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Old 06-18-2012, 10:43 PM   #10
Scooby Specialist
Member#: 73932
Join Date: Nov 2004
Chapter/Region: RMIC
Location: Denver
2005 STi BROtuned
2004 S2000


Originally Posted by juanmedina View Post
The car shutting off when going from cruising to neutral happen because the MAF is scaled to low (loads < 3g/rev)

What CAI are you running? Blow through?

Your pump should be able to handle the fueling all they way to 500whp dynojet and there is not way you are maxing out the stock fuel lines.
I have scaled and scaled the MAF to a point where I could not believe the trouble. This later led me to question a boost leak with the 40ft of piping newly assembled under the hood. I found quite a few boost leaks and tightened the T-bolt clamps until they no longer leak. One of them... I tightened enough to get the clamp to start pushing into the thing aluminum piping. Part of the easy leaking is due to the fact Treadstones hoses are just too large in diameter.

Still seeing issues, I tested again and found that a couple vacuum lines would leak and the recently installed Grimmspeed TGV-to-intake gaskets were leaking pretty bad. At that point, I had the car for about 2 weeks and threw in the towel after finding that I had put a dent in the piping (still feel horrible).

Originally Posted by Layvon View Post
These were my first two questions. If it is not blow through, that is a bonus, but if the MAF is on a funky angle, or just coming off a corner, that will most certainly affect the way it is reading. Is the MAF dirty?

How are you tuned? Open source?

If you're tuned w/ a cobb, you should consider speed density to see if that is part of the problem. There is a setting on there where it blends the two so you dont have to retune right away, but it doesn't sounds like getting a modified tune is a problem for you.

No vacuum leak? What about bad MAP sensor? Not a common fail point but ... never know. Simple enough to check

Good luck!
With the ID2200's and the MAF disconnected, I got the injectors to idle extremely well with and without A/C. It was almost a seemless transition from A/C on and off. As soon as we plug in the MAF, it would idle like poo (later found the leak at the TGV's).

Originally Posted by Nuke209 View Post
Check what the maf limit on the tune is set to. May need to raise it. Also what is the max maf voltage you are hitting
Without looking at a map, I think it was set to 500g/s.

Originally Posted by eliezerrosario View Post
Did you remove the stock fuel check valves when you did your fuel system? If so, that could be your problem. The check valves help keep fuel pressure from dropping off.
Are you talking about the little drum looking things next to the strut tower? Those aren't check valves.

My thoughts on the fuel pressure dropping this point is a few theories:

1 - Walbro 255 drops flow drastically nearing 70 PSI
2 - Factory wiring cannot support the demand and such a high demand (and is a personal though as to why a bigger pump didn't show any improvement).
3 - The stock top feed rails that were sent to us were a little bent. Looks like someone bent them back to get them off easier. I had to bend them into position to get them remounted. The lines looked okay to me, but if they are limiting more flow, depending where and how the re-bends are reacting, maybe that could be causing the fluctuation/drop.

CJ, Have you tried a new sock on the pump. It's a far out guess, but it's just another thought.
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