do this for the rest of the scales.
BTW, for calibration purposes, the scales are read many times, I don't remember exactly, maybe 20 or 50 times and the average is used.
It simply measures the fluid on any of the scales and reports it back. Good for periodically checking the calibration of the scales and for demos and testing each of the scales.
I have bottle filled with dry sand that weights exactly the same as a bottle filled with 500ML of fluid. I use this to test and calibrate so I don't have to mess with fluids each time.
A fun demo I do is to weigh the 500ML bottle of sand. Then take a pinch of sand and add it to the top of the sealed bottle, weigh it again and show how sensitive the scale is. Then remove the sand and weigh it again.
This runs the injectors exactly as if they were in an engine rather than separately for a predetermined RPM, Duty cycle Percentage and number of seconds.
A number of these tests can be pre stored and given a test# so I don't have to enter the parameters each time, but just toggle through the pre stored tests using the Test + or Test - buttons. So for example, you might want save a run that is a 10 second test at 5000 RPM with a 90% duty cycle. I don't remember how may pre stored runs it can save, maybe 7 to 10.
Once a pre stored test is selected, it can be run with the Run button. Run all button will run all the pre stored tests.
If I don't like a particualar pre stored test, you can change it using the increment and decrement and commit buttons.
The progress bar let's you know how much of the test is done so far.
The screen is not actually that useful for getting the characteristics of the injectors, but gives you an idea of how much fuel is used in real world like test like a 9 seconds drag run at a certain duty cycle.
Lets me manually check 1 or all 4 injectors at any pulsewidth (in microseconds), Period (in microseconds) and number of pulses.
For example, at 1000 RPM for a 4 stroke an injector is fired 500 times(1000 / 2 = 500) in a minute (500 / 60 = 8.3333) or 8.3333 times per second. In milliseconds that is (1 / 8.3333 = 120) or once every 120 milliseconds ( 120 * 1000 = 120000) or every 120,000 microseconds At 8000 RPM the period is 15000 microseconds. That's the entire time between injection cycles, but we don't keep the injector on 100% of the time, so for 1000 RPM a 10% duty cycle would have the injector on for 10% of the period and off for 90% of the period or (120000 / 10 = 12000 or a injector pulsewidth of 12000 microseconds. It's in microseconds, because this test rig is way may accurate than milliseconds. The difference between a 1 to 2 millisecond pulsewidth can be stalling at idle or too rich at idle depending on the injector. So for example, a 15,000 microsecond period with a 13,500 pulsewidth is 8000 RPM at 90% duty cycle.
I like to start my tests at under a millisecond and see where the injector begins to flow. This is the delay time.
Single test edit screen
Lets me customize any one of the 10 stored single test.
This is where I do most of the testing. A collection of bulk tests are run with the touch of one button. Walk away and when the collection of bulk tests are done, the results are spit out to the laptop in CSV form.
Lets me calibrate the difference in weight between mineral spirits used in the test bench and real gasoline (if I remember correctly). Mineral spirits is the closest in weight and viscosity to gasoline, but safer to some extent.
Lets me decide how may times the scale will weigh a sample of fluid (and average it out) for each reading.
Lets me decide how may times the scale will weigh the scale (and average it out) for calibration screen and scale screens only.
And also the ability to turn certain debugging features on and off without having to change the software.
LSswap thats some great work. If your sharing your code id like to get a copy. Thanks
If anyone wants a copy of all the Mega code and screen definition files for the nextion, Just PM me, letting me know you want the files for the Calibration and Injector test bench and provide your email address. I'm going to add the code, Nextion definitions, and also the cad files for the bottle holders and spacers into a zip file and email that going forward. Less work for me than finding all the files each time. If it gets out of hand, I may have to create a github, but I've been avoiding that so far.
LSswap, you have singlehandedly convinced me to join a forum which is rare for me. This is very impressive work! I have done some simple Arduino stuff like a PWM cooling fan controller but this is next-level stuff. Especially sending the data over serial in a CSV! I will send you a PM. :-)
Speaking of injector flow rates, does anyone know if the GM ECUs have per-injector flowrate compensation? I am using that feature in my Subaru (2006 STI).
Good afternoon I ran across this thread while looking for options on a test/ flow bench for my fuel injector. Could I be put on the list for construction data, parts list and software. I would like to build a test set like this one, really great work by the way thanks
10-31-2023, 10:30 PM
