ok first let me give u my mods

injen intake with upper and lower icp

walbro 255

ngk 7s

3 inch turbo back exhaust

ported stock exhaust manifold

megan 02 housing

test pipe

hailman MBC

all on an 05 evo MR

now i have allot of exhaust boltons. so i run a pretty free flowing exhaust but after i put them all together i got huge boost creep. Once the car reaches 5 grand it wont hold boost anymore and will just sky rocket untill fuel cut out. the MBC is set at 20PSI. I was wondering if anyone else has had this problem. I have heard that getting it tuned will take care of the boost creep but that doesnt make much sense to me.

My original feeling is that the megan 02 housing is causing the boost creep. but when i installed it the 02 sensor cross threaded into it. Do you know how much it is for a new 02 sensor so that i can bring it back to the stock 02?

Please let me know what i can do to fix it. my car is undrivable right now.

 

First thing that I would do would be to perform a basic boost leak test. Search results here. I would also double check all of your connections on the UICP and LICP. Good luck!

 

i dont think it would be a boost leak. because im having problems with to much boost. "creep"

 

Wow reading comprehension got the best of me today. Boost creep occurs when the wastegate cannot bypass enough exhaust gas, and routes too much gas to the turbine wheel, which in turns causes it to spin faster which will create higher levels of boost. This is especially true at higher RPM levels. I wouldn't think it's the Megan, since many people have that unit and don't have very many issues. Now what you're experiencing could also be boost spike, which is usually caused by a faulty MBC (shouldn't be the case for you since you've got a tried and true Hallman), a long boost source, and issues with wastegate connections.

As far as the o2 goes, I had the same problem when I installed my exhaust. The darn thing was way over tq'd from the factory. Anyway, I bought a Bosch universal 4 wire from Napa for something like $70, and that did the trick. Better than paying hundreds for a new unit from .

Hope that helped.
-Alex

 

thanks for your help!

What is a 4 wire bosch?

is that an 02 sensor? i thought that it was the 02 housing! because i didnt have the problem untill i installed it. now i think its creep because it only creeps at the upper RPM range like around 6 grand it will shoot up to 24-26PSI and fuel cut out will happen. I have the MBC set at 20psi and it does a good job holding that untill 6 grand.

I wana fix the problem and im willing to put back on my stock 02 housing but i wana make sure that will fix the problem.

Also idk if this helps but when i have my test pipe on the creep is allot worse then when i run my High flow Cat. ive tryd both.

with the test pipe it creeps in 2nd gear.

with high cat it creeps in 3rd gear

 

Hmm still sounds a bit odd. I'd check to make sure everything is fine and dandy with the wastegate. Have you ever adjusted it? The Bosch is an o2 sensor that can replace the stocker.

 

i never adjusted the WGA i took it off when i changed the 02 housing but thats it. and i put it back on without a problem.

If there was something wrong with the WGA wouldnt it creep the whole time? because my car holds 20psi untill like 5Grand then it starts to creep faster and faster.

Has anyone else ever had this problem?

Any help would be great.

AMS said that they have never had this problem on a stock turbo which is what i have.

also if this helps i put on the ported exhaust manifold and the 02 housing on the same day. so maybe the ported manifold has something to do with it.

 

Hmm. Well I mean there is always the possibility that something happened to it when you took it off. It won't necessarily creep the whole time, as the boost will rise to your set boost level as usual, but will creep in correlation with engine load and speed. I'm almost certain it's a wastegate issue. It's obviously exacerbated by the increase in flow due to the free-flowing exhaust, but since tons of people have the same mods and don't have your issue, it would lead me to believe that it's the wastegate.
-Alex

 

i am going to bet that the hole in the o2 housing that merges from the wastegate side to the exhaust side needs to be ported bigger. when i got my megan o2 housing it was about 33mm. after reasearching i went ahead and opened it up before installing it using a dremel to 36.5mm to avoid any boost creep.

you may want to take your downpipe off and measure the hole inside and see if its big enough. if not, dremel it to about 36mm or so. you can do this with the o2 housing,manifold, and turbo still bolted on the car.
https://www.evolutionm.net/forums/sh...+creep+housing

if you measure the o2 housing and its big enough, try cleaning your mbc.

 

test pipe will cost boost creep??

 

The internal wastegate on your stock turbo is designed to bypass exhaust gas flow around the turbine wheel. The 16G has a twinscroll, or divided, turbine housing. At the turbine inlet area each side of the housing has its own separate entrance to the siamesed bypass port at the end of which is located the wastegate flapper valve.

The bypassed exhaust gases exit into the divided chamber O2 housing. You can improve the wastegate bypass flow in one or both of two ways: As someone else already noted, you can either enlarge the merge hole in the O2 housing, or you can port the wastegate bypass port(s) within the turbine housing itself. Sometimes if creep is pronounced then you'll need to do both.

Each and everyone of your exhaust mods(O2 hsg., ported manifold, test pipe, 3" DP, and catback exhaust) have all combined to reduce exhaust backpressure considerably. So, you've increased exhaust flow through the main scroll area and across the blade tips which spins the turbine shaft and the compressor faster. But, in the meantime you've done nothing to improve bypass flow tangentially out through the bypass port.

So, main scroll flow overwhelms bypass port flow capacity. Port the merge hole in the O2 housing and/or port the wastegate bypass port.