BluEVOIX

iTrader: (69)

Sorry for some reason I kept missing that your on a stock o2 housing. I was sleepy as hell so when I was reading over your first post that night for some reason my brain registered the "upgrade their o2 housing, mine is stock" into yours being the upgraded o2 housing.

So what ever I've been arguing about will not apply to you. My appologies.


In that case. You've mentioned that you already are using the nipple off the turbo J pipe for boost source. Just want to make it clear that you have completely removed the the vacuum line to the stock solenoid? So the bc vacuum line is as follows; (Turbo-------->MBC--------->Wastegate) And the stock solenoid is completely out of the picture?

Next thing I suggest you check is to make sure that those vacuum lines dont have any cracks or rips. I know that the stock vacuum lines develope cracks that leak over time. If your running aftermarket vacuum lines just double check those as well.

Another thing check is you have connected the boost controller with the bottom nipple as the turbo boost source and the side nipple to the wastegate?

berns

iTrader: (12)

Everything is hooked up right and I have no leaks. It's got to be the wastegate or the mbc. My friend has a spare hallman that I'll be going to pick up in a bit, I'll put it in and go from there.

OneEyedJack

iTrader: (6)

My .02, almost undoubtedly the MBC as well. I have nearly the EXACT same setup as you.

I have Perrin intake, Perrin 3" TBE (with high flow cat) and Hallman MBC. Stock O2 housing, just like you. Alos tuned to 21 psi. Sometimes I see spikes to 23ish in low RPM but it tapers nicely to 18psi by redline every time in all gears (slight variations but same safe trend.) I even live in Hartford and have a 2006 so we have same climate and motor.

ONLY DIFFERENCE: My MBC source is the turbine, not the manifold.

I sincerely believe this is your MBC. Sorry I do not have an extra one to ship you.

Cheers,

Jack

berns

iTrader: (12)

Thanks. Big difference is the cat though, but still, I agree with you. My MBC was hooked to the turbo until yesterday, the only reason I switched it was to narrow down the cause.

We'll know today if it's the mbc, I hope it is.

berns

iTrader: (12)

Well, I put in a new boost controller and..... still the same ****.

Next up is the wastegate, I'll see if I can work on it during the week. this is annoying as ****

turbo addict

iTrader: (2)

buy an aftermarket O2 housing with an external dump wastegate tube. this will fix your problems. When the wastegate dumps to the atmosphere there is no backpressure compared to that is in the rest of the exhaust. it controls boost much better aned makes more power. I have one of these.

Also boost spike is too much pressure down low and tapering up top. and creep is when it starts off were you want it and then over boosts as you rev to readline.

berns

iTrader: (12)

i'm not going to drive around with some loud dump on my 350whp car. Shouldn't have to make the car unreasonably loud to fix a problem.
Thanks for the clarification on terms though, boost spike usually hits there, and then tapers. My car acts like boost creep, but starts to taper way up top.
Anyway, it's irrelevant. The problem still exists, and I drove 2 other Evo's recently that don't act like my car at all.

Virgil072

I'm assuming this is happening to those that are tuning thier car's via the stock turbo and is resulting from either an upgraded 02 housing or pushing more boost through an 02 housing that has a wastegate that isnt designed for it? What will the stock waste gate diameter safely hold w/o sustaining boost creep?

detroit pistins

iTrader: (102)

awsome discussion guys!
Berns, so did u figure out what the issue was?


i am having the same issue, however, i do have an after market external dump tube but without a tune yet. here are my mods:

perrin intake, perrin dp + br catless back ex. ppi ported ex manni, map o2 housing, hallman mbc.
I will swapp out the mbc and report back.

berns

iTrader: (12)

never fixed the issue, however i realize most evo's have it. i did take my intake out and put the stock box back in, i like the way the car drives much more now and the boost spike isn't as bad or hard to control. car still spins all 4 tires in the cold so i don't feel a huge loss in power.

detroit pistins

iTrader: (102)

did u try swapping the wga?

berns

iTrader: (12)

nope. i have a feeling that's got to be the problem though. i'm too lazy and it's cold and rainy out and i don't want to buy a new wga. i feel like the install, while not difficult, will be somewhat of a *****. i'm much more motivated in the summer.

detroit pistins

iTrader: (102)

dont blaim ya man! but i think iam doing that tonight, so i will report back and let u know how it goes. gl!

berns

iTrader: (12)

yes, please do. i just read a bit and someone said with a swivel ratchet, it's pretty easy to take the wga out from undernear the car without removing anything.

Hiboost

iTrader: (9)

Some food for thought:

I've seen creep induced like this when you have a WGA cranked down with too much preload. Basically your base boost would be higher that way but the amount of travel restricts how much flow can get out that passage. The typical opening angle of the WG flapper is also restricting quite a bit of flow if you compare it to just an opening with no flapper. You did mention you turned down the boost to ~15 psi and that it only creeped a few psi which means that something is wacked with either the WGA or boost control setup you have. I would verify you have a full (and strong) boost signal reaching the MBC and that you don't have restrictors limiting the flow of pressure to the MBC, which may be too weak to move the WGA open. Also make sure the MBC is flowing the correct direction as all kinds of issues can occur if hooked up backwards! I'm not sure if you have a small bleed hole in the line after the MBC but before the WGA, but make sure it's not TOO big as that will weaken the signal and let the WG shut again with no control.

To find the minimum boost level that your physical WG passage & O2 housing can flow you could just run a boost source directly to the WGA and test at what RPM you start creeping and what the max psi reached was. Use a fresh line with no holes or restrictors in it so that the test is a valid snapshot of what your minimum boost actually is. Likely you will hit ~13-15 psi at lower RPM's but at some point it will creep in the mid to upper RPM's. If that ends up being 20 psi then you should be able to set boost for 20-25 psi with 1-2 psi spike at most and have it hold steady until you reach the flow limits of the turbo and then taper at higher RPM's.

Increasing the flow through the bypass side of the O2 housing may help but your description of having boost rocket up to 20 psi and then creep up to 25+ slowly is a warning sign that the signal to the WGA is the issue, or possibly the WGA itself. I've used the Forge WGA with a full signal line and MBC and had excellent boost control results on my Evo X, just make sure the bleed hole is just big enough to relieve pressure buildup in the line. The higher you are trying to raise it above the WGA's natural opening pressure the larger the hole, just start smaller and slowly increase. Going too small (or no bleed hole) will actually keep your WGA open with trapped boost pressure between shifts and you will feel the lack of spool.

Now I use an ATP O2 DP that has a Tial 44mm WG so my boost control is even more stable, but I mainly went that route because my internal WG failed due to a design issue with the Evo X GT30 turbos.

Hope that helps!