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Old 07-22-2011, 10:20 PM   #1
samo22
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Default DW Provided Injector Latency Data

I wanted to know what other people are doing for the injector latency for DW 750cc injectors. Mine came with the flow and latency data. Average flow is 747cc and the latency data as follows:

(volts/millisec) 7/3.3, 8/2.6, 9/2.2, 10/2.0, 11/1.8, 12/1.6, 13/1.5, 14/1.4, 15/1.3, 16/1.2, 17/1.1.

Also I found this table online that DW recommends for Subaru:

http://forums.nasioc.com/forums/show...02&postcount=2

Which is more recommended?

By the way, I scaled the injector to 650cc and the afr learning is around 3.7% and afr correction bounce around 0-.8%. Is this good enough?
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Old 07-24-2011, 10:56 AM   #2
jaxscuby
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Quote:
Originally Posted by samo22 View Post
By the way, I scaled the injector to 650cc and the afr learning is around 3.7% and afr correction bounce around 0-.8%. Is this good enough?
yes, you did a good job.
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Old 07-25-2011, 10:58 AM   #3
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I have never seen 750's scale as 650's

Also, you have to correctly interpret the data that DW provided. You'll notice that the OEM latency provided on their sheet is significantly higher than whats in a stock rom.

DW took the stock injectors and tested them using their method....then tested the modded 750's using the same method...so you are more interested in teh delta row than the actual latency row.

You want the delta from stock to modded. You can either just add that delta to the stock latency or to be more accurate you would convert it to a % then add that percent to the stock latencies in the rom.

stock rom has 0.68 at 14v

so you can either do 0.68+0.08 = 0.76

or (0.08/1.16)*100 = 7% so 0.68*1.07 = 0.73
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Old 07-25-2011, 01:16 PM   #4
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ah I see, so I need to look at the delta. Thanks for clearing that up for me!

Well for the scaling it to 650cc, I saw threads with people scaling them to 680 and even 650cc, but also found this post saying that they probably used the stock latency:

http://forums.nasioc.com/forums/show...7&postcount=20

I will update the latency and scale. Thanks!
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Old 07-25-2011, 01:20 PM   #5
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well...to tell if your scale is off you would do a WOT pull in 2nd gear....with the scaling at 650cc you would run about 15% rich.

The latency only effects low MAFv....less than 2 Mafv

for DW injectors my process is pretty simple.

type in the exact scalar....use the lowest value on the flowsheet

dial in the idle by changing the latency. 99% of the time this is an increase in latency....so its pretty straightforward

Make the rest of the changes (fine tuning) via the MAF scale.
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Old 07-25-2011, 01:40 PM   #6
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Ok, Thanks! I was thinking that I can just leave the MAF scale alone since I have a stock box, but I will log and verify/change accordingly.
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Old 07-25-2011, 01:50 PM   #7
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thats why i put (fine tuning)

people have this misconception that you can just throw in injectors and not change the maf. thats not true.

when i tune stage1 and stage2 cars on the stock box i still make changes to the MAF scale.
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Old 07-25-2011, 04:24 PM   #8
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Wow the jump between 6v and 7v delta is huge. For delta latency of 6.5V, the DW provides 6V delta of .96 and 7V delta of -0.16, so by averaging it 6.5V delta = (.96+(-.16))/2 = .4?
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Old 07-25-2011, 04:48 PM   #9
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It makes it easier if u do it graphically in excel.....but I wouldn't be too anal about those values unless u plan on running on dying batteries
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Old 07-25-2011, 05:08 PM   #10
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Phatron........why wouldnt you want to change the values to be the same at all voltage? That way itll run the same all the time any voltage no matter what. Just wondering, thats all. I just dont understand when the vehicle would be running at 6 or 7 volts and need the latencies to be changed solely on alternator output voltage.
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Old 07-25-2011, 05:20 PM   #11
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because the injector isnt going to spray the same amount of fuel at 6v as it does at 14v......think of the kenne bell boost a pump. it increases the voltage to the fuel pump to make it flow more, same concept here

basically what the latency is doing is exactly what you said.....trying to make it spray the same at all voltages.
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Old 07-25-2011, 05:32 PM   #12
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ahhhh got ya! Thanks!!
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Old 07-25-2011, 06:42 PM   #13
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Sweet, I got AF learning 1.56% with injectors scaled at 745 and latency of

3.14 1.75 1.2 .86 .46

I'm going to log around, but my laptop battery is out lol, I guess I didn't have to play with it for such a long time.
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Old 07-26-2011, 02:37 AM   #14
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Well I drove around logging my car and plotted AF correction #1 VS MAFv, and the AF correction increases as the MAFv increases, and around 2.2V, the correction is as high as 15 to 20%. I checked the fuel trims in learning view, and its at -2.34, .10, .59, 0. I am guessing that I need to drive around more to settle some of the fuel trims. But wouldn't the fuel trims converge to 15% or so if I'm seeing AF correction of 15%? Am I supposed to reduce the % by adjusting the MAF scale?
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Old 01-05-2015, 09:15 PM   #15
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any other injectors sizes?..ie..larger ones since DW didn't send the information for +1000cc's
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