Boost creep / fuel cut

**Blinden** · 08-28-2006 02:31 PM

I've been looking at doing a UTEC/TBE on my car, and the closest local shop, which seems pretty reputable, has given me the following information, the bottom is my original email. I know I'm a good bit noobish when it comes to this, but, it is what it is. I used the information in this thread to educate myself and tried to gather more infomration off of this fellow. He seems to go against what was originally said in this thread, and I'm just confused. Also, does that seem reasonable for labor costs? I don't have a second car to use to do this by myself right now.

Brandon,

Boost Creep will happen almost always with a 3" DP. I would definately
take off
the stock cat, and run a cobb AP to fix the problem. You are looking
at about 300$ in labor to install the whole system.

Chris

Quoting Brandon Linden <brandon.linden@gmail.com>:

> I thought that the boost creep was only an issue if the turboback was
> catless, I thought as long as you used a high flow cat the car would run
> without the boost creep issue. A major concern of mine is that the stock
> cat is doing a lot of restricting and losing some HP. Thanks for the
> extremely fast reply, do you guys run a shop as well? I assumed you did
> because I saw dyno time on the website. I'm in westmoreland county and as
> trivial is it may seem, I would rather let someone else do the work instead
> of miss or mess anything up on my own, at least while this is my only car.
>
> On 8/28/06, sales@slowboyracing.com <sales@slowboyracing.com> wrote:
>>
>> Brandon,
>>
>> As far as the exhausts go, I recommend the invidia. The Tip on the
>> invidia is a
>> titanium tip, and looks pretty badass. When you do your full exhaust,
>> you'll
>> want to do the access port at the same time. With a turbo back exhaust,
>> the
>> subaru tends to boost creep, causing the car to run very crappy. This is
>> very
>> easily corrected with one of the stock maps in the access port.
>>
>> The only differences between those exhausts are the material in the tip.
>>
>>
>> Chris
>>
>>
>>
>> Quoting Brandon Linden <brandon.linden@gmail.com>:
>>
>> > I'm interested in getting a new exhaust put on as well as adding a cobb
>> AP
>> > in the next few weeks, and I have a few questions. First, as far as the
>> > TurboXS systems go, whats the differences between the RFL-TI and the
>> > "Standard" and and how much would it be to have an exhaust installed and
>> how
>> > long would it take?
>> >

**sstricker** · 08-28-2006 04:25 PM

just got my 05 STi on saturday. im experiencing what i believe to be boost creep. my mods are..... perrin lightweight pulley, perrin 816cc injectors, walbro 255, turboxs type H bov, AEM CAI. would a tial 38mm wastegate cure this?

i guess what's happening is under hard acceleration... boost creep/fuel cut? check engine light comes on and cruise light flashes?! what is the easiest mod to cure this? i understand that the Cobb AP will? cure this or not?

thanks guys,

scott

**bkzshabbaz** · 08-28-2006 06:05 PM

If you read the entire thread, the two options are to get a high flow cat to put alil restriction back into your exhaust system, or port your internal wastegate. Engine management wont solve boost creep, it will just mask it, correct me if im wrong.

**YBNormal07** · 08-28-2006 07:34 PM

Originally Posted by Blinden

I've been looking at doing a UTEC/TBE on my car, and the closest local shop, which seems pretty reputable, has given me the following information, the bottom is my original email. I know I'm a good bit noobish when it comes to this, but, it is what it is. I used the information in this thread to educate myself and tried to gather more infomration off of this fellow. He seems to go against what was originally said in this thread, and I'm just confused. Also, does that seem reasonable for labor costs? I don't have a second car to use to do this by myself right now.

Brandon,

Boost Creep will happen almost always with a 3" DP. I would definately
take off
the stock cat, and run a cobb AP to fix the problem. You are looking
at about 300$ in labor to install the whole system.

Chris

Quoting Brandon Linden <brandon.linden@gmail.com>:

> I thought that the boost creep was only an issue if the turboback was
> catless, I thought as long as you used a high flow cat the car would run
> without the boost creep issue. A major concern of mine is that the stock
> cat is doing a lot of restricting and losing some HP. Thanks for the
> extremely fast reply, do you guys run a shop as well? I assumed you did
> because I saw dyno time on the website. I'm in westmoreland county and as
> trivial is it may seem, I would rather let someone else do the work instead
> of miss or mess anything up on my own, at least while this is my only car.
>
> On 8/28/06, sales@slowboyracing.com <sales@slowboyracing.com> wrote:
>>
>> Brandon,
>>
>> As far as the exhausts go, I recommend the invidia. The Tip on the
>> invidia is a
>> titanium tip, and looks pretty badass. When you do your full exhaust,
>> you'll
>> want to do the access port at the same time. With a turbo back exhaust,
>> the
>> subaru tends to boost creep, causing the car to run very crappy. This is
>> very
>> easily corrected with one of the stock maps in the access port.
>>
>> The only differences between those exhausts are the material in the tip.
>>
>>
>> Chris
>>
>>
>>
>> Quoting Brandon Linden <brandon.linden@gmail.com>:
>>
>> > I'm interested in getting a new exhaust put on as well as adding a cobb
>> AP
>> > in the next few weeks, and I have a few questions. First, as far as the
>> > TurboXS systems go, whats the differences between the RFL-TI and the
>> > "Standard" and and how much would it be to have an exhaust installed and
>> how
>> > long would it take?
>> >

A TBE with HF cat offers enough back pressure to prevent boost creep.

The Cobb is stated to resolve boost creep, and according to some folks, it does work. I do not have personal experience with this however. Plus, the laws of physics can't be changed, and I believe the application Cobb uses to remove boost creep actually delays/masks it. By all logic, if the mapp is preventing creep, that means it is limiting boost somehow, and to me this speaks to a lower HP output. Just my thoughts though. You should speak to Cobb directly for questions on how they control creep on a 2.5 with VF39.

**Blinden** · 08-29-2006 02:20 PM

Man, I didn't think this would get very confusing, but 3 different sources have said 3 different things now.

what about a stealthback, no issues with boostcreep on a stealthback? is it even worth it though, what kind of performance can I expect? okay, imma go back to the clubwrx.net search function again.

**BlackSTI2006** · 08-29-2006 04:20 PM

Option 3 was to find an external wastegate....my question is from everyones experience which one would work best if i was running a catless downpipe into an apexi gt-spec catback with a resonator, anyone want to point me in the direction of where they got their external wastegate and which one worked the best for them?

second question....on average what are people paying to have the wastegate ported?

Thanks~chris

**Never_Summer** · 08-29-2006 04:36 PM

deadbolt will port and polish your turbo for like 180 or something i think. An ewg will definitely prevent boost creep but aside from the like 500 bucks you spend on it, you will also have to get it tuned. Also a ewg is overkill on such a small turbo as a vf-39.
Cobb adjusts the wastegate duty cycle to try and overcome boost creep

**BlackSTI2006** · 08-29-2006 04:40 PM

Originally Posted by Never_Summer

Cobb adjusts the wastegate duty cycle to try and overcome boost creep

so your saying cobb can fix it or their AP can? because on here everyones making it seem like the AP will just bypass the issue, i would think they adjusted for the issue for stage 2 people by controlling the stock EBC since its made to be used with a TBE.

Thanks~chris

**testes1010** · 08-29-2006 06:18 PM

Originally Posted by BlackSTI2006

so your saying cobb can fix it or their AP can?

the AP masks the issue, you may not have boost creep but your will not be optimally tuned. A ported wastegate will allow for a more aggressive tune capable of much much more power.

**BlackSTI2006** · 08-29-2006 09:18 PM

Originally Posted by testes1010

the AP masks the issue, you may not have boost creep but your will not be optimally tuned. A ported wastegate will allow for a more aggressive tune capable of much much more power.

so your saying cobb knows this is an issue with the system but they dont mention it and they cover it up by masking the cel? one person says they adjust the wastegates cycle while you say it just masks the CEL...im curious to which is the accurate answer here there is arguments to both sides anyone else wanna chime in? im not doubting either story just trying to clear this up for myself and others because theres all different stories being thrown around here...

**testes1010** · 08-30-2006 06:05 AM

Originally Posted by BlackSTI2006

one person says they adjust the wastegates cycle while you say it just masks the CEL...

it masks the problem not the CEL, in the form of a much less aggressive tune by altering wastegate duty cycles...

**StupidMan** · 08-30-2006 07:08 AM

Anything, besides porting the wastegate or putting on an EWG, masks the problem, either by reducing flow of the exhaust system or changing the wastegate duty cycle.

The problem= Small wastegate opening
The result= Boost Creep/spike/CEL/fuel cut
The fix=Larger wastegate opening

its not that complicated