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Old 03-28-2013, 02:37 AM   #81
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Quote:
Originally Posted by Braineack View Post
lol at having to idle at 12:1 with slightly larger than stock injectors. DW injectors are awesome!
Yeah, I was pretty eager to believe that the published times were incorrect, especially after looking at some of the latencies of similar and even much larger injectors which had lower times. But sadly, it appears that the specs are correct and the injectors are just slow. I can probably idle them higher, but 12 seemed very stable and I want to get the rest of the tune sorted out before trying to push the minimum limits of these injectors. (That just sounds idiotic for such comparatively small injectors.)

Last edited by jnshk; 03-28-2013 at 02:39 AM. Reason: Why did the body of my message suddenly vanish?
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Old 04-24-2013, 04:43 PM   #82
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Anyone happen to know the info for 23250 42010 430cc 7mgte denso injectors?
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Old 04-24-2013, 06:16 PM   #83
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Came up with 1.218 for a set of ID 1000

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Old 04-26-2013, 01:02 PM   #84
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Old 02-09-2014, 09:22 PM   #85
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Quote:
Originally Posted by midpack View Post
Came up with 1.218 for a set of ID 1000
Those are very similar numbers to what I measured with my ID725s. Quite different to the published specs!

Do you think our cars potentially have a lower voltage at the injectors than at the ECU?

If I use the published specs for the injector then the VE table ramps up rapidly in the low load rows of the table, using the measured value flattens it out nicely but then seems to be pig rich for some overrun conditions.

Any ideas?
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Old 07-21-2014, 05:34 PM   #86
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Quote:
Originally Posted by JasonC SBB View Post
Bummer, looks like your injectors have 2 distinct slopes. A shallower one, with an effective dead time of ~1.5 ms (eyeballing it), at smaller PW's, and a steeper one starting at about 1.85 ms of electrical pulse width, with about 0.9 ms effective dead time.

For idle stability I'd use the 1.5 ms number. This would mean the VE table entries in the range of 2-2.5 ms would need adjusting.

I saw a paper out there that describes how OEs program a dual-slope deadtime like this. It's actually described in some OE injector datasheets.
That's how Ford calculates it. There is a high slope, low slope, and a breakpoint. The breakpoint being where it switches from low slope to high slope.

All injectors will have a non-linear and linear operating range. The non-linear range is in the lower pulse-widths and tends to be where the low slope's line is generated from that data range.

Last edited by LowFlyin'; 07-22-2014 at 11:54 AM. Reason: brake point? lol
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Old 07-22-2014, 11:45 AM   #87
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One very common mistake is that because often the latency spec given by manufacturers for a given fuel pressure is for the injectors squirting in to test tubes with the injector outlet at atmospheric pressures. Because latency is most important at idle, at which the nozzles see ~35 kPa (- 10 psi), you should look up the latency at:

your fuel pressure + 10 psi
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Old 07-25-2014, 01:46 AM   #88
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How about this?
I'm sure most that have access to a scope know this but if you didn't, here you go.
This is a Pico scope hooked to an injector wire using a low amp current probe.

You see zero current on the left and then when the injector is switched on it begins to ramp up. I placed the first marker here.

Notice the bump in the ramp. This is where the pintle moves and changes the flow of current slightly.

The straight down drop is when the injector is turned off.

The box in the top of the screen is showing where I placed the markers. The first marker to the second is 1.389 ms. I am unclear on if the first "dip" or the second (which I have marked) is actual dead time. Could be some where in between? I highly doubt the injector is flowing "fully" at the first dip as the pintle has just begun to move.

Total "on time" here is about 2.8ms. (Idle)

This is just a stock 265cc/hr 1.8L injector at stock fuel pressure.
I know everyone doesn't have a oscilloscope at their disposal, but if you do, check it out. I wonder how this compairs to the other method described in this thread.

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How to find your injector dead time-2dc335d3-c407-4caf-a3b9-ce34a941ecb9.jpg  
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Old 07-25-2014, 12:14 PM   #89
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When we were including latency data with our injector, the method above is how it was collected.

Oscilloscope, direct trigger, pressure. Read the graphed data and average 10 results.

We've stepped away from just providing latency data as many of the current ECU's are asking for more injector data.
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Old 07-25-2014, 10:49 PM   #90
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Quote:
Originally Posted by LowFlyin' View Post
When we were including latency data with our injector, the method above is how it was collected.

Oscilloscope, direct trigger, pressure. Read the graphed data and average 10 results.

We've stepped away from just providing latency data as many of the current ECU's are asking for more injector data.
So what do you say is latency in my pic? Where I have the markers? Or move the second marker to the left between the first and second dip? The first dip?

Just seems that 1.3ms is a little slow, but hey, they're stock.
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Old 08-27-2014, 10:48 AM   #91
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I tried several things and i really dont get it.. here is my datalog, first i did a little run to warm the car up and then i did the trick in megasquirt with the pw ms up and down

Is my datalog clean to perform this trick

My injectors are the yellow RX-8 injectors
Attached Files
File Type: msl 2014-08-27_15_modified.msl (1.73 MB, 98 views)
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