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

[Mr Peepers]

I know you just put the turbo back on, and I'm sure you don't want to remove it again, but here's an "easy" way as long as you replaced the mani to turbo stud with another bolt. It's still possible to do as long as you can pull the stud out with the turbo still attached.

-Try to get the 4 mani to turbo bolts loose. If you can't, drive the car around a bit and try again. Heat and PB blaster/liquid wrench help.
-Unbolt your downpipe. Again, heat and rust penetrant if they won't budge.
-Unhook the battery.
-Take out the oil dipstick mount(it's easy to blow the alternator fuse trying to get the bolt out with the battery hooked up). Don't worry, no oil will come out.
-Take the WGA arm off from the flapper lever or take the WGA off completely.
-Undo the clamp on the center section of the turbo. It's a single bolt holding it together.
-Unplug the o2 sensor from the harness.
-Remove the 4 turbo bolts the rest of the way.
-Carefully pry the turbine housing from the rest of the turbo, making sure it comes off evenly without bending any turbine blades.
-Work the turbine housing underneath the car and pull it out. The o2 housing/o2 sensor will come with it.
-Unbolt the o2 housing from the turbine housing.

Now you can begin to port for boost creep.
I recommend a die grinder(electric or pneumatic) and double cut carbide burrs. The "flame" shape is the most versatile IMO.
Work slowly and continually check your progress.

Here are some articles/threads:
http://www.dsmtuners.com/forums/art...oler/186525-how-cure-boost-creep-porting.html
http://www.dsmtuners.com/forums/bolt-tech/217409-porting-my-14b-oldman-your-needed.html
http://www.dsmtuners.com/forums/turbo-system-tech/275021-oldman-could-you-grade-my-porting.html

You want to guide the exhaust gases into the WG hole. You unshroud it by grinding material directly above the entrance to the hole and radius the top of the entrance. Leave the bottom of the hole alone since it "catches" some of the exhaust gas. You can also port the WG hole to better match the flapper, but be careful not to go to far and compromise the seal when it closes. Otherwise you'll have to deal with slow spool up from gases leaking past, and possible erosion. The overlap should be about the thickness of a nickel.

There are many more techniques scattered across these forums.

 

[TeeWX98GST]

Well, I just got done doing a boost leak test with a tester I made myself (20psi Test), And I found 3 leaks, an Intercooler Pipe Coupler, my BISS, and a vacuum line off the TB. I fixed all three of the leaks and put the car back together and it has stopped studdering at WOT and it runs amazing, I also seem to have lost my idle surge .

However, I was wondering, what exactly is going on? I don't have a logger yet but I am going to be getting one here soon. At WOT on 15psi (what I normally run) she pulls good and very hard until about 5.5-6krpm then I notice on my boost gauge (autometer), it will start to "creep" if you will back from 15psi down to like 12 slowly until I shift. I'm shifting around 6.5-7k. I still get a TINY bit of studdering when on the way to WOT, I'm guessing this is just turbo lag? and I get a little bit when it starts to creep on me, like barely noticeable but still studdering. Should I be shifting lower? Is this kind of boost creep normal? Do I have a small leak or something I missed..? Thanks for the help guys.

 

[thorlief4g63]

Turbo lag reffers to the delay when you hit WOT and the turbo needs to spool still. That happens at low rpms like if you stomp it at 1500 not 6000.

 

[TjPhillips36]

I believe the stock turbo is just simply too small and unable to keep up the airflow at those RPM's.

 

[JayRolla]

Ohh the joy of a t25 turbo. They really cant hold boost at all at high rpms. Creep is when you hit 15psi then slowly boost will rise. You just have a crappy turbo,

 

[TSi_with_psi]

I agree with what has been said. The T25 is simply to small to hold boost to redline. You should consider upgrading to a 14b or 16g. That would fix your problem of not being able to hold boost to redline, and would give you a bit more HP.

 

[qiklitltsi]

Its the t25 just get a good 14b and 2g install kit for it and you should be good, itll cost around $300 if you get a used 14b.

 

[kenamond]

As everyone has already said, this isn't creep. Rather, it's the small T25 hotside choking on all that exhaust at high rpm. It just can't flow enough on the top end.

As for the stutter, I'd check your plugs and gap. Use NGK BPR6ES gapped to 0.028" (ignore the NAPA guy if he tries to sell you something else). They're $2/ea. Get a logger if it's in your budget. Running above-stock boost without one is a risk, and it can tell you if you have other problems. It might be that you're running out of fuel on the top end, knocking, etc., neither of which are good for your motor.

If you plan on modding your car, you can certainly do better than the T25. But the T25 can do a lot more than stock if you provide supporting mods (it's still a puny turbo, though). I'm sure most of the folks on this forum will recommend that you upgrade the turbo...then the SMIC...and the FP...and then DSMlink, etc. I'm one of them. If you decide to upgrade, I'd highly recommend that you follow the recommended order, though. Don't get a turbo until you have all of the other things. You'll be better off. Trust me.

 

[dsmzoom]

I did replace the stud, if this doesnt cure it after I port the wastegate entrance, would purchasing an o2 dump completely eliminate boost creep?

 

[Mr Peepers]

An o2 dump by itself rarely eliminates creep. The problem is often in the wastegate entrance/passage and/or flapper travel.

 

[dsmzoom]

Now I'm frustrated. I ported the WG entrance to the extent of the first thread you showed me. It did however help hold 10psi better but still creeps up to 17+ then I let off. I have dropped this turbo 3 times in the past 3 days and have spent 7 hours each day..Any other suggestions?

 

[ApexVIII]

port it and get the 34mm flapper

 

[kittay]

You can always go external/ open dump

 

[Mr Peepers]

I personally don't like 34mm flappers, and don't recommend them since they are a compromise later down the road.

Before I suggest other options such as going external, why not upgrade your fuel system and support the higher boost pressure? It would perhaps be cheaper than most of your other options, and a great excuse Seems like more of a step in the right direction.

Or
Do the boost creep test indicated in this article:
http://www.dsmtuners.com/forums/art...boost-creep-modified-wga-peepers-mod-how.html
and see if it's lower than your desired boost pressure.

Or go external.

Perhaps even add a catalytic converter or any other slight restriction back into the exhaust... I wouldn't, but hey, it could help.

 

[DSMsOwnYourV8]

I had this same problem, the route I took was an External Wastegate and I don't regret it. At least if you go external and decide to upgrade Turbo's again later, you'll be one step ahead of the game.

 

[kiddsm95]

Dunno, perhaps it was just my car. With 3" cat-back it held a steady 15 psi, then after installing the 3" dp boost went up to 20 psi.

 

[gotboostsc]

Hey guys I know that the boost creep subjects have been beaten to death, but i have a concern. I have a 1992 Talon TSi with a stock 14b and 3inch SS exhaust turbo back. When i get into third gear and punch it the car will boost up to about 12 lbs then gradually creep up to about 16-17 psi at 6,500 RPM's. I don't get any fuel cut at this point and the car pulls strong. I have an aftermarket boost gauge but no data logging capabilities. I did remove the BCS but from reading many other posts it seems that this boost seems to be a bit high. I know I should prob port the 02 housing and such but my question is, is this boost level safe with a stock fuel system, stock pump and 450cc injectors. Also shouldnt I be hitting fuel cut or no?

 

[sadc]

about fuel cut. You wont always hit it right then and there. Mines usally kicks in after awhile. I have a 97 rs-t so its not ment for turbo because of my map sensor.

 

[OneLove]

Just try not to go WOT until you figure the creep problem out, and hope that the 02 housing helps.

 

[91LaSerTurBo3]

well thee ole car is boost creeping again, and i was just wondering what are some things i could do to get rid of it for once and all, starting with the cheapest first!

 

[1999silverGSX]

Are you on the stock turbo or do you have a 16g?

 

[TxR6guy]

Also when is it boost creeping? extreme cold weather? or all the time?

 

[gsxAWDdsm692]

Curing boost creep isn't cheap, plain and simple. Mostly results in extensive turbo porting and O2 housing. Or just run external.

 

[Mr Peepers]

The cheapest way is to port the turbine housing yourself.

Here are some threads on the subject, although there are quite a bit more:
http://www.dsmtuners.com/forums/art...oler/186525-how-cure-boost-creep-porting.html
http://www.dsmtuners.com/forums/turbo-system-tech/275021-oldman-could-you-grade-my-porting.html
http://www.dsmtuners.com/forums/bolt-tech/217409-porting-my-14b-oldman-your-needed.html
http://www.dsmtuners.com/forums/turbo-system-tech/290438-rate-my-porting.html

And a post detailing how to remove the just the turbine housing with the turbo still on the car, the quickest way IMO:
http://www.dsmtuners.com/forums/newbie-forum/289309-boost-creep-s16g-ported-o2.html#post151458282

Boost creep in general and another alternative:
http://www.dsmtuners.com/forums/art...boost-creep-modified-wga-peepers-mod-how.html

Good luck!

 

[ivan300]

Get a bigger turbo