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Old 05-15-2008, 02:57 AM   #1
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Default Do these cranking setting seem right?

I am running 550cc injectors now, the first night I put them in I started the car up before going home and it started fine and idled fine (a whole 30sec), but the next day that I tried it seemed to flood out and wouldn't re-start. I decided to send the injectors out to get flow tested since they were used and the previous owner was acting shady about them, and they are 550cc after all. Do these cranking settings make sense? I just used the difference between the 230s and the 550s and adjusted the original cranking settings ( 550/230=2.39, original setting/2.39). I figured it would be close enough to start it but its only good for one cold start. Do these numbers seem unusually low or high? Stock on the left new settings on the right. I put them back in earlier tonight but didn't have the laptop so I will try again tomorrow.

:edit: Also req fuel is correct @ 5.5 although I just remembered I never changed the Injector Characteristics settings for low impedance but can't remember if I need to with a resistor pack.. Time to read the MegaManual on that one..
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Do these cranking setting seem right?-230550cpw.jpg   Do these cranking setting seem right?-550ec1.jpg  
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Old 05-15-2008, 07:45 AM   #2
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Pretty sure my PW tables is around 3.0 at 160 and scales up at a rate of like .2 ms per cell.
That is an ok starting place to tune it for your own car though.
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Old 05-15-2008, 09:22 AM   #3
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the table on the right is low.

i have been tweaking my 550 settings since last wednesday and they run a bit higher. i don't have my laptop in front of me, but with a 1.6 i start at 1.9 for the 160 bin, 2.0 for 130, and up... i want to say i'm in the 3.6 - 3.8 range by 60 and over 4.0 at 40, and even those take a little longer than i would like before the car fires, so a couple more tenths might be in order for me.

considering you're a 1.8 as well, yours might need to even be a little higher than mine.

i have a 5.7 req_fuel, i think, according to the calculator, using a 14.7 afr, and my 1k'ish idle PW when i'm warmed up is 1.6 - 1.7

i'll post my settings when i have my laptop in front of me again, though.
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Old 05-15-2008, 09:23 AM   #4
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oh, and if you have resistors inline for your injectors, you shouldn't need to mess with PW settings.
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Old 05-15-2008, 10:16 AM   #5
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at 40*F you may start seeing issues. the DIY table isn't tuned that low and you can see the jump back up. but all-in-all they look about right.
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Old 05-15-2008, 12:12 PM   #6
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They actually seem a tad low to me across the board. Here are my 465 settings:



(Obviously this hasn't been tested below ~50 or so.)

Thing about low-imp injectors with resistors in series is that, theoretically, they should have somewhat higher lag times than regular hi-imp injectors. Not that Req_Fuel and the other constants matter for cranking.
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Old 05-15-2008, 12:29 PM   #7
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my settings are pretty damn close to joe's, from memory.
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Old 05-15-2008, 12:38 PM   #8
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These work for me perfectly (tested to 43F); 460cc injectors and 5.9 Req_fuel.

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Old 05-15-2008, 01:13 PM   #9
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I think I spoke to Jerry about this, Cranking PW's are independent of ReqFuel value.
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Old 05-15-2008, 01:25 PM   #10
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no i don't believe they do. dunno why i added that

1ms for opening and closing time, the rest is simply how much you inject.
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Old 05-15-2008, 01:49 PM   #11
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if you can get the car running and record a warm idle PW, i posted the formula for calculating the hot and cold values in a thread awhile back.

it got me close, and just needed some tweaking from there.

https://www.miataturbo.net/forum/sho...57&postcount=7
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Old 05-15-2008, 02:56 PM   #12
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Hm so the general consensus is that they are close but a bit low. Is anyone else on here running 550s on a 1.8? I wonder how much of a difference the table is for a 1.6 w/550 vs 1.8 w/550. Hopefully i'll get something figured out tonight.
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Old 05-15-2008, 03:01 PM   #13
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instead of original / 2.29.

you need to subtrac 1ms out of the equation, because that's opening and closing time.

so example, lets use your 160F row:

3.1ms

550 / 230 = 2.39

3.1ms - 1ms = 2.1ms

2.1 / 2.39 = .87

.87 + 1 = 1.87

3.1ms will then = 1.87
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Old 05-15-2008, 05:35 PM   #14
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Thanks Braineack, I will give that one a try tonight, that makes alot more sense.
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Old 05-15-2008, 10:44 PM   #15
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Joes table is about exactly like mine.
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Old 05-16-2008, 12:39 AM   #16
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Re calculated the cranking settings taking into account the 1ms as Braineack said and it started up alot easier, I think that did it. I screwed up and forgot to reset my req fuel to 5.5 when I put the new settings in so I spent a while trying to figure out why I had to tune my VE way down so I still have to re do that but oh well, I have to learn some how.

Thanks guys!
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