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Old 05-14-2015, 09:18 AM   #1
Dirty Rick
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Default Injector dead time

Changing injectors to a 0-280-155-831

I can't seem to find published data for the injector dead time. Or voltage curve.

I have heard some speak of switching from 2 squirts to 4 squirts and observing the change in AFR.

Any guidance? Or links?
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Old 05-18-2015, 07:55 AM   #2
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Google? If you mean latentcy, there are lots of things that can effect if. Dead time seems to come from the asian tuner world vocabulary. In GM tuning it's called injector offset. You should really research harder, because your asking an ambiguous question, MAF calibration, and injector changes usually go hand in hand, if you don't have a way to change calibration, you may be pissing away money.
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Old 05-18-2015, 08:59 AM   #3
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I posted in wrong section, should have been in aftermarket engine managment. I have discovered that "dead time" (opening and closing time) is relevant to getting a good idle as the voltage changes from accys will affect AFR's at low engine speeds when the alternator is not able to compensate.
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Old 05-18-2015, 02:35 PM   #4
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Originally Posted by Dirty Rick View Post
Changing injectors to a 0-280-155-831

I can't seem to find published data for the injector dead time. Or voltage curve.

I have heard some speak of switching from 2 squirts to 4 squirts and observing the change in AFR.

Any guidance? Or links?
I'm running these and on a stock lh2.4 system they will run fine in closed loop, but entirely too rich in boost without tuning. There's also conflicting opinions about how much these flow, since in some charts they are listed as flowing 32lb/hr @ 4bar, but on the stock 3bar fpr they should flow less than stock greentops... but they definitely will make the car run richer if left untuned.

I'm not sure on the dead time, but changing the sizing alone in the ecu makes them run fine, and idle is great.
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Old 05-19-2015, 01:37 AM   #5
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Injector deadtime in MS is an approximation of the time that the injector is powered but isn't injecting [much] fuel. For high flow injectors, this matters because low-flow idle needs accurate compensation, or closed-loop idle control, or else idle is bad.

In theory, changing squirts from 2 to 4 should have the same AFR if the deadtime compensation is correct. There's the a new thread with some practical comments at msextra:
http://www.msextra.com/forums/viewto...?f=131&t=58316.

For your injectors, a google search of "0280155831 deadtime" says 0.455ms but the few links I tried didn't really list a believable deadtime, or voltage compensation number.
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Old 10-15-2015, 01:53 AM   #6
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Has there been some progress on this? I may have to throw them on a flownench and see for myself. The .450 mS figure seems to be exactly half the dead time one would expect for a high z injector.

For reference, using these injectors my settings are .950 mS and .160 mS/V for voltage delta, and it's been working pretty well for the most part. I get a 0.5:1 AFR swing between morning and evening (so between 55 and 85 degrees) but that may be due to the MAT correction curve being overly aggressive out of the box.
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Old 10-15-2015, 02:40 AM   #7
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Old 10-15-2015, 07:38 AM   #8
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so this is what we can expect from now on, monkey has new toy. a scope does not tell you if the flow through the injector has stabilized regardless of what the field in the coil is doing. There's several threads over on msextra that talk about determining opening time for unknown injectors, but one can also extrapolate information from a given age and family of injectors (as they tend to be very close).
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Old 10-15-2015, 08:50 AM   #9
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As Kenny already pointed out, the spike you see there is because the collapsing magnetic field in the coil inside the injector is inducing a current. That would happen even if the injector would be mechanically stuck shut. The opening and closing delays are more of a mechanical phenomena.
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Old 10-15-2015, 09:36 AM   #10
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Originally Posted by Dirty Rick View Post
Any guidance? Or links?
I find this quite humorous, Coming from the guy who claims to know more about engine management than anyone on this forum because they've dropped names of long forgotten drag racers. Oh, and NASA too.

Thought you'd already know how to figure this out, rocket scientist.
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Old 10-15-2015, 09:54 AM   #11
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So roughly .8ms on this one, given the initial spike until the pintle actually opens. Got a part number though?
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Old 10-15-2015, 10:22 AM   #12
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Originally Posted by gsellstr View Post
So roughly .8ms on this one, given the initial spike until the pintle actually opens. Got a part number though?

depends on whether or not the flow through the injector has stabilized. in extremely low pulsewidth situations (not likely to happen with 330cc@5bar injectors) fuel flow can do different things, again look up the thread about it on msextra, there's a lot of good info there. I think it's stickied over there.

anywhere from .8 to 1.2 is a good starting point for most older injectors.
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Old 10-15-2015, 10:31 AM   #13
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Agreed. Think I'm at .95 on the Delphi's in the wagon, 1.15 on the d-jet 036's in the 140.
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Old 10-15-2015, 10:36 AM   #14
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http://automotivetestsolutions.com/u...waveforms.html
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Old 10-15-2015, 10:55 AM   #15
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...

Last edited by ZVOLV; 10-15-2015 at 11:06 AM.. Reason: because labscopes are cool
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Old 10-15-2015, 11:17 AM   #16
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It's funny you view things that way(though I'm sure I'm on the ignore list, as you have a comical habit of blocking people with more experience than yourself). talking about an individual tool is hardly akin to talking about religion, though I guess it's a good thing you finally discovered oscilloscopes and their myriad uses. Not everyone has one (although, much like many other tools, they are irreplaceable when the time comes), and for the particular situation there are well documented methods to get the value requested without one, and again, there is time after voltage stabilization before fuel flow stabilizes. You don't have to simply trust me on this, it's well documented in the aftermarket world.

http://www.msextra.com/forums/viewto...?f=131&t=41357

just a little food for thought. not everything scopes out perfectly. Incidentally, what's the scope going to tell you if the basket is clogged? no fuel flow, however the pintle moves causing the expected output to show up on the scope.
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Old 10-15-2015, 11:22 AM   #17
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"This message is hidden because linuxman51 is on your ignore list."

I disrespect you.
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Old 10-15-2015, 11:32 AM   #18
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"This message is hidden because linuxman51 is on your ignore list."

I disrespect you.

You disrespect me. Well then. Somehow that's comforting, actually. For the larger crowd, I channel the ageless Eric Simpson "Some of us actually do these things". I leave it up to the crowd to decide if they should listen to people that have accomplished something (of which there are many to choose from, I certainly don't think of myself as being all alone at the pinnacle of something-there are plenty of other people who've gone faster, had nicer looking stuff, and there will hopefully be plenty to come behind us doing it better than we have), or people who flap their keyboards and try and dazzle others with bull**** and buzzwords.
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Old 10-15-2015, 11:48 AM   #19
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"This message is hidden because linuxman51 is on your ignore list."

I disrespect you.
You're gonna be missin out on some sweet tractor pictures bub
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Old 10-15-2015, 11:50 AM   #20
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You're gonna be missin out on some sweet tractor pictures bub
and shop n00dz if I can get any of these contractors to call me back :sigh:
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Old 10-15-2015, 11:53 AM   #21
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As Kenny already pointed out, the spike you see there is because the collapsing magnetic field in the coil inside the injector is inducing a current. That would happen even if the injector would be mechanically stuck shut. The opening and closing delays are more of a mechanical phenomena.
Not exactly, but close enough for practical purposes. When the field collapeses in some instances, where the pintle is stuck, the view on the scope will be slightly different. Very similar to this, but when you scope other injectors on the same vehicle you will see the difference.

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and shop n00dz if I can get any of these contractors to call me back :sigh:
If that's the case I'm going to have to ignore you too Kenny.
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Old 10-15-2015, 11:54 AM   #22
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I like n00dz.
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Old 10-15-2015, 11:59 AM   #23
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"This message is hidden because linuxman51 is on your ignore list."

I disrespect you.
lololol You almost cut me with your edginess, bruh

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and shop n00dz if I can get any of these contractors to call me back :sigh:
What do n00dz like like through a scope?
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Old 10-15-2015, 12:03 PM   #24
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Last edited by ZVOLV; 10-15-2015 at 12:24 PM.. Reason: post is below. Meant to edit....damnit.
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Old 10-15-2015, 12:24 PM   #25
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