If there is sufficient pressure within the turbine housing at 4500 RPM to lift the flapper valve at 12.5 PSI then at higher RPM(5500RPM, 6500 RPM) the pressure exerted against the valve would increase and be considerably higher. If it opens at 4500 RPM and 12.5 PSI, then it´ll stay open when higher internal pressure is acting on it. The problem is not in too tight of a WGA, otherwise it wouldn´t open at 12.5 PSI in the first place.

EDIT: Let´s say for argument´s sake that WG preload is set at 21 PSI. In that scenario there is by definition, no way that the flapper valve is gonna be opening at 12.5 PSI. It wouldn´t be opening before internal pressure within the turbine housing reaches 21 PSI. This seems like pretty basic to me.

Have you ever installed garage door springs? I don´t know how many lbs. they stretch at, but I´ll say that there is no way you´re gonna stretch them before you get to their tested rating.

 

So you think its my 02 wastegate hole? Because for a little over a week, i held 22psi to 7k with no very minor fluctuation, .2 psi. Which leads me to believe its not the 02 housing. Something else is going bad. And i only got 14k on the evo.

 

I think that maybe mrfred might be right. Either by porting the WG "hole" in the turbine housing or doing the porting of the merge hole in the O2 housing you´ll be adressing the same issue. It´s just easier to remove and get at the O2 housing merge hole. If that doesn´t do it then you would have to proceed to the next likely suspect which would be the turbine housing´s WG bypass port("hole").

The O2 housing upgrade will in a lot of cases cause what seems like creep as it reduces backpressure within the turbine housing by a couple PSI which allows the turbine wheel to rev more freely.

It seems wierd but sometimes a too loose WGA with insufficient preload allows the flapper valve to drop and rise where a stiffer WGA will be more stable at higher boost levels. I realize that this seems contrary to logic but I´ve seen it happen on a bunch of my cars.

That´s why I think that it wouldn´t hurt to do an empirical test in your case and compare how two turns looser on the actuator rod compares to two turns shorter. It won´t cost you anything and in the process you´ll be able to eliminate the WGA variable as a possible source of your problem.

 

Thanks for the info.

 

Its the o2 housing. I had no boost creep on my IX in cold weather until i installed the o2 housing. I had the same issue on my 05 Evo and i messed with the preload on the wga and it went away, even at 40 degree weather. I havent messed with it on my IX because its not cold anymore. Ill have to see what it does in the winter and prbl try to adjust it. I even switched the spring on my mbc to a soft one and continued to do it. I ran wg pressure and it was 18psi and creeping.

 

Sorry for bumping an old thread, but I'm having a similar problem to the OP. However, I only have an Apexi'i Power Intake, HKS EVC V Ebc, 3" Perrin Downpipe and Blitz Nur Spec R cat back exhaust.

I experienced boost creep tonight on my car with the ebc turned off (it was 22 deg F outside). In 4th gear at 3k RPM it hit 80kpa (11.6 psi), that's normal... then it creeped up to 131kpa (19 psi) by 6500rpm. The catch is, I have a stock o2 housing. NO TUNE and I just installed a test pipe last night. Last weekend was even colder (16 deg F) and I didn't have any issues but I was running a high flow cat. What can be causing this boost creep issue?

 

interesting thread, subscribed.

So, what you guys are saying it that the o2 housing is the problem???
Or certain o2 housings have design flaws on them????

What about that o2 housing w/ the screamer tube on it?? Will that reduce the chances of boost creep???

Sorry for the bombardment of questions I'm ready to put on my helix o2 housing and then i'm getting a tune by kunal done.

 

Funny thing is, I have the stock O2 housing on my car. I'm still have MAJOR boost creep...

 

The significantly colder weather coupled with the switch to the less restrictive test pipe are causing your creep issue.

 

That's what I initially thought... However, what will solve this issue?

 

i had same prob with the megan o2 last week ...boost spike to 26 psi....enlarge waste gate merge whole as much as u can ....till u start to hit the welds ...

 

I have a stock O2 housing, the only other thing I can think of is putting the hfc back on. I don't wnt to as it was very restrictive.

 

My buddy just finished installing his Helix o2 housing and he gets major boost creep around 4.5-5k he is hitting 24-25psi. He is not tuned and just has basic bolt ons. He is running on stock boost.

 

Does the opening of the wastegate dump on the hot side itself have to be ported to allow more air to flow out of the wastegate itself? Do people experience this issue with an O2 housing that dumps instead of recircs?

 

I think I might have found something that might be the cause of this boost creep issue. First off, how many people that are experiencing this issue have a stock Evo IX Turbo?

I ask because the stock IX turbo has a single flapper on the 10.5 hotside vs. the Evo VIII 10.5 hotside which has a dual flapper to let more air out of the wastegate dump section. This could be the problem for the boost creep which feels similar to the wastegate being stuck in a semi-open position instead of fully open to left the air out. Does anyone have a better solution or explanation for this occurrence?