Turbo Boost Creep Creeping T25 14B 16G [Merged]

[tstkl]

basically, with a high flowing exhaust, the exhaust gases see lest resistance through the turbine wheel than through the wastegate, so the boost creeps to a higher level because the turbine wheel spins faster due to more exhaust gases. The sharp 90 degree angle the wastegate makes with the turbine housing is usually to blame for this. Porting the o2 housing and making the wastegate tract a less restrictive path will cure boost creep (insert some old man here), and it isn't really a bad thing as long as you aren't boosting past the limits of your set up. That could mean your boosting more air in than your fuel system can support, or in my case, your knocking due to high boost/high intake air temps.

but a search probably would have told you all this.

 

[UMR98GSX]

I never creeped when I still had my T-25 and a 3". I also had a 3" O2 housing though.

 

[slipstream808]

Yeah... creep with a T-25 . That is something not to be worried about. Boost will fall off too fast on that teeny turbo. Just make sure that the T-28 you get has a good enough wastegate to flow out all of the exhaust gasses.

 

[toomey200]

got my stock 7 bolt with my evo3 b16g and xs power fmic with full 3 inch exhaust. i turned my boost to around 10 and when i get to my redline my boost is at about 16 or 17psi. is this because i have no internals done and it spool the turbo fast enough?

 

[mjarrell20]

Port your 16g and it will eliminate the boost creep. Try a search, I saw this same topic on the boards just the other day with many post in it.

 

[jumpfroggy]

Boost creep doesnt have much to do with internals. It happens when your exhaust can flow easier than the wastegate can handle. Usually once you hit boost (10psi) the wastegate opens and lets any extra exhast bypass the turbo, otherwise you'd get more and more boost (creep). When you have a bigger exhaust it lets more exhaust flow, which makes this worse. You need to check out your wastegate (cont)

 

[jumpfroggy]

You mentioned that you turned your boost to 10. You have a boost controller? Possibly it's hooked up incorrectly. Maybe there'd a leak in the vacuum hose to the wastegate. When did this start? Did you just install anything?

If its not a leak or something, you could port the turbo, or get an external wastegate. I dont think youre at that level yet though. Post more info, what's the history?

 

[toomey200]

i put the turbo on over the weekend and connected the BC the other night. it is hooked up properly i looked online how-to do it so... i guess ill just get an external waste gate... is there any other cheaper options for me to do at this point?

 

[mjarrell20]

This O2 dump could help. But like "jumpfroggy" said it does sound like the boost controller was improperly installed, double check over it, mistakes happen.

 

[chuckg]

i guess ill just get an external waste gate... is there any other cheaper options for me to do at this point?

I wouldn't go external yet. There's really no reason to spend all that money right now when you could easily fix the problem by porting your turbo or having a machine shop do it. My .02.

 

[nightspeed87]

Why not just cut open the exhaust tube yourself and make your own dump tube? Does anyone do that? Ive heard dumped tubes on dsm sound really loud and aggrivating ( at least to other ppl ) Is this true? Does it drown out the sound of the bov or how does that work.?

 

[mjarrell20]

It's only loud when you're at wot and the waste-gate is fully opened and yes it drowns out everything. Yes to some it is aggravating but others find it to be a nice aggressive sound. But just rolling around town it's not to noticeable.

 

[zippyshoe]

After porting your turbo, you will also want to port your O2 sensor housing as well, focusing on the wastegate passage of both your turbo and the O2 sensor housing. Also, something quick you might want to check is to make sure that nothing is blocking the movement of the wastegate arm (such as the lower exhaust heat shield, etc.) Good luck resolving your boost creep problem!

 

[kenamond]

This is a common problem. The evo3+larger exhaust tends to creep. I've posted too many times about this, but I'm a glutton for punishment .

First off, the WGA doesn't open the flapper enough to sufficiently bypass the turbine at low boost. If the door ain't open enough, too much exhaust goes through the turbine and generates more boost than you're wanting.

Second, anything you do downstream of the stock WG flapper won't help other than possibly cutting out the divider in the turbine housing that separates the WG and turbine exit passages, but a search should convince you that this isn't a good idea.

If it is actually creep, you have 3 worthwhile options:

1) Port the turbine housing PROPERLY along with the O2 housing.
2) Run an external WG or an internal that doesn't use the stock flapper (the flapper is removed and a much higher flowing, external-WG-style valve disposes of the exhaust from within a special O2 housing).
3) Run 20+psi boost if you're going that way anyway. The stock WG setup tends to "catch up" to the turbine flow by 20psi, so creep is less of a problem. This is cheapest in the long run if your aim is 20+psi, but if you're not ready to go there yet, options #1 or #2 should be considered.

I've been pushing for someone with sufficient motivation to find a WGA that has greater throw and is otherwise compatible to replace the evo3 WGA. It just doesn't rotate the flapper enough to open the passage enough. IMO, that's the true flaw in the evo3 b16g on a DSM.

 

[grnchevyz]

Went from stock turbo to EVO3 with FMIC, FIC 550's and Walbro 190lph. Already had HKS HiPower 3" Exhaust on.

My problem:

WOT gives an immediate 20+PSI with no lowering or settling down. I thought boost creep settled after a while?

On slow boost, I can see it and feel it creep. I have not yet checked the WGA arm I will do that tomorrow.

If it is indeed boost creep...I guess my only option would be to port out the turbo and O2 housing correct?

Thanks again guys.

 

[diablos991]

Be sure that your EBC is hooked up correctly.

 

[grnchevyz]

Even without any controller be it the factory one or my profec, I still get 25+ on WOT.

I should see about 11psi with no controller attached no?

 

[diablos991]

I had my greddy profec b-spec 2 hooked up wrong on my t25 and I hit 24 psi.

My issue was that I needed to have the solenoid connected directly to the wastegate with nothing spliced into it. (I originally had my TypeS spliced here)

Afer I fixed that, it worked like a champ.

 

[cs82685]

Have you looked at anything yet. The first two things I would check are the WGA arm and the Vac line from the compressor housing to the WG, maybe it's leaking.

 

[Boosted98gsx]

take a vacuum line and run it from your boost source to the wastegate actuator nipple. You shouldn't boost more than like 10-12

 

[oldman]

WOT gives an immediate 20+PSI with no lowering or settling down. I thought boost creep settled after a while?

Uncontrollable boost = boost shoot straight up and no return.
Boost spike = spikes then settle.
Boost creep = initially hitting boost setting then slowly creeps up as rpm increases.

Even without any controller be it the factory one or my profec, I still get 25+ on WOT.

If a hose was connecting the pressure source to the wastegate, sounds like you have boost creep.

 

[grnchevyz]

I thought that by NOT connecting any vaccuum lines to the wategate I would see only the boost that the turbo is set to...i.e.: 10-12psi.

Was I not right?

I'll try hooking it up to the intake manifold and see what happens.

 

[NewB2dsm]

I thought that by NOT connecting any vaccuum lines to the wategate I would see only the boost that the turbo is set to...i.e.: 10-12psi.

Was I not right?

I'll try hooking it up to the intake manifold and see what happens.

yes you are wrong, hooking up no pressure source will cause the boost to go as high as it possibly can. Hook it straight to manifold pressure and you should see 11-12psi. If it does this and holds then someone is wrong with your boost controller. If it slowly creeps upward and never stabalizes really then you have boost creep.

 

[Ultimatedsm]

Connect your wastgate vacuum hose to a ported vacuum source (Nipple on J pipe or intercooler pipe or turbo itself). By not connecting the wastegate vacuum hose will build unlimited boost.

 

[Ultimatedsm]

Don't hook it to your manifold pressure, NEVER t-off anything to your BOV line or manifold pressure source. Wastegate vacuum hose to a ported or pressure vacuum source only.