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

[007jimmy]

The one on the left has the standard aluminized steel OEM style heatshield around it and the other obviously doesnt. Should both perform the same though. Plenty of people have made good power with a 3in cat so the choice is up to you.

 

[boostednate]

So my post is a little different and I've tried searching through the forums but can't find anything particular to my situation. So here it goes, I have a 16g turbo with full 2.5" straight pipe and am getting massive boost creep. For some reason the car at low rpms will boost to about 8 pounds and hold till about 4k then the creep comes. In second gear it will creep from about 8psi to 15-16psi and in third at high rpms it will keep increasing boost till fuel cut hits. I bought an external o2 housing for it, thinking that would fix the problem but it didn't. I have my vacuum line going from my intercooler piping (j pipe) straight to waste gate. any help or input on how to kill the boost creep would be appreciated. thanks!

 

[mechanix565]

maybe try putting some washers under the wastegate actuator and porting the internal gate a bit just make sure you leave enough metal for it to seal properly

 

[Colt4G63 also]

Washers under the wastegate actuator will actually increase your boost. Grab a coolant system pressure tester, or some sort of hand pump, and see if your wastegate opens properly, and doesn't leak. Be sure to check the hose as well. I can't even run a silicone hose off my j-pipe, because it blows a big hole in it after a day or so. I had to switch back to plain rubber.

 

[boostednate]

I was thinking about porting it but dont have that much time right now. But I have a plain rubber hose going to it, I will check it tomorrow though to make sure there are no holes in it or anything. One thing I forgot to mention is my buddy was messing with the flapper arm on the wastegate and he bent it facing away from the turbo, would this have something to do with the rod that connects to the flapper arm either not opening enough, or maybe not being able to keep it open for very long?

 

[Colt4G63 also]

Did you bend it back where it should be? If it's bent a little, it should actually make the wastegate open further if anything, if it's bent 90 degrees or more, it may not open at all.

 

[boostednate]

I just bent it back where the flapper arm should be, I haven't had a chance to take it for a drive and see how it is yet but I might do it in a little bit. If that doesn't fix it then I guess my next step is porting

 

[Colt4G63 also]

I just bent it back where the flapper arm should be, I haven't had a chance to take it for a drive and see how it is yet but I might do it in a little bit. If that doesn't fix it then I guess my next step is porting

So the pressure test showed a perfectly functioning wastegate and hose that don't leak at all?

 

[boostednate]

No. I'm gonna do the pressure test tomorrow at my buddies, but I was reading that boosting too low can also cause boost creep. I think I might get a MBC tomorrow and try to up it to about 15 psi. Tons of things to rule out

 

[Paintballaa5]

Yes, another boost creep thread. But this is a little different. Let me start off by saying I have zero boost leaks, and the wastegate is fully ported.

A few months ago, I had my E316g set on 17 psi (hallman mbc) and it was running great. No creep, excellent pull. After the clutch took a dump on me using 110(24 psi), I upgraded. I had a Megan DP (2.5-3") and 3" catback. NO creep at all.

Now during this clutch failure, I also put on a 3" electric cutout right after the downpipe. Now you might be thinking this is the reason for the creep.. Hang on.
I also replaced the muffler with a stock muffler to be quiet driving back and forth to work.

Now that the clutch was broke in, I did a little pull.
Boost creep.
So I tried again with the cutout half-closed, and fully closed thinking maybe it was flowing to well. Still happened. Would the cutout be the cause, or am I overlooking something simple? I thought with it closed pushing through a stock muffler it would fix it, confirming that the cutout was the culprit, but it did not.

Any thoughts?
Sorry for the novel..

 

[gsxnate99]

The more back pressure you have the more boost creep you get. I bet if you open your cut out completely you will see the boost creep go away. Theory behind it is just like porting your housing and bigger flapper to control boost better. If you don't have anywhere for the pressure to go its got to do something. Your stock muffler is very restrictive compared to what you had on it probably so that's going to restrict flow

 

[Paintballaa5]

Im sorry I guess I didn't say I ran it fully open also . But yea, any configuration of it, it creeps.

 

[NHerron]

The more back pressure you have the more boost creep you get. I bet if you open your cut out completely you will see the boost creep go away. Theory behind it is just like porting your housing and bigger flapper to control boost better. If you don't have anywhere for the pressure to go its got to do something. Your stock muffler is very restrictive compared to what you had on it probably so that's going to restrict flow

That is so much assbackwards misinformation I'm not even going to touch this. If I wasnt on a tiny phone I would.

Best advice, do some more reading.

 

[WES_393]

That is so much assbackwards misinformation I'm not even going to touch this. If I wasnt on a tiny phone I would.

Best advice, do some more reading.

+1 to this.

Boost creep is not caused by a restrictive exhaust or "back pressure". Actually it's caused by the exact opposite: A larger, higher flowing exhaust. Less resistance from the exhaust pipe allows more exhaust gas to flow through the turbine rather than out the wastegate. It's also important to note that cold weather can contribute to boost creep since the incoming air is more dense. Either way, you need to do one of the following:

1. Install a more restrictive exhaust.
2. Port the wastegate hole.

 

[LandSpeed-DSM]

Needs more wastegate valve area and/or less pre-load

 

[Paintballaa5]

+1 to this.

Boost creep is not caused by a restrictive exhaust or "back pressure". Actually it's caused by the exact opposite: A larger, higher flowing exhaust. Less resistance from the exhaust pipe allows more exhaust gas to flow through the turbine rather than out the wastegate. It's also important to note that cold weather can contribute to boost creep since the incoming air is more dense. Either way, you need to do one of the following:

1. Install a more restrictive exhaust.
2. Port the wastegate hole.

Thanks bud. My wastegate hole is ported, and it worked perfectly before. You think with the cutout closed, on stock muffler it should not creep? Because it does.

Essentially if I removed the cutout and put my old muffler back on, it would flow better than the cutout closed..

I'm going to run a hose from waste gate actuator to the j-pipe and see if it creeps then, eliminating the controller from the equation.

EDIT: Just went and connected the waste gate to the j-pipe and it still creeps. Has to be the cutout then right?

 

[NHerron]

Thanks for clarifying Wes

I'm betting if you go back to the original setup you'll still be having problems. Because if I understand correctly your current setup should be even better for boost control. I'd double and triple check everything you did since the clutch. Unhook the wg actuator see if it still boosts.
Run your signal directly from manifold, no teeing.

My bad just read again, j pipe to wg is the way to go. Much cleaner, simpler, predictable.

Unhook the actuator to rule out a torn wg diaphragm.

 

[Paintballaa5]

Unhook the actuator to rule out a torn wg diaphragm.

Unhook the arm from the flapper and run it?

I was going to attach a "Mighty-Vac" to the waste gate nipple and see if it opens the gate, as soon as it cools down.

Nothing better to ruin your day than incinerating your arm on the radiator.

EDIT: Well the Mighty Vac only does vacuum. -_-

Anyways I hooked up a line to push air through it, and the gate open and closes freely. Is there anything in specific I should be looking for?

 

[gofer]

Like someone already mentioned, pull the wga from the flapper and go do a pull. If you build an excessive amount of boost your creeping and it's not the wga causing it. Doing this is the simplest way to determine if it's actual boost creep or a faulty part...

 

[Paintballaa5]

Like someone already mentioned, pull the wga from the flapper and go do a pull. If you build an excessive amount of boost your creeping and it's not the wga causing it. Doing this is the simplest way to determine if it's actual boost creep or a faulty part...

Thank you sir, I wasn't sure if he meant actually pull the arm from the flapper at the time. I read an article at work that said to try that though, and I will first thing in the morning.

 

[gofer]

Technically, in a efficiently working setup, the only thing that allows a turbo to build boost is the wastegate because it forces the exhaust to take the path of least resistance and flow over the turbine wheel while the wastegate port is closed and vise-versa when it opens to control boost.

To test if your wastegate actuator is creating the boost creep and not opening the flapper at XXpsi of boost you simply slide the arm off the flapper and go for a drive.

 

[Paintballaa5]

Technically, in a efficiently working setup, the only thing that allows a turbo to build boost is the wastegate because it forces the exhaust to take the path of least resistance and flow over the turbine wheel while the wastegate port is closed and vise-versa when it opens to control boost.

To test if your wastegate actuator is creating the boost creep and not opening the flapper at XXpsi of boost you simply slide the arm off the flapper and go for a drive.

So if it doesn't build boost, the waste gate actuator is at fault?

 

[Paintballaa5]

Weather finally cleared up and i disconnected the actuator rod. Stayed at 0psi for a bit, but slowly creeped back up to ~20lbs by 6k rpms. I'm all out of ideas now..

 

[forcefed86]

Weather finally cleared up and i disconnected the actuator rod. Stayed at 0psi for a bit, but slowly creeped back up to ~20lbs by 6k rpms. I'm all out of ideas now..

Who runs under 20lbs these days? Easier to do the supporting mods to run 20psi than to fix it. I say leave it as it is and enjoy it. If you don't want it to creep get a larger turbine housing. Thats your only real option at this point.

 

[NHerron]

You need more back pressure, post 02 housing, or a bigger wastegate (external) but that's a bit more custom work than just adding a cat or smaller DP. You could also have two exhaust systems by using an electric cutout. So one exhaust to control boost and be quite then flip a switch and bam 3" straight pipe max boost (tune for it of course) Watch out for knock, the 16g starts blowing hot air on the higher boost levels and pump gas won't cut it.