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Old 07-29-2012, 05:38 AM   #401
jebjkey
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Boost creep is purely mechanical, so only mechanical changes will affect its severity. That can be individually or any combination of: the intake, the turbo, the WG, and the exhaust. Each one will have an effect on boost creep; making it better, making it worse, removing it entirely, or giving you boost creep when you did not have it before.

Porting the IWG may be enough to fix the problem or it may just lessen the severity of your boost creep. For me, porting the IWG lessened the severity when I had an aftermarket intake on the car.

Components like exhaust and intake will have an effect also. The DP being catted or not, the design of the DP, etc. I put a stock intake back on my car, and along with the ported IWG, my boost creep was fixed.

A 3 port EBCS will have zero effect on boost creep. Put any EBCS at 0% WDC and you effectively connect the turbo outlet directly to the WG actuator and there is nothing else any EBCS can do.
When your EBCS is at 0% and boost is not at WG spring pressure (~9#) then you have boost creep (or a leak in your boost control system). A 3 port should allow you to have better control over boost due to the fact that it is an interrupt system vice a bleed system, but it cannot fix boost creep. A 3 port EBCS will require a tune to set up your map correctly to control boost.

An EWG will fix boost creep because the WG port size (38mm or 44mm generally) is larger and therefore it can flow more exhaust to bypass the turbine - removing the cause of boost creep. An EWG will require a tune to set up your map correctly to control boost.

If you have boost creep, it will be worse in higher gears and it will be the worst from ~4800-5500 RPM in all gears. Take a look at the thread I have on boost creep , link. I should probably update the thread with my current setup though. I need a good data log so I can post a graph. I use a hybrid boost control system with a 3 port EBCS and a Hallman MBC in parallel. I like it.
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Old 09-11-2012, 06:59 PM   #402
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if i go stage two with a invidia catless dp and SF intake and use the lwg map on cobb tuner i shouldnt have boost creep right?
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Old 09-11-2012, 10:17 PM   #403
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Quote:
Originally Posted by S1CkWrx View Post
if i go stage two with a invidia catless dp and SF intake and use the lwg map on cobb tuner i shouldnt have boost creep right?
You probably will have boost creep.
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Old 09-11-2012, 10:26 PM   #404
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even on low waste gate map?
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Old 09-12-2012, 04:30 PM   #405
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Originally Posted by S1CkWrx View Post
even on low waste gate map?
It's common for those exact mods to cause boost creep in higher gears on the 09+ cars. Essentially the wastegate cant bleed enough boost even at 0% WGDC in 4th and 5th gear to keep from boosting higher than target. I ran into this first hand on my 2010 WRX.

I would recommend going stage 2 with catless DP but keeping the STOCK intake. Along with your stock catback exhaust boost creep should not be a problem.

I did not take the normal path to solve boost creep. While people say it is a mechanical problem, it sorta is and sorta is not. Strictly technically speaking it is a mechanical issue that cannot be tuned out. But if you change parts on the car you can actually control it or make it so that you are not even creeping due to higher boost targets and that the turbo has to work harder. I got a big ass intercooler, an EBCS, and cranked up my target boost to 21psi. Now I have zero boost creep issues and my WGDC's are in the 60% range in 5th gear WOT. I peak at 21 psi and level off at 16psi at redline. While some will argue this is not how you solve boost creep I disagree 100% due to experience. With the mods and tune I have, the wastegate is never trying to bleed off more boost than it can handle, therefore I never have boost creep or 0% WGDC's.

mods:
FMIC
Invidia catless turbo back
Turbo XS intake
Grimmspeed EBCS
Wideband 02 (always necessary)
Cobb Access Tuner Race( I tune my own cars)

Car puts down 313hp/354tq at the wheels. AFR target 10.8:1.
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Old 09-12-2012, 04:57 PM   #406
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i dont have boost creep with an AEM intake, catless invidia turboback, pw top mount, gfb hybrid bov and gs ebcs.

i havent been thru the winter months while stage 2 yet though...
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Old 09-12-2012, 06:01 PM   #407
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well i just bought the cobb sf intake, and been using the invidia n1 race catback im not gunna return them lol... il just see how it is i guess when i put it all on and baby it
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Old 09-13-2012, 05:54 AM   #408
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Hi,

Sorry I am new to this but I recently installed a decat downpipe and decat center piece. Ever since this was done I am only boosting to 0.6bars instead of the usual 1.1bars on my GC8. I have a Blitz NUR Spec back box so its not full decat.

Would this really result into boost creep? Its MY99 Type RA V-Limited.
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Old 09-13-2012, 06:37 AM   #409
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Your problem has nothing to do with boost creep.
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Old 09-13-2012, 10:25 AM   #410
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Quote:
Originally Posted by Dreamz Unlimited View Post
Hi,

Sorry I am new to this but I recently installed a decat downpipe and decat center piece. Ever since this was done I am only boosting to 0.6bars instead of the usual 1.1bars on my GC8. I have a Blitz NUR Spec back box so its not full decat.

Would this really result into boost creep? Its MY99 Type RA V-Limited.
Did you get tuned for your mods?
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Old 12-11-2012, 06:48 PM   #411
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Default creep

I recently purchased a 2011 STI with Q300 TBE catless dp, Cobb SF, AP stage II+ 93 octane map, otherwise stock motor. First of all I can hear the wastegate (I think its the wastegate) wheeze...I assume that it is releasing pressure into the exhaust. Is that a sign of boost creep or just normal? I can reinstall the oem airbox if thats all I need to do to minimze or eliminate boost creep. I havent seen any CELs but not sure whether boost creep would do that.

Never used the AP and was wondering whether I can check for boost creep with it?

Welcome any feedback to ensure that I have a safe setup.
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Old 12-11-2012, 07:25 PM   #412
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Wastegate flutter is normal. It just sounds louder because of your intake. A way to check for boost creep is to keep an eye on your boost levels during WOT pulls to redline. You can monitor your boost levels through your AP. Do a couple of data logs in fourth gear, that'll give you a good idea. If your boost jets up past specifications through multiple runs, you may have boost creep.
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Old 12-11-2012, 09:37 PM   #413
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Default creep

Thx. I'll take a set of readings. Based on what I've read in this thread, it sounds like going back to the oem airbox might be the best way to safe guard against creep given that I have the Q300 TBE catless already installed.
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Old 12-11-2012, 10:25 PM   #414
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i wouldnt worry too much about it. ive got the same exhaust along with an even colder air intake (AEM) and have no creep. just take some logs and verify you have no creep and then enjoy the car
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Old 12-11-2012, 11:34 PM   #415
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Quote:
Originally Posted by Asharus
i wouldnt worry too much about it. ive got the same exhaust along with an even colder air intake (AEM) and have no creep. just take some logs and verify you have no creep and then enjoy the car
Lol 'colder' air intake..
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Old 12-12-2012, 10:37 AM   #416
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Quote:
Originally Posted by jaboyd View Post
Thx. I'll take a set of readings. Based on what I've read in this thread, it sounds like going back to the oem airbox might be the best way to safe guard against creep given that I have the Q300 TBE catless already installed.

Log your waste gate duty cycles, boost target, actual boost, and the Turbo Dynamics tables doing a 3rd and 4th gear pull. If your actual boost is higher than your boost target and your WGDC's are 0%(the ECU can't bleed off any more boost) then you have boost creep.
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Old 01-19-2013, 05:01 PM   #417
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I'm sure this has been asked a million times, but is this as common on a regular wrx? I have a 2005 wrx, flashed stage one with the Cobb. And I was considering a catless tbe. But I never thought to look for this and didn't notice this because I rarely push the turbo that hard. I suppose I could use the Cobb to data log it but I'm such a noob, I have no clue.
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Old 01-20-2013, 08:03 AM   #418
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Hmmmmm Interesting
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Old 01-21-2013, 11:33 AM   #419
jebjkey
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If you want to see where you are starting from then do this test:
1. Connect the turbo outlet nipple directly to the waste gate nipple (alternatively you can set your WDC to 0 across the board in ATR).
2. Datalog a pull to redline
3. Look at what boost does across the RPM range (e.g. does it hold steady at ~9#, does it steadily rise as RPM goes up, does it suddenly go up significantly, etc.)

If you have no signs of Boost creep, then your boost should stay pretty steady at WG pressure (~9# give or take). Depending on the results of the above test, you can see how close you are to having boost creep problems and go from there.

Here is what mine looked like when I did the test above:


If you cannot read the legend the upper two lines are with an aftermarket intake and the lower two are with the stock air box, both have a 5th and 4th gear run.
Here is my setup:
Stock air box or Aftermarket intake as appropriate
Silicon turbo inlet
VF-39 with ported WG
Stock intercooler
Stock headers and UP
Catted bellmouth DP
3" CatBack
AP (using ATR)
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Old 01-22-2013, 03:09 PM   #420
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Nice graph jeb...ive always said aftermarket intakes have a significant affect on overboost/boost creep.

Last edited by Tripintaz; 01-22-2013 at 03:17 PM.
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Old 01-22-2013, 03:38 PM   #421
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Default boost creep

I went back to OEM air box from SF (with metal box) coupled to my Q300 catless dp (2011 STI) and the creep is gone! Simple fix...yea!

My peak boost was hitting 21.7 with SF, now running 19.7 - 20.0 with the changeover and retune...simple and effective!
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Old 01-22-2013, 04:32 PM   #422
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Cool thanks. Yeah I was gonna say would an intake or something have an effect on anything?
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Old 02-01-2013, 09:49 PM   #423
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Thanks for the wealth of info! I've been hearing so much about boost creep but thankfully it doesn't seem like it'll much of an issue for me as I plan on keeping the stock catback.
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Old 02-02-2013, 03:07 PM   #424
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What if you WANT boost creep? STX requires no changing boost levels. Creep will help on stock boost tables
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Old 02-02-2013, 03:43 PM   #425
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Quote:
Originally Posted by my name is joe View Post
What if you WANT boost creep? STX requires no changing boost levels. Creep will help on stock boost tables
Boost creep is NEVER good... It won't help you go faster, it'll help you make your engine go boom...
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