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Old 02-12-2012, 06:47 PM   #201
langsbr
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Clark, I appreciate the response, but I also like to understand the "why" behind the answer?

Raising the fuel pressure doesn't mess up the tune? Do I need to rescale the maf? I'm sure my assumption could be incorrect, but I'd assume that with a higher base pressure, the injectors are now spraying more fuel all the time. Is that not the case? I am seeing nearly 10% correction in C learning view range, but nothing in D.

What am I missing in regards to the effect the higher base pressure has?
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Old 02-13-2012, 06:13 AM   #202
ride5000
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Quote:
Originally Posted by CZ03WRX View Post
my car is running lean because the static FPR is maxing out my stock pump.
what does that mean?
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Old 02-13-2012, 08:37 PM   #203
langsbr
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Quote:
Originally Posted by Clark Turner View Post
You wont change injector scale setting.

C
What would need to change then? I thought I had a decent grasp on this, but I must be missing something obvious.

You said in the original post you need to retune to prevent it from running rich.

I have a stock intake, and am thus running stock MAF scaling.

Injectors are stock JDM STI, and scaled to 552cc.

I'm really confused that the JDM STIs use a higher stock base pressure. If that's the case, wouldn't that mean they have larger than 550cc injectors, or the scaling is 550 WITH the pressure at 53, and not 43?

I would think one would have the injector scaling correct, and then scale the maf so that the OL target matches true AFR.

What am I missing?
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Old 02-16-2012, 01:24 AM   #204
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Can no one answer this? I can change the ol fuel map, but then wouldn't AFRs not be consistent or matching?

Also, if the jdm runs a higher base pressure, wouldn't that result in SUPER rich afrs? The stock map targets 9.8:1.
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Old 02-16-2012, 11:56 AM   #205
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I think the problem is nobody understands what you are asking man. You are asking for information about tuning I think but then again maybe not because this is a thread about a fuel pressure regulator.

The raise in pressure is only going to really effect wot. The effect on low MS is very minimal and as a result closed loop wont be change that much. You dont need to change the scaling. Most fuel pumps flow goes way way down as pressure goes up so gains are also minimal. Back when we had NO and I mean NO big injectors on the market this was a great mod. I used it all the time. I could stretch those 565s pinks out and when we started uncapping stock injectors, I could stretch those a bit farther with GT35R setups back in 2004.

Now we have larger injectors and you wont need to do this mod. As for the JDM regulator. I have seen about a thousand and some had a deeper dent in the top of the regulator as compared to others. It was just a small increase in base pressure. Its not a big deal. The stock map is a very low power map that runs very rich.

That help?

C
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Old 02-16-2012, 01:50 PM   #206
langsbr
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For the most part.

In effect, it's NOT that the JDM was truly running at a higher base pressure, it's just that they didn't have good quality control?

You stated in your other posts that WOT went from 11.5:1 to 9:1 by raising base pressure 10 psi.

You said you won't scale the injectors - so SOMETHING has to change in the tune.

Others have said you DO scale the injectors - other yet say the OL fueling map.

I don't see how confusing the question is -

If I up the base fuel pressure - what would I change in the ECU?

If it's the OL fueling map, won't that throw off the match of its target AFR to a wideband?

That was how I understood MAF scaling was done- at least that's what all the guides I've seen state.
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Old 02-27-2012, 09:44 PM   #207
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Default great thread

great work and thanks for all the juicy intel. This thread is bookmarked and revisited frequently. Thanks all.
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Old 09-16-2013, 02:19 AM   #208
Buffman
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I modded mine tonight. I was hitting 97% IDC with an 11.4 AFR on my 02 Stage 2 WRX. I tapped the indent in from .123" to .133" and gained roughly 10psi. My AFR's are now 10.4 and will be retuning in the morning.. Walbro pump of course.
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Old 07-18-2016, 12:13 PM   #209
teachrfly
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Default 98 2.2 fuel lines

Does anyone know which fuel lines are which under the rear seat in a 1998 Impreza
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Old 09-20-2019, 10:09 PM   #210
azhiaziamsubie
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not to resurrect this thread from the dead past but i am getting really confused with a lot of misinformation floating around on the forums.

If you ONLY change the Fuel Pressure Regular, why do you need a tune?

injectors same, rails same, pump same, etc, but i change the FPR, do i need a tune? and why?

if the FPR is still 1:1 and set for static pressure of 43.5psi, i dont understand why a tune is needed.

can anyone explain?
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