Ok, so I'm starting to put together a parts list. Below is the power supply that they are using in the 55v eTec box. If I want to go adjustable from 55 to 12v, I will need to get an adjustable box, but maybe for now I should work on making a dedicated 55V box.

2 - 556 or 555 timers - how do I go about choosing which one I need there are lots to choose from. - This is the piece that will set the signal duty cycle, correct?

1- CD4017 Counter - I assume this is what is going to send the signal to each injector individually?

https://www.digikey.ca/product-detail/en/cui-inc/PDRA-240-48/102-4965-ND/9555718

If doing this myself, I would buy a pulse generator from EBay and some logic level mosfets, equal number of N and P. With the pulse generator you could vary the pulse length and frequency. The mosfets would give both positive and negative pluses. Can see no reason why you would need the CD4017, each pair of mosfets would have a lead with a connector to match the injector. so if you were cleaning 4 just connect 4, if 6 connect 6.

https://en.wikipedia.org/wiki/Pulse_generator

 

Can see no reason why you would need the CD4017

The intention was to reduce the instantaneous current draw, by sequencing the injector pulsing rather than pulsing them all simultaneously.

 

Can you monitor the injector current during the cleaning process? (You might need to insert a current-sense resistor in series with the injector to do that).
Since you can monitor the existing cleaning pulse voltage, why not use that voltage, instead of separate timers, to trigger/control the sequential pulse timing for multiple injectors?

I should be able to monitor that. Ill see if I can get something like that cone tonight, I'm behind on my customer jobs right now so it might be tight.

If I am following you correctly, your saying we should be using the pulse of the original test equipment, to trigger the pulses of this box, correct?

 

If I am following you correctly, your saying we should be using the pulse of the original test equipment, to trigger the pulses of this box, correct?

That's not necessary, since you'd rather have a stand-alone. As mentioned, you can buy a pre-assembled pulse generator on ebay very inexpensively.

 

Ok so then the current recommendation is to buy a pre-made pulse generator and use that?

I found some interesting documents online the first is about this injector drive controller the LM1949. It looks like something like this could easily be adapted for this purpose.
http://www.ti.com/lit/ds/symlink/lm1949.pdf

It seems this document might also have some relevant information.
http://www.globalcis.org/ijiip/ppl/IJIIP-073059JE.pdf

 

If I am following you correctly, your saying we should be using the pulse of the original test equipment, to trigger the pulses of this box, correct?

I'm not saying "should" (and I was referring to the cleaning kit rather than the testing equipment, if there's a difference), but if that pulse profile is known to drive the injector properly without any issues then it would avoid/reduce the possibility of wrong /harmful pulse widths being used in a DIY or non-OEM off-the-shelf pulse generator. Your call.
Your scope shot shows pulse widths, but what is the pulse repetition rate?

 

I can definitely find out the repetition of the pulses when being cleaned. My preference would still be a complete stand-alone. As my other equipment is an "all in one" tester and cleaner. So if I'm using that to pulse this system, then it is still tied up. Its not a huge deal to do that at this point but I'm definitely trying to plan for the future, when it could be a problem.

My biggest hesitation on using an adjustable pulse generator is employees. I don't think I would have a problem using it personally, but I don't trust that someone wouldn't mess with the settings and fry out a set of injectors. The eTec injectors run ~600+ a piece, so that would get extremely expensive for me. It would be nice to have something we could just turn on and go.

EDIT: I'm also coming to the realization that I don't know enough about circuit design and components to assemble this board, or even design it once we figure out the proper components, so if any of you do this for a living or side-job, I would definitely like to have someone price this out.

 

I don't trust that someone wouldn't mess with the settings.

Don't have any external settings. Put anti-vandal seals on the box.

 

I saw it in the link Alec gave in post #3.
View attachment 204465



If you look at how they are made and work(in the illustration above) both pulses are needed to clean the whole injector, it works as a pump too.

As I look at that drawing there is nothing that the reverse pulsw does except sprrd the return of the coil. That is important for running but how is it important for cleaning, when the rest of the cleaning is done by an ultrasonic cleaner?

 

I'm not sure why we are still on the question of why the reverse pulse needs to be there.

I own and use a commercial cleaner for these injectors. It reverses the pulse when it cleans. All I want to do is replicate that pulse.

So my question is now, is there someone that is able to design this circuit for me and build me this board?

 

As I look at that drawing there is nothing that the reverse pulsw does except sprrd the return of the coil.

Go and read the link. Did you see where the injector has an inlet and an out let for fuel? The main reason injectors need cleaning is the gum/varnish from the alcohol in today's fuels. When left to sit over a winter, like mowers and boats it clogs up the jets and passages.

Must have missed where he said this was done by a ultrasonic cleaner. Can you show me which post that was? Most injectors are cleaned by high pressure chemical cleaning agents being pumped through them while they are being pulsed.

 

All I want to do is replicate that pulse.

But we still don't know what the actual pulse voltage, current, and repetition rate are. Those figures are key for replication. Your scope shot can't be relied on if ±24kV is admittedly dodgy.

 

But we still don't know what the actual pulse voltage, current, and repetition rate are. Those figures are key for replication. Your scope shot can't be relied on if ±24kV is admittedly dodgy.

Certainly if the frequency is known we can calculate the times, and the amplitudes can be adjustable by setting a power supply. And instead of a negative pulse, a positive bias on the other injector lead can duplicate whatever benefit is found from that. And still, distributing the pulses by means of an IC counter will be the way to go. For the negative part, two timers triggered by the fall of the drive pulse. the first for that short delay and the second for the pulse width. Now all that is needed is to know the current so that the driver transister type can be selected. Several folks common to this thread have the drawing software and some of them can work from my descriptions and create the circuit.

 

Ok, perfect! Let me get a better look at the pulses and see if I can get some solid readings on voltage, current, and repetition rate. For the repetition rate, can I throw my multimeter on the Hz setting? Or maybe that won't work. Either way I'm hooking up the scope. I can also check the voltage coming out of the machine with my multimeter.

 

can I throw my multimeter on the Hz setting? Or maybe that won't work.

May not work if the meter is expecting a sine-wave. Meters can give misleading results with pulse inputs of odd shapes. The scope should tell all, once you've sorted out why it is lying to you.

 

May not work if the meter is expecting a sine-wave. Meters can give misleading results with pulse inputs of odd shapes. The scope should tell all, once you've sorted out why it is lying to you.

Probably the meter reading will be either OK or obviously off. The pulses should certainly be audible if an injector is running. And there is always the evaluation criteria: "Is this number REASONABLE?" I learned that in my first year engineering classes.

 

I can see how the negative pulse may be necessary to help it draw more fuel, thinking that they may have kept the return spring light intentionally so the forward pulse doesn't have to work against it to build pressure

I've been re-thinking the reverse pulse issue and concede that it may serve a useful purpose in the cleaning application.
1) If the injector is thoroughly gummed up, then a light-action return spring may well need assistance to return the coil and pintle.
2) The reverse pulse might avoid any vulnerable part of the injector becoming permanently magnetised, which could adversely affect the injector operation in normal use.

Edit:
The guy in this video (spoiled by bad language IMO) explains the eTec injector operation in normal use, but doesn't mention any reverse pulse. He does, however, seem to have access to printed technical data which, at about 19:00 into the video, he makes use of.

 

I've been re-thinking the reverse pulse issue and concede that it may serve a useful purpose in the cleaning application.
1) If the injector is thoroughly gummed up, then a light-action return spring may well need assistance to return the coil.
2) The reverse pulse might avoid any vulnerable part of the injector becoming permanently magnetised, which could adversely affect the injector operation in normal use.

Edit:
The guy in this video explains the eTec injector operation in normal use, but doesn't mention any reverse pulse. He does, however, seem to have access to printed technical data which, at about 19:00 into the video, he makes use of.

In one industrial assembly machine that I am a bit familiar with a reverse polarity pulse was used to counter-act the residual magnetism that would build up and prevent the part release. The machine used an electromagnet to pick up a small part, and after a while the parts would not release properly. So the reverse pulse was able to cancel the built up magnetism.

 

I understand a reverse pulse is also used on big scrapyard electro-magnets for the same reason.

 

The reverse pulse might avoid any vulnerable part of the injector becoming permanently magnetised, which could adversely affect the injector operation in normal use.

In one industrial assembly machine that I am a bit familiar with a reverse polarity pulse was used to counter-act the residual magnetism that would build up and prevent the part release.

Did you guys watch the video or look at the Alec's first link? Alec you should have since you posted both.

First off what is getting magnetized? The body of the injector is nonmagnetic, all of the parts other than maybe the springs(and they are most likely stainless steel) are nonmagnetic. It is not a standard solenoid type injector! It is a voice coil that is used to make an injector. An injector that is also a fuel pump!

You only need to watch the first 7 or so minutes of that video to see that you guys are on the wrong path in this problem. Look at the size of the injector that he shows on a cylinder head, no standard fuel rail injector is anywhere as big as it. It's huge!

The reverse pulse is one of the things that makes this thing work. It is like a hydraulic cylinder that opens a normal pintle type injector, just as it shows in Alecs first link When he shows a hammer hitting a hypodermic syringe to push fluid through a hose nozzle.