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

[Dan97gst]

Last night me and a buddy installed a 3in downpipe with the orginal cat and 3 in catback exhaust on my car. We have a upgraded o2 housing but ran out of time to put it on so we left on the stock one. Everything else is stock on the car except a hard pipe intake. So when we went out for a test drive, I got on the gas and I hit fuel. Could this be from the new exhaust, or that I need on the o2 housing. It was also very cold out last night if that helps any. He thinks it is boost creep, and he thinks i should reset my ecu. Would reseting the ecu help at all or do I need to hurry up and put on the o2 housing. Thanks

 

[Glliw]

So this is the completely stock car except exhaust and intake? No boost controller right? The bigger exhaust is letting it flow more exhaust, so you might be getting 1psi or 2 more.

 

[John_GST]

So this is the completely stock car except exhaust and intake? No boost controller right? The bigger exhaust is letting it flow more exhaust, so you might be getting 1psi or 2 more.

True. Yoy shouldn't be getting much boost creep, if you are, since everything on the car is stock. Just in case you are getting creep its due to the exhaust. The three inch exhaust is making the turbo flow better and in result wanting to boost more. Still with stock turbo and stock boost controller you wont be getting much creep with it. Good luck.

 

[nightspeed87]

My 14b would creep once I did full 3in exhaust ( no muffler ) and even worse on open dp. It would hold 15psi till 5k in and creep to like 17 by redline in 3rd gear and up.
I had a stock 02 housing at the time and the interal wastegate flow on that wasnt very good so I suspect thats why. Depending on the o2 housing you have to still put on, it should creep less after you put it. Also word of advice, port it out before you put it on like I did, and you can almost eliminate creep. Porting enhances flow obviously but the trick is to port the actual waste gate section of the o2 housing where the small hole reroutes back to the main turbine exhaust hole. It physically is too small to control boost once VEs start to increase thats why it needs to be ported. www.Vfaq.com I think has a write up on it.

 

[romeen]

Since you are beginning to modify things you should get an aftermarket boost guage. Being able to monitor your boost levels will tell if it boost creep (it does sound like it) and will open the door to further modifications which I'm assuming you're interested in since you are a member of the forums.

 

[kmoore]

Since you are beginning to modify things you should get an aftermarket boost guage. Being able to monitor your boost levels will tell if it boost creep (it does sound like it) and will open the door to further modifications which I'm assuming you're interested in since you are a member of the forums.

+1= You absolutely need a aftermarket boost gauge with numbers. I completely agree with Romeen %100. It doesn't even sound like its creep. For all he knows he could just have a massive boost leak and is just stuttering under boost and THINKS its "fuel cut"

 

[oldman]

I wanted to make my 8000th post some what meaningful, guess this will do.

BOOST LEAK TEST!!!!

 

[ILLiCliPSE]

Im assuming youre still on the stock T25. This turbo is known to spike a lot...if you hold that spike for too long, you'll hit fuel cut. The MAS is reading a spike in airflow, and is cutting fuel. The same exact thing happend to me when I installed my exhaust while I was on the T25. I wouldnt say its creep, more like a spike. At what RPM do you hit fuel cut (if it even is fuel cut)

Do a boost leak test and get a boost guage.

 

[Dan97gst]

ok I did do a boost leak test a couple of weeks ago but I guess it is time to due another. The o2 housing that we still have to install is an aftermarket one that is fully ported out, so hopefully that will make a difference. It hit fuel cut around around 4k or so or just about a sencond after it was up to full boost. It does sound like spiking to me now that I think about it. My buddy is selling his car so I will be slowly getting upgraded puts off of his car like 550, T28, fuel pump, and afc controller. Thanks for Advice

 

[1999silverGSX]

I have a 99 GSX a/t and i just ordered a MHI EVO3 16g

I have The Following Parts
- 190lph fuel pump
- 650cc injectors
- Apex-i Safc Neo
- Just Ordered MHI Evo3 16g

I know i need to get a FMIC set-up and a Logger Set-up, The main thing im worried about with this turbo is the infamous boost creep. I know you can solve this problem 3 way. One, Port the wastegate passage area, Two, Go external wg on manifold, Three Run 20+ psi of boost . My question What would it take to run 20psi of boost so i dont have to worry about boost creep?

Thanks in advance and information is greatly appreciated.

 

[v2ner]

I have a 99 GSX a/t and i just ordered a MHI EVO3 16g

I have The Following Parts
- 190lph fuel pump
- 650cc injectors
- Apex-i Safc Neo
- Just Ordered MHI Evo3 16g

I know i need to get a FMIC set-up and a Logger Set-up, The main thing im worried about with this turbo is the infamous boost creep. I know you can solve this problem 3 way. One, Port the wastegate passage area, Two, Go external wg on manifold, Three Run 20+ psi of boost . My question What would it take to run 20psi of boost so i dont have to worry about boost creep?

Thanks in advance and information is greatly appreciated.

To run 20psi...you'll need a great tune. I've done it before. Other stuff that will help reduce knock will be a FMIC, NGK BPR7ES plugs, higher octane fuel/alky injection. Around 18psi is where pump gas starts to detonate.

It's useless to run this boost level w/out a FMIC because the stocker will heatsoak and smaller turbos also produce more heat.

Boost creep usually goes to ~23psi on this turbo. You don't need to go external WG to stop it. Here's what I did when I had this turbo: ported turbine housing inlet, ported Ex. manifold, ported wastegate, 34mm flapper upgrade.

 

[1999silverGSX]

I have heard that the 34mm flapper upgrade wasnt a good idea if i wanted to run high boost.. because it allows the wastegate to open easier?

 

[v2ner]

I don't know who you heard this from but I'm someone who likes to max out all my turbos before I upgrade. I did 30psi(goes down to 26 around 6700RPMs) and there wasn't a problem.

 

[SnowBird]

Port the flapper, and port the hell out of the O2 housing. OR, just buy a atmospheric O2 dump.

 

[my98gsx]

I ran an EvoIII 16G all last year and to tell you the truth my 14B had more boost creep than the 16G. Its a good turbo i dont think you will have a problem. If it starts to be an issue just turn the boost down untill you get the proper parts for your car. If you are going from the T25 to the 16G youll see a huge difference even without high boost numbers.

 

[SnowBird]

Do you still have a cat? That could cause it with 3" exhaust.

 

[JohnCIV_Talon]

Hi, not being a smart ass, but I am interested to know how its caused cause of no cat.

 

[Rob10_99]

the less restriction, the more boost you will see sooner,
basically more flow of exhuast and more energy is being used from your exhaust.
regulate accordingly

 

[DSMunknown]

I have heard that the 34mm flapper upgrade wasnt a good idea if i wanted to run high boost.. because it allows the wastegate to open easier?

No. The rejection of an "upgraded" flapper valve is because at higher boost, the larger valve impedes on the exhaust gases rushing past it, and thus it is more likely that one would experience boost creep because of this.

If you do some searching I'm sure you'll find some great information on this very topic.

 

[oldman]

the less restriction, the more boost you will see sooner,
basically more flow of exhuast and more energy is being used from your exhaust.
regulate accordingly

Not exactly.

Free flowing exhaust or lack of CAT doesn't cause boost creep, it simply reveals it. What causes boost creep is the poorly designed wastegate path (both in flow characteristics and capacity) of the turbine housing, specifically the Mitsu turbine housing in this case. The reason larger exhaust (or lack of CAT) reveals this problem is because air will always flow in the direction with the least resistance therefore although the wastegate flapper is open, exhaust gas still chooses to flow in the direction of the turbine path instead of the wastegate path.

 

[oldman]

Port the flapper, and port the hell out of the O2 housing. OR, just buy a atmospheric O2 dump.

An O2 dump rarely cures boost creep and is not necessary because the biggest contributor to boost creep is the poorly designed flowing characteristics of the wastgate path in the turbone housing, specifically the Mitsu turbine housing.

No. The rejection of an "upgraded" flapper valve is because at higher boost, the larger valve impedes on the exhaust gases rushing past it, and thus it is more likely that one would experience boost creep because of this.

Sorry Anthony, the issue with a larger flapper is its ability to hold back exhaust back pressure due to increase in surface area. When does a particular size flapper gets blown open will however vary from car to car since the amount of exhaust pressure present, given the same intake pressure and turbo, depends greatly on ambient temperature, barometric pressure, cooling efficiency, VE and exhaust system.

If it starts to be an issue just turn the boost down untill you get the proper parts for your car. If you are going from the T25 to the 16G youll see a huge difference even without high boost numbers.

The result of boost creep is that you can't run lower boost level, the lower you try to set your boost, the quicker you reach full boost, the more time and rpm range to creep, the worse the creep. Your statement doesn't make sense.

1999silverGSX, http://www.dsmtuners.com/forums/showthread.php?t=186525

 

[hereitcomes]

With the 16g and 14b you will start to creep if you run lower boost levels. Im running 9lbs with ported 16g o2 housing and ported 2g manifold. Im running a blow thru setup and I hit full boost at about 3k, and I cant even redline it in anything past 1st. I bury the needle on my 20PSi gauge and have hit fuel cut by accident. Since its a smaller turbo I would run an external gate, along with a boost controller.

 

[oldman]

Since its a smaller turbo I would run an external gate, along with a boost controller.

Spending $400+ just to run low boost on a small turbo is a complete waste of money when proper porting can easily resolve it. Contrary to popular belief, where external wastegate is worth its cost is in running higher boost levels with larger turbos where holding the flapper shut, as well as flow capacity, becomes a major issue.

 

[DSMunknown]

Sorry Anthony, the issue with a larger flapper is its ability to hold back exhaust back pressure due to increase in surface area. When does a particular size flapper gets blown open will however vary from car to car since the amount of exhaust pressure present, given the same intake pressure and turbo, depends greatly on ambient temperature, barometric pressure, cooling efficiency, VE and exhaust system.

Bruce, you're going to have to convince me as to why a larger flapper valve would not impede on the exiting gases when the volume and speed at which the gases are moving is (pressumably) always increasing at WOT. I think I agree with what you have said, but I also think this impediment is yet another cause of boost creep.

Your second sentance is a little confusing (grammar-wise) so if you could possibly clarify what you meant that would be great.

 

[blazebolt]

I ported the inlet of my EVO3 16G using the tech article in the turbo section. No boost creep at all. For a while I had the wastegate actuator hooked up directly to the J-Pipe nipple (no boost controller) and was holding 9psi all the way to redline. My injectors were getting cleaned which is why I didn't have my MBC hooked up. Even if you don't have any porting tools (all you need is a die grinder and the bit), it's cheaper buying them and porting it yourself than any other cure.