So I'm bored again at work today so I decided to hook up the 034EFI to the scope to make sure that it was actually producing the pulse width that it said that it was.

I couldn't convince it to accept a square wave from the arbitrary waveform generator as a tach signal, so I switched it over to continuous mode. It produced the correct pulse across both injector drivers, the width was almost exactly what the Super Fueler program said that it was. Cool.

Then I went about to simulate 2 "turbo" 450 cc/min injector wired in parallel, which would be about 1.25 ohms. I found a beefy resistor and hooked the thing up. The power supply read "current limiting" so I thought to myself "WTF?"

I was retarded. I should have done the math before I hooked the thing up. I was lucky I had the current limiter on my power supply set to a reasonable value so I didn't burn up the controller.

Assuming that there are no resistors already in series with the injector drivers, neglecting the resistance of the wires, and defining a conservative value of 100% duty cycle:
1.25 ohms, at 12 volts, draws 9.6 amps through the injector drivers. 9.6 amps * 12 volts = 115.2 watts! Holy shit! The injector drivers definitely can't handle that.

I found out the hard way that just like with the stock ECU, the 034EFI does not want to see a low input impedance.

I poked around some old threads and found out that the best place to put a resistor is on the constant +12 side of the injector drivers, not the pulsed ground side. I found a good resistor available at Shit Shack. It's an 8 ohm, 20 watt resistor, so let's do some more math.

8 ohms + 1.25 ohms = 9.25 ohms. 9.25 ohms at 12 volts draws about 1.3 amps. 1.3 amps at 12 volts is 15.6 watts, which is well below the advertised limit.

Corbin's 8-injector setup:


My proposed one:


Anyone care to double check this?

While this all sounds very interesting and technical, I'm just going to follow along in the hopes I learn something. I guess, in layman's terms this would be good why? To make the 034 more accurate in dealing with the drivers? To proling the life of the injectors? Their drivers? Teehee. I are a no0b, but I am starting to do some research on this set up and I appreciate the people like yourself who are sharing what they're finding out to make it easier for others. :thumbsup

Brian,

People who try to use the stock DSM 450 cc/min injectors suffer from the same problem as people who try to use these injectors with the stock ECU. The resistor pack workaround is explained here:

http://forums.2gnt.com/dcboard.php?az=show_topic&forum=26&topic_id=148&mesg_id=148&page=

I just found this out today, which was a lot better than finding it out after I started the car up for the first time since adding the new system.

After searching through some old threads, this was already discovered by someone else, here's the thread:

http://forums.2gnt.com/dcboard.php?az=show_topic&forum=8&topic_id=68273&mesg_id=68273&listing_type=search#68567

Anyone starting an 8 injector project should certainly pay attention to what they install. They will have to understand the implications involved with every part substitution. What about running two DSM 450's in series on each driver? That should still give acceptable power consumption.

Corbin

'95 ESI-T
HRC+FMIC+ETC...



Gimme fuel...Gimme fire...Gimme that which I desire

I guess series could work too, one would not need as large as a resistor in that application, but I'd rather have the voltage drop the same across each injector, personal preference I guess.

why is there so much talk about using DSM 450's for anything for us? why do a lot of guys want them? arent you supposed to have to do some resistorizing to get then to work? are they that much cheaper that it justifies the headache? what gives? just curious.

Some 4G63 owners will give you a set of their old stock injectors for free. They are also widely available in junkyards. All you have to do is have them cleaned and balanced, which still winds up being a lot cheaper than buying 4 new equivalent flowing high impedance injectors.

http://www.nalanda.nitc.ac.in/industry/appnotes/IR/ASSETS/5SWITCH/HEXFET/IRLI530N.PDF

That is the injector driver. On the first page it says "ID = 11A". It can handle an 11 amp drain, which means that it is able to drive the DSM injectors wired in SERIES without any resistors. Corbin, you were right.

BUT (there's always one)

The injector drivers in the 034EFI are NOT heat sinked to anything, so I am going to add a heat sink seeing as how I'm going to be passing about 30 watts through each of the injector drivers. I don't know why a heat sink wasn't there to begin with - if I designed the thing I would have at least anchored the things to the metal casing, which would have been really quick, simple, and inexpensive.

Originally posted by ner947
Some 4G63 owners will give you a set of their old stock injectors for free. They are also widely available in junkyards. All you have to do is have them cleaned and balanced, which still winds up being a lot cheaper than buying 4 new equivalent flowing high impedance injectors.

Forgive me for butting in, but stock Turbo DSM injectors are low impedance.

Originally posted by HRC
Forgive me for butting in, but stock Turbo DSM injectors are low impedance.

On the 034EFI Extra injector controller, that is easy to work around.

Originally posted by Corbin
Anyone starting an 8 injector project should certainly pay attention to what they install. They will have to understand the implications involved with every part substitution. What about running two DSM 450's in series on each driver? That should still give acceptable power consumption. Corbin '95 ESI-T HRC+FMIC+ETC... Gimme fuel...Gimme fire...Gimme that which I desire

Come on now... injectors should never be run in series! :nono

I'm a ME, so you'll have to explain the EE stuff to me. How is running two injectors in series different than running one injector in series with a resistor? Personally, I don't think I'd be comfortable with either.

Corbin

'95 ESI-T
HRC+FMIC+ETC...



Gimme fuel...Gimme fire...Gimme that which I desire

Not to bash, but it seems odd to wire two solenoids in series that you wish simultaneous action and behavior from. Tyically, such desired simultaneous action would call for symmetrical circuitry, as in parallel (which WON'T work, way low impedance then!), or some type of relay or driver system that is identical for each injector, fired by a single pulse.

Keep in mind, it isn't so much the electrical part of this that seems incorrect...Ohm's law's are irrefutable...but the mechanical action of the way each of the two injectors would behave. With such precision required at high RPM and its short available duty cycle, there could be instability issues insofar as symmetrical fuel delivery.

Originally posted by HRC
Not to bash, but it seems odd to wire two solenoids in series that you wish simultaneous action and behavior from. Tyically, such desired simultaneous action would call for symmetrical circuitry, as in parallel (which WON'T work, way low impedance then!), or some type of relay or driver system that is identical for each injector, fired by a single pulse. Keep in mind, it isn't so much the electrical part of this that seems incorrect...Ohm's law's are irrefutable...but the mechanical action of the way each of the two injectors would behave. With such precision required at high RPM and its short available duty cycle, there could be instability issues insofar as symmetrical fuel delivery.

Exactly Bill!
You pretty much just explained why you cannot wire two injectors in series and expect them to operate reliably...

Wow its nice to see Mr. Hahn cheking on our posts...

Interesting read here... still feel the best option although more expensive is going with accell high impedance...(i mean common you allready spent so much you dont want to spend an extra 100 on injectors??

I think I've thought about it enough that I would no longer suggest that a person attempt it. However, neither of you has given a concrete reason why it wouldn't work just fine. I'm waiting for something like "the oscillation of the mechanical portions of the injector will alter the effective resistance of the injector coil...causing the voltage drop across the other injector coil to be altered...ultimately affecting the mechanical behavior of the aforementioned injector". Is this what you guys are getting at or is it something else?

Corbin

'95 ESI-T
HRC+FMIC+ETC...



Gimme fuel...Gimme fire...Gimme that which I desire

This is an interesting thread.

Looks like if I'm going to use the DSM injectors, they will be going in in parallell with a resistor in there so it won't draw too much current.

Then again, I'm considering using my high impedence 415 cc/min injectors as secondaries and putting the stock injectors back in as primaries, because it would be a hell of a lot easier to tune so I can get to the shootout. Looks like the DSM injectors as secondaries and my old 415's as primaries will have to wait for the winter when I have more time to experiment. Besides, there's no way I could ever need more than 650 cc/min to each cylinder with just a 16G...

Originally posted by ner947
Besides, there's no way I could ever need more than 650 cc/min to each cylinder with just a 16G...

Exactly. I have 610 cc/min per cylinder and that's plenty for 18+ psi on the s16g. But it's time to upgrade.

Something that nobody has figured out (or at least I have not seen it) would be the max time in MS that the 034EIC (or any eic for that matter) could hold the injectors open at max RPM. Let's say 7000 RPM in this case. Someone correct me if I am wrong...

60,000 / 7000 (RPM) = 8.5ms

So 8.5ms = 100% and 7.225ms = 85%

Great, I only have 7.2ms to fuel the cylinder at max rpm. Looks like it's already time for larger injectors. :twitch I don't mean to derail the thread, but this is something I've been meaning to run past you guys and this seemed like a good place to do it.


Bill Jr. - Thanks for getting those 'Gaskets' out to me so quick. ;) The rest of the package is a secret. :D

Originally posted by etx

Originally posted by ner947 Besides, there's no way I could ever need more than 650 cc/min to each cylinder with just a 16G...

Exactly. I have 610 cc/min per cylinder and that's plenty for 18+ psi on the s16g. But it's time to upgrade. Something that nobody has figured out (or at least I have not seen it) would be the max time in MS that the 034EIC (or any eic for that matter) could hold the injectors open at max RPM. Let's say 7000 RPM in this case. Someone correct me if I am wrong... 60,000 / 7000 (RPM) = 8.5ms So 8.5ms = 100% and 7.225ms = 85% Great, I only have 7.2ms to fuel the cylinder at max rpm. Looks like it's already time for larger injectors. :twitch I don't mean to derail the thread, but this is something I've been meaning to run past you guys and this seemed like a good place to do it. Bill Jr. - Thanks for getting those 'Gaskets' out to me so quick. ;) The rest of the package is a secret. :D

I know what it is... I know what it is... LOL but it's all good... I can keep a secret...

Ok... etx:

Your injector opening times are about right... however you also have to afactor in the injector opening time. An average injector opening time is arouns 1.0ms... so you have to factor that into the equation... that's why it is suggested not to go over 85% duty cycle... because of the opening time.... but, and there is a big BUT... this is assuming that you only want to be open for one revolution... when in reality on a 4 stroke engine you have 2 complete crank revolutions in which to work... so you can see the pw window is really twice the 8.5ms... and trust me... it really is OK to be injecting for more than one revolution at 6000rpm... the fuel WILL be ingested next time the intake valve opens... think about it... how long is the intake valve open at 6000rpm? It's less than 8.5ms... ;)

That is the reason that even a sequential fire injection system HAS to be in batch fire at high rpm to be able to inject enough fuel into the intake... ;)

Ok, now onto Corbin:

The reasons for not wanting to wire injectors in series are pretty real.
First, an injector is a electromagnetic soleniod at heart... and any time you open and close a solenoid you will get voltage spikes and noise... not as bad on DC as on an AC solenoid... but you will get noise. Now would we want noise on our injectors? No... probably not... ;)
Next reason in the injector opening time. If you put two injectors in series you then double the resistance in the circuit, and halve the available current to each injector.
The last reason I can think of right now is the injector opening time may now no longer be valid when you have the injectors in series.

Ok... that's about it for now... ;)
Oh... and there will be no problem using DSM injectors with the "correct" resistors in series... either on the 034 or on the stock ecu. ;)

Peace.

Originally posted by MrSlick
...If you put two injectors in series you then double the resistance in the circuit, and halve the available current to each injector...

Lee,

Sorry to split hairs... But, putting 2 injectors in series will half the voltage to each injector (assuming that they are both the same resistance) not half the current.

Thanks, the Management.

Originally posted by ner947

Originally posted by MrSlick ...If you put two injectors in series you then double the resistance in the circuit, and halve the available current to each injector...

Lee, Sorry to split hairs... But, putting 2 injectors in series will half the voltage to each injector (assuming that they are both the same resistance) not half the current. Thanks, the Management.

Hmmm. I disagree... again injectors are like solenoids/relays.
At work here in ours electrical cabinets we wire contactors in series. (It's ok we put quencharcs on them to control noise) Anyway you can measure the voltage at any one contactor coil and the voltage will not be reduced... ;) Just an example.

Lee...

I'm going to nit pick too. I'm siding with Nate on this one. Refer to the pic below:



That is Kirchhoff's current law and voltage law. Elements "A", "B", and "C" are resistive elements (could be resistors or injector coils). You will see that the elements are in series, just like the injectors in this discussion. The current is the same in each element. This is true no matter how many elements you place in series. You will also see that the voltage is cumulative between the elements. Adding elements alters the voltage drop across the other elements. So, in our discussion, the two series injectors will have the same current, but each will have exactly half the voltage drop of the driver circuit.

I think once the injectors start firing, there will be some interaction between them. I think most of it will boil down to changes in coil resistance due to the movement of the mechanical parts or the frequency of the signal. As for how much of a change...only experimentation will tell.

Originally posted by MrSlick

Originally posted by ner947

Originally posted by MrSlick ...If you put two injectors in series you then double the resistance in the circuit, and halve the available current to each injector...

Lee, Sorry to split hairs... But, putting 2 injectors in series will half the voltage to each injector (assuming that they are both the same resistance) not half the current. Thanks, the Management.

Hmmm. I disagree... again injectors are like solenoids/relays. At work here in ours electrical cabinets we wire contactors in series. (It's ok we put quencharcs on them to control noise) Anyway you can measure the voltage at any one contactor coil and the voltage will not be reduced... ;) Just an example.

Corbin

'95 ESI-T
HRC+FMIC+ETC...



Gimme fuel...Gimme fire...Gimme that which I desire

Originally posted by Corbin
Lee... I'm going to nit pick too. I'm siding with Nate on this one. Refer to the pic below: That is Kirchhoff's current law and voltage law. Elements "A", "B", and "C" are resistive elements (could be resistors or injector coils). You will see that the elements are in series, just like the injectors in this discussion. The current is the same in each element. This is true no matter how many elements you place in series. You will also see that the voltage is cumulative between the elements. Adding elements alters the voltage drop across the other elements. So, in our discussion, the two series injectors will have the same current, but each will have exactly half the voltage drop of the driver circuit. I think once the injectors start firing, there will be some interaction between them. I think most of it will boil down to changes in coil resistance due to the movement of the mechanical parts or the frequency of the signal. As for how much of a change...only experimentation will tell.

Originally posted by MrSlick

Originally posted by ner947

Originally posted by MrSlick ...If you put two injectors in series you then double the resistance in the circuit, and halve the available current to each injector...

Lee, Sorry to split hairs... But, putting 2 injectors in series will half the voltage to each injector (assuming that they are both the same resistance) not half the current. Thanks, the Management.

Hmmm. I disagree... again injectors are like solenoids/relays. At work here in ours electrical cabinets we wire contactors in series. (It's ok we put quencharcs on them to control noise) Anyway you can measure the voltage at any one contactor coil and the voltage will not be reduced... ;) Just an example.

Corbin '95 ESI-T HRC+FMIC+ETC... Gimme fuel...Gimme fire...Gimme that which I desire

So my brain is fried today... lol I just had things a little backwards... ;) Still, it's all more proof of why I say not to wire injectors in series...

Originally posted by Corbin
...or the frequency of the signal. As for how much of a change...only experimentation will tell.

I can measure the resistance of anything from 300kHz to 3GHz... Somehow I don't think that's the range of a fuel injector. :twitch Oh well.

Originally posted by Corbin
I think I've thought about it enough that I would no longer suggest that a person attempt it. However, neither of you has given a concrete reason why it wouldn't work just fine. I'm waiting for something like "the oscillation of the mechanical portions of the injector will alter the effective resistance of the injector coil...causing the voltage drop across the other injector coil to be altered...ultimately affecting the mechanical behavior of the aforementioned injector". Is this what you guys are getting at or is it something else? Corbin '95 ESI-T HRC+FMIC+ETC... Gimme fuel...Gimme fire...Gimme that which I desire

EDIT: As I posted this, I then saw MrSlick just posted before me with much of the same info, so forgive this if it seems repetitive. -Bill

I think what we are alluding to is the possibility that the mechanical action of the two series wired injectors would not be symmetrical, esp. in a Direct Current application. I see there being different behaviors in the two regarding solenoid winding rise time and actual mechanical point where pintile leaves seat (the beginning of injector pulse width). Yes, electricity moves at the speed of light, but injector internal components do not. Having one ahead of the other in a DC circuit seems wrong, at least insofar as the precision required that all injectors open and close at the exact same pulse width, which is not only a function of impedance vs. time (pulse width), but also of rise voltage and inherent opening delay...

Consider an injector that is open for 4MS, an average pulse width. That means it is open for .004 second. Four thousandths of a second. If its behavior were affected say 10% (enough to cause a significant difference in fuel flow, 10% can be the difference between perfect power and perfect destruction), that would be .0004 of a second. Thus, four ten thousanths of a second difference in injector opening event could cause problems. That is a difference so small that you could fit 2500 of them into one second. With a window of acceptable error that is so small, we simply must always strive to have each injector mirror its couterparts as much as possible.

I guess there's only one way to find out.

I'll hook up my 034EFI to some fuel injectors wired in series, and then in parallel, and I'll look at the waveform across the injector pins on a scope. It would be interesting to see the difference between what the 034EFI says it thinks the pulsewidth is vs. what the actual waveform looks like at the injector.

"Real questions. Real answers."

Originally posted by ner947
"Real questions. Real answers."

:D :D :D :D :D :D

Get to work and report back Nate! ;) I just got the head back from the machine shop and I will have some DSM injectors on the way shortly. I'm shooting to have the 2gnt back togeather this weekend for two days of street tuning and one day at the track before the Shootout weekend.

edit:

Originally posted by MrSlick
I know what it is... I know what it is... LOL but it's all good... I can keep a secret...

Heh, Ok secret is out! He is also going to resurface my manifold. ;)

Originally posted by etx
Get to work and report back Nate! ;) I just got the head back from the machine shop and I will have some DSM injectors on the way shortly. I'm shooting to have the 2gnt back togeather this weekend for two days of street tuning and one day at the track before the Shootout weekend. edit:

Originally posted by MrSlick I know what it is... I know what it is... LOL but it's all good... I can keep a secret...

Heh, Ok secret is out! He is also going to resurface my manifold. ;)

etx... I was referring to the rest of your package... ;)

Voltage in a series circuit is distributed among the devices(injectors), in that circuit, according to their resistance. The sum of the individual voltage drops in a series circuit must be equal to the applied voltage. (taken from literature)

Back in my car stereo days, and wiring amps and speakers, its known that when you connect a resistance(injector coils) in parallel, it halves the impedance, but voltage stays constant(er, depending on the current being drawn). Connect the resistances in series, impedance is doubled, but voltage does not stay constant, and you will get a certain amount of voltage drop accrooss each resistance, depending on its impedance.

Originally posted by XtremeRS
Voltage in a series circuit is distributed among the devices(injectors), in that circuit, according to their resistance. The sum of the individual voltage drops in a series circuit must be equal to the applied voltage. (taken from literature) Back in my car stereo days, and wiring amps and speakers, its known that when you connect a resistance(injector coils) in parallel, it halves the impedance, but voltage stays constant(er, depending on the current being drawn). Connect the resistances in series, impedance is doubled, but voltage does not stay constant, and you will get a certain amount of voltage drop accrooss each resistance, depending on its impedance.

I know... I was being half retarded earlier... haha.
Now I'm home and relaxed I'm like wait a minute... why did I get it backwards....lol