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

Posted by RRF900RR, Apr 5, 2002

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  1. MJcanada

    MJcanada Proven Member

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    campabello, South Carolina
    Gofer never said it would completly either. Thats what I was saying.
     

    1K  0

    1995 Mitsubishi Eclipse GST
    manual · 2G DSM
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  2. gofer

    gofer Moderator

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    Joined Feb 18, 2006
    South Gilbert, Arizona
    Thanks for muddying up the already muddy water forcefed, what you're trying to say is so much clearer now.

    We'll end this convo of confusing, bass-ackwards, and un-enlightening boost creep theory for those that want to read it with your last post and hopefully they can decipher which posts makes sense.

    Good talk.

    :dsm:
     

    Street Build 16K  12  61

    1997 Mitsubishi Eclipse GST
    11.634 @ 126.050 · 2G DSM

    2K  0

    1997 Mitsubishi Eclipse N/T
    manual · 2G DSM
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  3. forcefed86

    forcefed86 Proven Member

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    wichita, Kansas
    It was just a statement made to argue a point. But you are wrong as well. It has been done... many times. It's just not practical for a street car as I said you have to find a happy median.

    I know of several land speed as well as diesel and compound setups that operate with a huge turbo(s) and no gate. The turbo will not overspeed if it is sized properly.

    No problemo chief.... :thumb:
     
  4. MJcanada

    MJcanada Proven Member

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    campabello, South Carolina
    I guess that is somewhat what I was meaning. but idk if thats properly sized, I guess sized for its purpose. As its just the engine can't make enough exhaust flow to overflow the turbo which is, exhaust restriction. Top speed is the only way that could be done though. Which like you said its no good for the street. Anyways before anymore confusion comes, I'll just stop here.
     

    1K  0

    1995 Mitsubishi Eclipse GST
    manual · 2G DSM
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  5. LandSpeed-DSM

    LandSpeed-DSM Proven Member

    1,991
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    Joined Dec 5, 2011
    Chicago, Illinois
    [​IMG]
     

    2K  0

    1992 Mitsubishi Eclipse GST
    · 1G DSM
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  6. MJcanada

    MJcanada Proven Member

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    Joined Jun 25, 2011
    campabello, South Carolina
    Haha!
     

    1K  0

    1995 Mitsubishi Eclipse GST
    manual · 2G DSM
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  7. Paintballaa5

    Paintballaa5 Proven Member

    372
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    Joined Jan 23, 2012
    Houston, Texas
    Well gofer, going back to the old exhaust didn't help either.. :banghead:
    Anymore ideas? I'm stumped.
     

    Street Build 3K  15

    1991 Eagle Talon TSi AWD
    manual · 1G DSM
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  8. AngelOfPassion

    AngelOfPassion Proven Member

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    Joined Jul 5, 2011
    Mesa, Arizona
    Have you tried using a different o2 housing yet? I have an evo III 16g, PR Recirculated o2 housing, 2.5-3" Downpipe, No cat, 3" muffler and my 16g starts at 10psi and FALLS to around 8psi at redline.

    The only two things that have been done are 1. Porting of the turbo's wastegate area after the flapper and before the flapper in the exhaust entry area. 2. Using an o2 housing that has a less restrictive wastegate side than the stock housing.

    I have also heard from others that an aftermarket o2 housing has helped their creep issues so it isn't just me that this worked for. Worth a try if you have one laying around.
     

    507  0

    1997 Mitsubishi Eclipse GSX
    manual · 2G DSM
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  9. Paintballaa5

    Paintballaa5 Proven Member

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    Joined Jan 23, 2012
    Houston, Texas
    I don't have another o2 housing laying around. Mine is ported though, and didn't have any problems before with it. So I don't believe it's that.
     

    Street Build 3K  15

    1991 Eagle Talon TSi AWD
    manual · 1G DSM
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  10. forcefed86

    forcefed86 Proven Member

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    wichita, Kansas
    th_bloody_keyboardguy.gif
     
  11. gofer

    gofer Moderator

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    South Gilbert, Arizona
    So you were NOT seeing boost creep with exhaust setup A but when you switched to exhaust setup B you started getting boost creep. You went back to exhaust setup A and it still crept?

    Since you're running straight off the stock wastegate actuator (12psi) what is it creeping to and at what RPM does it start?

    What gear are you seeing it creep, all or just one or two?

    How is your wga line hooked up exactly and there's absolutely no boost controller in between?

    :dsm:
     

    Street Build 16K  12  61

    1997 Mitsubishi Eclipse GST
    11.634 @ 126.050 · 2G DSM

    2K  0

    1997 Mitsubishi Eclipse N/T
    manual · 2G DSM
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  12. Insane20

    Insane20 Proven Member

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    Joined Jun 12, 2012
    Natrona Heights, Pennsylvania
    what i did with my j-pipe rather than had it welded was i got a steel bolt in valve stem from the auto parts store "not a typical rubber one". the steel valve stems are used on omnie busses so they hold high pressure. they come with a valve stem, a nut, a washer and an o-ring. then just drill a hole in your j-pipe, take the valve core out and bolt it in. and since they are made of steel they look professional and work as good as a welded tap minus the cost.
     

    1K  0

    1995 Eagle Talon TSi AWD
    12.100 @ 121.000 · 2G DSM
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  13. NHerron

    NHerron Proven Member

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    Missoula, Montana
    except... it's still a valve stem on a J-pipe...?

    LOL just kiddin, good idea :thumb:
     

    1K  0

    1997 Mitsubishi Eclipse GSX
    11.230 @ 127.000 · 2G DSM
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  14. Insane20

    Insane20 Proven Member

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    Natrona Heights, Pennsylvania
    haha I will have to post a pic. it sounds ridicuous but acutally dosent look bad LOL.
     

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    1995 Eagle Talon TSi AWD
    12.100 @ 121.000 · 2G DSM
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  15. Insane20

    Insane20 Proven Member

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    Natrona Heights, Pennsylvania
    DSCF2228_zps5c096e91.jpg

    heres the pic of my tap.
     

    1K  0

    1995 Eagle Talon TSi AWD
    12.100 @ 121.000 · 2G DSM
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  16. Long live dsm

    Long live dsm Probationary Member

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    Joined Jul 8, 2013
    Lexington, Kentucky
    I been stuck about this for a while!
    I been reading about this before i even put the 16g on.
    Any ways i have a true mhi 16g on my 98! Running on a 2g o2 housing

    I get into the gas and i have steady boost for a few secs,
    Then boost spike / creep then fuel cut:(

    What am i doing wrong? I just want to run low boost till i get more mods

    Is it the 2g o2 housing wont let the any flow through the wast gate passage?
    I need help!
     

    166  0

    1997 Eagle Talon TSi AWD
    · 2G DSM
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  17. LandoAWD

    LandoAWD Retired

    4,323
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    Joined Jun 13, 2002
    Hillsborough, North Carolina
    1. Is it spike or creep?
    2. Based on your mod list, I'm going to assume creep

    Bigger flapper.
     
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  18. eDeclpse92

    eDeclpse92 Proven Member

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    Joined Sep 6, 2008
    Belleville, Illinois
    ^^^ What Lando said. Or you can get rid of the internal wastegate altogether and get an external wastegate so if you do decide to go higher in boost, you wont have to worry about boost creep. I had the same problem with my 14b. I plugged the linkage hole, reamed out the flapper hole and put on a tial 38mm and problem solved. Running 20 psi steadily in every gear and I'm going to upgrade to a 16G one day so I can just keep the same system and change out the spring if I need to on the Wastegate. Goodluck!:thumb:
     
  19. wkmitsu

    wkmitsu Proven Member

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    1999 Mitsubishi Eclipse GST
    · 2G DSM
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  20. MJcanada

    MJcanada Proven Member

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    campabello, South Carolina
    The higher the boost the less wastegate you need. Large wastegates bypass more gasses around the turbine. The more boost you run the smaller your wg needs to be because you want less exhaust bypassing the turbine.
     

    1K  0

    1995 Mitsubishi Eclipse GST
    manual · 2G DSM
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  21. Talyn

    Talyn Proven Member

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    Joined Jun 10, 2012
    Pittsburgh, Pennsylvania
    Kind of a long explanation, question is at end:
    My modification and repairing of my car was in rapid flux when I got it...seeing very little drive time between each repair/mod session... That being said, I am almost certain that when I initially put my 20g(internally gated)on and ran off of the 13 psi wastegate, that I was not fuel cutting, but it also had an aftermarket o2 housing with an open dump wastegate. Because of a major boost leak, followed by a slipping clutch, and plethora of other issues I only drove it on that setup once or twice. And in the next session of repair/modding I installed a FMIC, and during the install discovered the wastegate dump was aimed right at the intercooler output pipe, and perilously close to a boost reference line, that being said I downgraded to the factory o2 housing, not even thinking about the possibility of boost creep. Driving the car since then it seemed to almost certainly be hitting fuel cut at ~4k rpm, I thought the MBC might not be working correctly, or that maybe someone messed with it. But I double checked it and was hooked up fine. But just now while browsing exhaust systems, I came across someone stating that a 16g had a 2.5" outlet, and that the factory o2 housing was only 2" diameter(is that correct?). Causing me to wonder if perhaps ever since I switched o2 housings the car is boost creeping to the point of fuel cut because of insufficient wastegate dump? Not having a boost gauge really isn't helping me right now...its high on the list though.
     
    Last edited: Jul 29, 2013

    1K  0

    1996 Eagle Talon TSi AWD
    manual · 2G DSM
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  22. GSLENK

    GSLENK Proven Member

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    Joined May 25, 2011
    DC, Maryland
    I recently fixed all exhaust leaks and intake leaks.
    I had lowered boost to start tuning all over again. And to my surprise, I either am getting piss poor spoolup, or pretty bad boost control.

    I am eventually targeting ~25 psi so the creep is not bad, as long as I can hold boost at higher levels.

    Now It appears that I have a creeping issue. It did not exist before. A quick google search revealed what a boost spike looks like, but I would just like a confirmation.

    Logs and .JPGs attached (for easy viewing).
    In order:

    Creeping log (suspect)
    Old 2nd gear pull (compare apples to apples)
    Old 3rd gear pull (just ### yo)

    And I also added an old low boost pull. (not in the picture, but attached as a log) I honestly don't remember if this was on a 14b or 20g. (I'm pretty sure 20g). I went to my current Wastegate when I swapped the 20g in.

    It is an ebay [Wyntonm] "knockoff style" wastegate. Absolutely nothing changed since it was installed. It did work perfect at some point.

    All I did was:
    Remove all exhaust stuff (mani, turbo, o2 housing, Ext. WG)
    Cleaned and trued all flanges.
    All new OEM gaskets
    Some Copper rtv in trouble spots (WG flanges were warped. Got them very close to true, (~.005" at the peak in center of gap. A .001" feeler indicates the gap is along .5" of circumference)

    Reassemble, let RTV cure. Proceed to beat on it some more (Retune)

    I can only think of a few things causing this:

    1- Fixing all the leaks, made the turbo that much more efficient to overcome the gate (Doubt it, but I hope it is the case LOL)
    2- I didn't get the WG stem seated properly against its own fire ring.
    3- I put too much RTV and its blocking something in the wastegate area.
    4- I am a tuning retard and I have no idea what effect my terrible VE/AFR tables have on spoolup.

    I disassembled the WG and cleaned it out. I saw no visible tears in the diaphragm (I stretched it also to check). Then I reassembled it, and blew comp. air into it. No leaks, and the valve sounds to be opening and closing correctly.
     

    Attached Files:

    4K  6

    1992 Plymouth Laser RS Turbo AWD
    awd · manual · 1G DSM
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  23. Mark4g63t

    Mark4g63t Proven Member

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    Joined Jan 21, 2010
    Minneapolis, Minnesota
    What size wastegate? Did you port the flapper hole on the hot side?
     

    1K  0

    1995 Eagle Talon TSi
    11.600 @ 120.000 · 2G DSM
    Loading...
  24. GSLENK

    GSLENK Proven Member

    1,233
    48
    Joined May 25, 2011
    DC, Maryland
    38mm 2 bolt Waste-gate is off of the o2 housing.

    No porting, no flapper either.

    The other logs illustrate it running just fine before. Clean up all the old leaks, spend over $100 on gaskets (oem) and this is what I get. I'm fed up with this POS WG, but I need it to last just a few more months :pray: Then ordering a tial mvs. Till then...

    Any ideas what can cause this? I have no exh/intake leaks. Checked as soon as I had it all back together again.
     

    4K  6

    1992 Plymouth Laser RS Turbo AWD
    awd · manual · 1G DSM
    Loading...
  25. 2g spyder eclipse

    2g spyder eclipse Proven Member

    177
    1
    Joined Apr 30, 2013
    Milwaukee, Wisconsin
    I just fixed my boost creep on my evo 3 16g. I've been fighting it for a year.. But sometimes simple things seem bigger... All I had to do was put a bigger vacuum line the wastegate and pressure source = problem solved. Give it a shot!
     

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