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

[91LaSerTurBo3]

im having the same problem on my car, but i have 3" exhaust, but im going to end up porting the o2 housing, why dont you do that instead of buying new o2 housing?

 

[nfernotalon]

I will try hooking up the vacuum line that way, it shoudnt be creeping in the first place, I have the stock turbo and had the stock exhaust, now i have a 3 in catback but it did before the exhaust and dont know why.

It started happening after i adjusted my timing, it was off by a bit and set it right..

I will do the vacuum line tomorrow thanks..

 

[rrussell]

I will try hooking up the vacuum line that way, it shoudnt be creeping in the first place, I have the stock turbo and had the stock exhaust, now i have a 3 in catback but it did before the exhaust and dont know why.

It started happening after i adjusted my timing, it was off by a bit and set it right..

I will do the vacuum line tomorrow thanks..

Was your timing way advanced.

 

[nfernotalon]

It was bone stock when i bought it, dont know why it was off just by a hair not way off.

 

[nfernotalon]

Ok guys I hooked up the vacuum line from the J pipe to the WGA and I got 9psi constant no boost creep, so that means my MBC is not working correctly right? I bought a good quality MBC so this wouldnt happen and this does... seems like ebay parts sometimes are the best bang for your buck..

Does anyone have any experience with the turbonetics MBC? Can it come apart?

 

[nfernotalon]

I took apart my MBC and it seems to be working fine i blow air in it fully closed and no air goes through, as I open it air starts to go through so im assuming its working fine, but as soon as i hook it back up to my car it starts to creep!! WTF is going on?

 

[nfernotalon]

Anyone... Kenamond youve been my hero on this thread...where are you??

 

[kenamond]

Can you post a picture of your MBC? There are two general types: bleeder and ball-spring. They operate almost exactly opposite each other.

A ball-spring MBC blocks the boost signal from the j-pipe by holding a ball against an orifice with a spring until the boost is "strong enough" to move the ball out of the way and let the WGA know to open. So the more you tighten the MBC (compress the spring), the harder that ball is held against the orifice and the higher boost you get before the ball moves out of the way and lets pressure go to the WGA and open the WG. In that case, you want to turn the knob so that the spring is *less* compressed in order to lower the boost.

On a bleeder MBC, it is just an intentional leak that bleeds off boost pressure from the j-pipe so that the WGA doesn't see as high of pressure as what the compressor is generating. In this case, the looser you make it, the more it bleeds, and less pressure makes it to the WGA, so you get higher boost.

So if it's a ball-spring MBC, you want to decrease the compression on the spring (if you can take it apart, you can probably figure out if A) it's a ball-spring MBC and B) which direction you need to turn the knob). Usually, lefty-loosey will decrease boost, but I'd make sure.

And if it's a bleeder MBC, you want to bleed *less* air to lower boost (if you bleed *no* air, it should "show" the WGA the exact same pressure that is at the j-pipe, which should limit boost to 9psi in your case just as if you had a vaccuum line straight from the j-pipe to the WGA).

Note that all ball-spring MBCs have a small bleeder hole that is on the same side of the ball as the WGA. If the ball gets pushed out of the way, the boost will "fill" the rest of the MBC and the WGA vaccuum line with pressurized air. If the boost drops and the ball re-seats on the orifice, you need to let that trapped, pressurized air out of the WGA vaccuum line, or it'll never close the WG. It has another important role as well, but that's a very complicated discussion that you probably don't want to hear and don't need to care about for this particular problem.

On a final note, if turning the MBC all the way one way caused you to overboost, you could always try turning it all the other way and testing it out. Just be careful on the gas pedal and watch your boost. Don't let it go past 15psi or so.

EDIT: Forgot to mention the most common source of these problems: If you hook up a ball-spring MBC backward, it can cause this problem. In that case, the spring *and* the boost pressure are holding the ball against the orifice, so it just never opens. I'd check that first if you know it's a ball/spring MBC.

 

[nfernotalon]

Its definately not a ball and spring type I took it apart and had a spring but it had kinda like a valve, like a blow off valve where it opens and closes.

Also it says on top of the + and -

 

[kenamond]

Its definately not a ball and spring type I took it apart and had a spring but it had kinda like a valve, like a blow off valve where it opens and closes.

Also it says on top of the + and -

Usually, "oldman" shows up in these sorts of threads and can tell about bleeder type MBCs, but I think it might still be the same concept as a ball-spring, except the ball is more sophisticated. If you can tell by looking at it which nipple is which, you can probably figure it out. The valve is holding a "door" closed from the spring side. On the other side of that "door" or valve is where the boost pressure source nipple should connect. On the other side (spring side) of the valve is where the WGA nipple should connect. And if I had to guess, the "+" would be the high pressure side (boost side) and the "-" should be the WGA side. One way to tell is to loosen the spring all the way (but not so that it comes apart) and try hooking it up that way. Or maybe it's obvious just by looking at it and considering what I've just said. If that doesn't work, swap the vaccuum lines on the MBC and try it that way. Just be careful when you test it out so that you don't overboost.

 

[90tsidude]

ok, for the past 2 weeks ive been working on my 90 tsi. i got an evo3 big 16G, Evo3 02 housing. and installed a FMIC. yes it is a real MHI evo316g. thanks to extreme psi! they rock. now, my 14b was getting boost creep, i figured it was my o2 housing. so when i upgraded, i just got to take it out today and i get WOT anything about 4K its creeping. i have boost source straight to wastegate. mods are, FMIC UICP, Dejon intake pipe, lower honeycomb removed and no silencer in MAF and 2.5 no cat back. so from the turbo i have 2.5 back ### the evo 3 02 housing is 2.5. i don't know what else the problem is. any help would help my foot get back to the floor!

 

[FlatBlackAndy]

Check out your waste gate actuator and flapper. Make sure it is properly working. You should be able to get a pair of pliers on there and see if the spring feels weak. You can also do a boost leak test to see if it opens. That would also help you find any vaccum leaks you might have.

 

[90tsidude]

everything works perfectly its breand new out of the box. has 10 miles on it.

 

[FlatBlackAndy]

http://www.dsmtuners.com/forums/newbie-forum/276946-why-am-i-getting-boost-creep.html

That thread helped me solve my boost creep! If you read through you'll find this...

Just keep in mind that the compressor outlet provides a boost signal. This goes through a vaccuum line to the MBC. Then another line goes to the WGA. The actuator arm goes from the WGA to the lever on the turbine housing. The lever turns the WG flapper and releases backpressure upwind of the turbine wheel, thus limiting how much exhaust flow it gets and therefore how much boost the compressor wheel (on the other end of the shaft) will generate as a result. Something in that chain of parts isn't doing what it's supposed to. Could be a cracked/leaking vaccuum line between the MBC and the compressor outlet or WGA. Could be the MBC isn't set right or is faulty. Could be the WGA is bad. Could be the actuator arm is binding on something (heat shield). Could be the WG flapper isn't opening enough to limit boost (boost creep). Just eliminate potential problems methodically.

Wise words from a Wiseman

 

[nfernotalon]

Ha ha thats my thread^^ still cant figure it out..

 

[HIGHPSI4]

If you have a 2.5" 2 stud EVO III o2 housing you will still need to port the wastegate passage inside the o2 housing where it comes back into the exhaust path. Also, on the turbo, grind some of the exhaust housing away so that the wastegate flapper arm will open fully.

 

[Mr Peepers]

What do you mean by 2.5 no cat back? What psi are you creeping to? I assume you are hitting ~10 psi then at 4k it starts creeping?

The spring etc won't affect if it creeps or not. The problem lies in either the wastegate entrance(90* turn), the flapper(size, how far it opens), and the piping behind the wastegate and turbo. Generally, the more free flowing the exhaust is(no cat, 2.5-3 turboback etc) the more likely it is to creep. Taking the turbo off and porting with Oldman's method may be the best solution. http://www.dsmtuners.com/forums/art...oler/186525-how-cure-boost-creep-porting.html

Do a test with the wastegate arm off of the flapper(so the flapper is freely swinging) and run it up to redline or so in second or third gear. You shouldn't build any boost until the later rpms, and reach ~5-10 psi max by redline. Of course, let off if you start to creep past a safe psi. If it helps, then this may work: http://www.dsmtuners.com/forums/turbo-system-tech/267309-evo3-16g-boost-creep-solved.html

 

[SethA]

Mr Peepers is right on, Oldman has a pile of posts on this and there are pictures that show what is needed. Post some pics of your own porting when you are done and before you go through the trouble of puting it back together if you are nervous.

Seth

 

[kenamond]

I'm of the impression that the "reason" e3b16g with upgraded exhaust creeps so often is the damned WGA. It doesn't open the flapper enough at full-throw. That means the exhaust tries going out the back door (WG port), smacks into the partially open flapper, then splatters on the divider in the turbine housing. That rough trip out the back door doesn't flow well enough to divert enough exhaust around the turbine to limit boost. Porting, larger flapper, removing divider notgood:), adding a cat notgood:) are all band-aids. The 400lb gorilla in the room is the huge part-open flapper. But it's one of those parts that is a major pain in the ass to mod and extend its throw.

And disconnecting the WG arm from the WG flapper lever may actually fool you into thinking you don't have a creep problem. With the arm off the lever, the WG flapper can open 90°. If you creep in that case, I think porting is the solution. But if it doesn't creep in that test, it doesn't mean that you don't have creep. Next time you boost leak test, pressurize and watch how much the WG lever turns. That's how far it's turning when you're at full boost. If it's only 30° or even 45°, then that flapper is still very much in the way of the WG exhaust flow.

Ha ha thats my thread^^ still cant figure it out..

Last exchange in that thread had it narrowed down to your MBC. Either the MBC's faulty, it's not adjusted correctly, or it's installed incorrectly. You haven't replied to my final suggestions. I still stand by what was quoted above w.r.t. creep-like symptoms.

 

[Asimmons90GSX]

Alot of evo3's have boost creep problems...my bros car does it

 

[JusMX141]

Also, on the turbo, grind some of the exhaust housing away so that the wastegate flapper arm will open fully.

A complete waste of time. Have you ever paid attention to how far the flapper arm moves when the actuator pushes it?

 

[nfernotalon]

I'm of the impression that the "reason" e3b16g with upgraded exhaust creeps so often is the damned WGA. It doesn't open the flapper enough at full-throw. That means the exhaust tries going out the back door (WG port), smacks into the partially open flapper, then splatters on the divider in the turbine housing. That rough trip out the back door doesn't flow well enough to divert enough exhaust around the turbine to limit boost. Porting, larger flapper, removing divider notgood:), adding a cat notgood:) are all band-aids. The 400lb gorilla in the room is the huge part-open flapper. But it's one of those parts that is a major pain in the ass to mod and extend its throw.

And disconnecting the WG arm from the WG flapper lever may actually fool you into thinking you don't have a creep problem. With the arm off the lever, the WG flapper can open 90°. If you creep in that case, I think porting is the solution. But if it doesn't creep in that test, it doesn't mean that you don't have creep. Next time you boost leak test, pressurize and watch how much the WG lever turns. That's how far it's turning when you're at full boost. If it's only 30° or even 45°, then that flapper is still very much in the way of the WG exhaust

Last exchange in that thread had it narrowed down to your MBC. Either the MBC's faulty, it's not adjusted correctly, or it's installed incorrectly. You haven't replied to my final suggestions. I still stand by what was quoted above w.r.t. creep-like symptoms.

will respond today thanks...

 

[nfernotalon]

Ok so I think the MBC is working fine if blow air through it with it turned all the way closed no air goes through.. If i slowly open it as I blow air through it air starts to pass through so its working correctly right? Its hooked up the same way it was when they first installed it, before I had boost creep, I never took it off until now to check it.. or even turned it up til i bought a boost gauge..

When I did try to turn it up, no matter how high I turned it, even all the way it wouldnt go past 12psi, could this be part of the problem?

 

[SethA]

I'm of the impression that the "reason" e3b16g with upgraded exhaust creeps so often is the damned WGA. It doesn't open the flapper enough at full-throw. That means the exhaust tries going out the back door (WG port), smacks into the partially open flapper, then splatters on the divider in the turbine housing. That rough trip out the back door doesn't flow well enough to divert enough exhaust around the turbine to limit boost. Porting, larger flapper, removing divider notgood:), adding a cat notgood:) are all band-aids. The 400lb gorilla in the room is the huge part-open flapper. But it's one of those parts that is a major pain in the ass to mod and extend its throw.

And disconnecting the WG arm from the WG flapper lever may actually fool you into thinking you don't have a creep problem. With the arm off the lever, the WG flapper can open 90°. If you creep in that case, I think porting is the solution. But if it doesn't creep in that test, it doesn't mean that you don't have creep. Next time you boost leak test, pressurize and watch how much the WG lever turns. That's how far it's turning when you're at full boost. If it's only 30° or even 45°, then that flapper is still very much in the way of the WG exhaust flow.



Last exchange in that thread had it narrowed down to your MBC. Either the MBC's faulty, it's not adjusted correctly, or it's installed incorrectly. You haven't replied to my final suggestions. I still stand by what was quoted above w.r.t. creep-like symptoms.

You may well be right, what you say makes sense. I have seen other suggestions for fixes that allow the flapper to open more but I don't remember anyone saying "yes, this worked for me".

Porting did work for me and would seem to be less of a performance compromise than some of the other band-aids (like adding exhaust restriction). I would love to see a good definitive resolution to the 14b/16g boost creep issue that was as simple as a modification to make the flapper open more. All those little porting slivers suck!

Seth

 

[dsm-onster]

I have seen other suggestions for fixes that allow the flapper to open more but I don't remember anyone saying "yes, this worked for me".

Yes, Mr Peepers more-flapper-throw actuator worked for me. You can go through the thread an do it yourself if you're a decent welder and up for the work: Evo3 16g Boost Creep-Solved?.

But, I recommend giving him a pm if you have a creep problem that goes away when disconnecting the actuator. I believe kenamond. It most likely will be remedied by a longer throw actuator (a more open flapper). And he does good work. You'll get nifty adjustable wastegate actuation out of it all, too.