IW STi Forum banner
Cancel
Create thread New Garage Forums

Fuel rail kit or the stumble fix..

Engine
Jump to Latest
21 - 40 of 40 Posts
#21 ·
refujiado said:
K sounds good peeps, i also talked to Cobb and apparently on the 2015's is not much of an issue so... I think im headed towards the headers now... now the question is which... Tomei and Killer b are on the top of my list so lets see what i can acquire.
Click to expand...
Hit up Jake at jsauto he sold me my killer b's for $1325 and I would of had them in a month but things got delayed and he always kept me updated and they came in about 3 weeks after. Way faster than any other vendors I talked to.
 
#23 · (Edited)
#24 ·
i did have the 3 foot extension installed, and for a basic stage 2 tune it was useable. i have now switched to e85, and have found that the mod is no longer acceptable. fueling was all over the place. i will be swapping to the cobb fpr, which is more than enough for my needs. this was on a 2012 sti.
 
#25 ·
im running catless DP+cobb sf+1000cc injector+fuel pump upgrade, the car stumble very bad when cruising 70~75mph on hwy( AFR is over 17). then i assemble a FPR kit( pretty much the same as the one cobb offer, but half of the cost), no more stumble. and somehow reduce a lot of cruise knock
 
#27 ·
tomoya said:
im running catless DP+cobb sf+1000cc injector+fuel pump upgrade, the car stumble very bad when cruising 70~75mph on hwy( AFR is over 17). then i assemble a FPR kit( pretty much the same as the one cobb offer, but half of the cost), no more stumble. and somehow reduce a lot of cruise knock
Click to expand...

You'll noticed less cruise knock due to AF learning correction being smaller because it's running richer than before, i also installed the IAP kit on my car but from my experience I can actually just compensated using the Load compensation map without using the kit too.
I guess once you go bigger injector this kit might benefit lot more but on my stock injector it seem like a waste of money mod to me because i was able to fix the cruise knock with load compensation map alone and i never experienced the stumble on 2015 stage 2 cars.
 
#29 ·
3000gt-gto said:
You'll noticed less cruise knock due to AF learning correction being smaller because it's running richer than before, i also installed the IAP kit on my car but from my experience I can actually just compensated using the Load compensation map without using the kit too.

I guess once you go bigger injector this kit might benefit lot more but on my stock injector it seem like a waste of money mod to me because i was able to fix the cruise knock with load compensation map alone and i never experienced the stumble on 2015 stage 2 cars.
Click to expand...

My tuner said it wasn't necessary either with the stock injectors. He has it tuned out on mine at stage 2.
 
#30 · (Edited)
I've been gathering info regarding the Cobb Style, iaPerformance style Stumble Fix (GD Type Regulator) and so far, the feedback I've gotten from people who built and got it tuned says it works.

Stock injectors though, not larger injectors. I've been running my setup for about 6 months now with a tune from Eric@Torqued Performance and no more stumbles on my Stage2 setup.

I'm installing Equal Length Headers, and a Grimspeed Up-Pipe in a week or to and and I'm itching to install ID1000 injectors with my current setup to lower the IDC. Would be great if someone with the larger injectors can try it out (and get their setup tuned with someone who knows how to deal with this stuff).

http://www.iwsti.com/forums/diy-mod...-installations/274767-gr-stumble-mod-fix-gd-style-setup-not-hose-extension.html
 
#31 ·
funks said:
I've been gathering info regarding the Cobb Style, iaPerformance style Stumble Fix (GD Type Regulator) and so far, the feedback I've gotten from people who built and got it tuned says it works.

Stock injectors though, not larger injectors. I've been running my setup for about 6 months now with a tune from Eric@Torqued Performance and no more stumbles on my Stage2 setup.

I'm installing Equal Length Headers, and a Grimspeed Up-Pipe in a week or to and and I'm itching to install ID1000 injectors with my current setup to lower the IDC. Would be great if someone with the larger injectors can try it out (and get their setup tuned with someone who knows how to deal with this stuff).

http://www.iwsti.com/forums/diy-mod...-installations/274767-gr-stumble-mod-fix-gd-style-setup-not-hose-extension.html
Click to expand...

Sure it works but I think some tuners are able to tune it to lessen or negate it on the stock injectors. It's tuned out of mine on stage 2. Depends on your tuner.
 
#33 · (Edited)
Looks just like another fancy looking rail to me, why would people pay a whole bunch of money for something that looks pretty when one can't even see it. A parallel setup is basically just some CNC'd aluminum, and lines. A lot of people convince themselves that function is somehow tied to how expensive it is.

If you are gonna spend money on going parallel, then I suggest you spend your money on getting "really" good lines. If you have a good local shop that can bend and make hard lines, talk to em. Crappy lines, crappy fitment, rubbing, leaking lines == car fire. There's a reason why most OEM's use hard lines for fuel delivery, primarily durability, and better routing (no rubbing anywhere, not affected by vibration). The fuel rail is the least of your worries as those are usually built to tight specs using a CNC machine and it literally is just a piece of aluminum with a hole bored in the middle, 1 inlet port, 1 outlet port, and two ports for the injectors - can't really F that up.

If you really want fuel dampers, then you can easily add those inline before the rails, but most aftermarket fuel pressure regulators already have dampers, dampening effect..
 
#34 ·
StxSti said:
This is something new I found. They claim to have solved the problem.

Radium Engineering - Blog - New Product Release: Subaru Fuel Rails
Click to expand...
I like these rails. It's nice to have the dampers out of the way. I wish more people would get away from NPT threads and use ORB fittings. They are so much easier to install and are more compact for tight fitments.

funks said:
<snipped>If you are gonna spend money on going parallel, then I suggest you spend your money on getting "really" good lines. If you have a good local shop that can bend and make hard lines, talk to em. Crappy lines, crappy fitment, rubbing, leaking lines == car fire. There's a reason why most OEM's use hard lines for fuel delivery, primarily durability, and better routing (no rubbing anywhere, not affected by vibration). The fuel rail is the least of your worries as those are usually built to tight specs using a CNC machine and it literally is just a piece of aluminum with a hole bored in the middle, 1 inlet port, 1 outlet port, and two ports for the injectors - can't really F that up.

If you really want fuel dampers, then you can easily add those inline before the rails, but most aftermarket fuel pressure regulators already have dampers, dampening effect..
Click to expand...
I agree, hard lines are functionally better and look a ton better; it's difficult to find someone that can do this well. Teflon steel braided line is the next best option.

I'm not aware of any fuel pressure regulators that have built in dampers. Which one(s) are you referring to?
 
Save
Reply Quote Like Like
#35 · (Edited)
405HP_Z06 said:
I'm not aware of any fuel pressure regulators that have built in dampers. Which one(s) are you referring to?
Click to expand...
Aeromotive fuel pressure regulators have dampening capability built into the regulator. At least that's what Injector-Rehab says (Fuel Pulsation Damper)

Some quotes from Aeromotive technical staff

"The Aeromotive bypass fuel pressure regulator works to dampen pulsation and create a smooth, stable pressure. That is how it regulates. Given a correct installation, with recommended flow path through the fuel rail and to the regulator, and mounting the regulator close to the fuel rail outlet, there will be no need for any additional “damper”."
Click to expand...

 
#36 ·
funks said:
Aeromotive fuel pressure regulators have dampening capability built into the regulator. At least that's what Injector-Rehab says (Fuel Pulsation Damper)

Some quotes from Aeromotive technical staff


[/SIZE][/FONT][/B]
Click to expand...
I think the configuration Aeromotive talks about helps to reduce fuel pulsation. The regulators don't have an additional dampening mechanism within them; however, I can see in theory how the configuration and spring mounted diaphragm would help to reduce pulsation at the injector.

Good discussion. :)
 
Save
Reply Quote Like Like
#40 ·
refujiado said:
Who here has a stage 2 (injectors and pump) modded 2015 sti with the stumble issue ???
Click to expand...
My stock 15 didnt have the stumble till i went stage 2 + protune then hello stumble, i had installed the cobb fpr as a preventative maintenance to now find out that i have the stumble..sent logs to tuner, hopefully they find something and its not just me..
 
21 - 40 of 40 Posts
About this Discussion
39 Replies
23 Participants
Last post:
itsm3ming
IW STi Forum
posts
4.1M
members
124K
Since
2001
A forum community dedicated to Subaru Impreza and STI owners and enthusiasts. Come join the discussion about performance, engine builds, exhaust, modifications, troubleshooting, maintenance, and more!
Full Forum Listing
Explore Our Forums
GD-General 2.5 Liter/Litre Factory Motor GD-Members' Journals General Subaru Discussions 2015+ STI Discussion