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This is a discussion on Boost creep / fuel cut within the STi Technical Forum forums, part of the Tech & Modifying & General Repairs category; an EWG setup will require EM to modify the boost map....not the most economical setup for getting rid of boost ...

  1. #31
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    an EWG setup will require EM to modify the boost map....not the most economical setup for getting rid of boost creep...

    I'd recommend sending your turbo to Deadbolt or Crucial Racing & have them port out the wastegate professional.
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  3. #32
    Registered User TheReaper's Avatar
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    Quote Originally Posted by abtgolf
    All these boost creep topics are sooooo confusing. i read a lot about it, seems like external wg or porting wg is the best ways to go if you choose to do Catless TBE.

    but what confused me is, some ppl say it won't happen, some ppl say boost creep happened, but went away.

    I am very worry now becuase I bought a RS*R catless dp, with RS*R Exmag exhaust, made appointment to install this Thursday.
    what should I do now? i really don't know....
    should I:

    1. port the WG on the day that I am going to install the exhaust and dp?
    2. order an external wg, wait for it before i install dp or exhaust.
    3. or should i install it, drive easy on my car, gradually push a bit more on gas, see if boost creep will occur, if it does, then order the external wg, or do EM?

    what do you guys think? by the way, I have a 06' STi if this helps answer my questions.

    please help... THANK YOU!!! Thank you.. thank you.
    I just got all my parts that I ordered in last week and I've installed the short ram and TXS RFL Ti catless tbe and yeah I had boost creep everytime I hit 5th gear wot (thats when shifting at 6k-7krpms while wot in 4th). I am going to be installing my UTEC and other goodies either tomorrow or Thursday so I can tell you then if the EM does anything for the boost creep or not, or I should actually say I could tell you then if the UTEC helps with the boost creep or not. I am also waiting for my Apexi AVC-R ebc to come in so we shall see if that helps out as well.

    PS: I have no cats or resonator, I have the race pipe in place of the other shiz so my tbe consists of 4 pieces rather than the usual 3, it's just straight through pipe with no restrictions.
    Last edited by TheReaper; 05-30-2006 at 08:44 PM.
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  4. #33
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    Quote Originally Posted by TheReaper
    I just got all my parts that I ordered in last week and I've installed the short ram and TXS RFL Ti catless tbe and yeah I had boost creep everytime I hit 5th gear wot (thats when shifting at 6k-7krpms while wot in 4th). I am going to be installing my UTEC and other goodies either tomorrow or Thursday so I can tell you then if the EM does anything for the boost creep or not, or I should actually say I could tell you then if the UTEC helps with the boost creep or not. I am also waiting for my Apexi AVC-R ebc to come in so we shall see if that helps out as well.
    EM ONLY masks boost creep, boost creep is a mechanical problem that ONLY a ported wastegate can solve....

    if you cannot get enough exhaust air out of a hole it doesn't matter what kind of EM you are running.
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  5. #34
    Registered User abtgolf's Avatar
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    Quote Originally Posted by TheReaper
    I just got all my parts that I ordered in last week and I've installed the short ram and TXS RFL Ti catless tbe and yeah I had boost creep everytime I hit 5th gear wot (thats when shifting at 6k-7krpms while wot in 4th). I am going to be installing my UTEC and other goodies either tomorrow or Thursday so I can tell you then if the EM does anything for the boost creep or not, or I should actually say I could tell you then if the UTEC helps with the boost creep or not. I am also waiting for my Apexi AVC-R ebc to come in so we shall see if that helps out as well.

    PS: I have no cats or resonator, I have the race pipe in place of the other shiz so my tbe consists of 4 pieces rather than the usual 3, it's just straight through pipe with no restrictions.
    Yeah Reaper, keep me posted on your car.
    06' Aspen White STi

  6. #35
    Registered User abtgolf's Avatar
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    Quote Originally Posted by testes1010
    EM ONLY masks boost creep, boost creep is a mechanical problem that ONLY a ported wastegate can solve....

    if you cannot get enough exhaust air out of a hole it doesn't matter what kind of EM you are running.
    so much fun on modding car, but so much troubles.... AAAAHHHHHHH, i hate this.. since i bought the rs*r catless dp and exhaust already
    06' Aspen White STi

  7. #36
    Moderator YBNormal07's Avatar
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    I still think your best all around setup is to go with a high flow cat in line with the TBE. You loose maybe 5 hp total, and you will not get creep.

    For those that are confused by the supposed "fact" that some with catless TBE get creep, and others don't, I believe this is merely a matter of driving habits and ECU management. The ECU will learn about the creep and it will make adjustments, thus canceling out some of the effects, but ultimately, the creep is still there and I guarantee it just doesn't go away. Until Subaru provides a larger WG porthole, or until you opt to integrate 1 of the known fixes, there is always the chance you will get creep/fuel cut. Anything else is just wishful thinking.
    TBH...it isn't a huge deal as fuel cut prevents any engine related issues...it just feels horrible when it happens....like WTF was that!*!#*#*!*
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  8. #37
    Registered User TheReaper's Avatar
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    Quote Originally Posted by abtgolf
    Yeah Reaper, keep me posted on your car.
    Ok so I installed the UTEC and did a few pulls on the street then messed with the boost and did a few more pulls. My cel was fine for a day then came back but here's the thing about the boost creep, as some others said, em only masks the problem but I will tell you I had not 1 single knock during any of my pulls going wot from a 3rd gear 3,000rpm pull all the way through the beggining of 6th gear. After messing with my boost I am hitting mid 16psi starting at about 3,500-4,000rpms through 6,500 rpms then it drops to mid 14psi range for the last 500rpms and when I hit 5th gear wot where boost creep would stall the engine the car keeps pulling with no knock........ however my boost does spike to 19psi for a second or so then goes back down to mid 16psi range (when doing low rpm pulls or going from a dig my boost is about 12.5-14.5 starting at about 2,000-2,500rpms until I hit full boost). I'm gonna be installing an Apexi AVC-R ebc in place of the UTEC mbc in about a week but all I can say is my car pulls hardcore now, with a tune I should be running pretty hard.
    Last edited by TheReaper; 06-02-2006 at 01:00 PM.
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  9. #38
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    Quote Originally Posted by TheReaper
    Ok so I installed the UTEC and did a few pulls on the street then messed with the boost and did a few more pulls. My cel was fine for a day then came back but here's the thing about the boost creep, as some others said, em only masks the problem but I will tell you I had not 1 single knock during any of my pulls going wot from a 3rd gear 3,000rpm pull all the way through the beggining of 6th gear. After messing with my boost I am hitting mid 16psi starting at about 3,500-4,000rpms through 6,500 rpms then it drops to mid 14psi range for the last 500rpms and when I hit 5th gear wot where boost creep would stall the engine the car keeps pulling with no knock........ however my boost does spike to 19psi for a second or so then goes back down to mid 16psi range (when doing low rpm pulls or going from a dig my boost is about 12.5-14.5 starting at about 2,000-2,500rpms until I hit full boost). I'm gonna be installing an Apexi AVC-R ebc in place of the UTEC mbc in about a week but all I can say is my car pulls hardcore now, with a tune I should be running pretty hard.
    Just inspect your turbo flanges very closely to be sure you aren't cracking them. At 19 psi peak, you are above the efficiency range and your poor turbo is spinning like mad.....I'm sure it's been a pretty cherry red a number of time already. Look for hairline cracks as they VF39 has been known to do this....and I suspect it is because of higher boost levels after modding. No big worries, as they seem to function fine even with the cracks.

    Also..it sounds like the UTEC moved the fuel cut limit upwards. Might want to verify this. Are you logging your AFRs?
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  10. #39
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    Quote Originally Posted by YBNormal07
    Just inspect your turbo flanges very closely to be sure you aren't cracking them. At 19 psi peak, you are above the efficiency range and your poor turbo is spinning like mad.....I'm sure it's been a pretty cherry red a number of time already. Look for hairline cracks as they VF39 has been known to do this....and I suspect it is because of higher boost levels after modding. No big worries, as they seem to function fine even with the cracks.

    Also..it sounds like the UTEC moved the fuel cut limit upwards. Might want to verify this. Are you logging your AFRs?
    Yeah we were, my friend had the laptop and that's how I was doing everything but he just went back to New Mexico because he was on leave for only 2 weeks. I think I am gonna buy a laptop sometime within the next 2 weeks so I can monitor everything. Yeah I didn't like the fact that the boost spikes to 19psi for a second but since I rarely hit 5th wot it won't be to bad until I port the wg or upgrade the turbo and switch to ewg. I'll be checking out the turbo everyday to just keep an eye on everything. I think I am gonna have Crawford Performance port my turbo (if they do that) because I am most likely gonna have them tune my car so I might as well get that done too.
    You might be a king or a little street sweeper but sooner or later you'll dance with the reaper.

  11. #40
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    It seems to me that there is another logical answer.

    I understand that no engine management system can deal with the mechanical problem of boost creep. It is basically just a result of an overload of the overall system.

    However, I don't understand why no EMS has come up with a system to simply emliminate the ECU's response to boost creep. It seems plausible that the CEL which results from it, as well as the fuel cut, could simply be removed. Although they are safety features which keeps the motor from leaning out too much, it seems that the mods which cause this to happen aren't severe enough to really risk damaging the motor due to an overboost or overlean situation.

    Is my logic wrong here or is there something that I am missing?

    Jon
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  12. #41
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    Quote Originally Posted by Jon @ Kinesis
    However, I don't understand why no EMS has come up with a system to simply emliminate the ECU's response to boost creep.

    Jon
    I forgot i was subscribed to this thread. To recap my situation, i started getting creep with my 3" catless TBE. I went with the Cobb AP stage 2 maps and my creep went away. My boost stays steady around .12 bar even in WOT in 5th and 6th gears.

    Problem solved. I've been very happy ever since.

  13. #42
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    Quote Originally Posted by 409industries
    I forgot i was subscribed to this thread. To recap my situation, i started getting creep with my 3" catless TBE. I went with the Cobb AP stage 2 maps and my creep went away. My boost stays steady around .12 bar even in WOT in 5th and 6th gears.

    Problem solved. I've been very happy ever since.
    You don't happen to have before and after dyno's for that do you? I'd be curious to see the wastegate duty cycle in comparison to boost levels before and after.
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  14. #43
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    Quote Originally Posted by Jon @ Kinesis
    It seems to me that there is another logical answer.

    I understand that no engine management system can deal with the mechanical problem of boost creep. It is basically just a result of an overload of the overall system.

    However, I don't understand why no EMS has come up with a system to simply emliminate the ECU's response to boost creep. It seems plausible that the CEL which results from it, as well as the fuel cut, could simply be removed. Although they are safety features which keeps the motor from leaning out too much, it seems that the mods which cause this to happen aren't severe enough to really risk damaging the motor due to an overboost or overlean situation.

    Is my logic wrong here or is there something that I am missing?

    Jon
    You wouldn't be concerned about overboosting the turbo and creating an overlean condition? Remember, it is the fuel cut that stops the overboost condition. If you elimante the fuel cut, who knows who high the boost can go since this is a feedback situation...the more boost you make, the more boost you make. Sure there is a efficiency issue here and that could theroetically be the limit at which air is stuffed into the engine, but now you are also looking at the issue of the turbo itself. Stress from the overboost condition won't be good for the turbo. And remember, the mods involved to not include rasing the fuel pressure or flow, so there is a risk of burning out the rings. The valves should be fine in this case due to construction materials, but the rings aren't anything exotic. This doesn't even get into the pre-det conditions that exist on a lean running engine at high RPM where the high boost is occurring. Some EMS does move the fuel cut to a boost level/time duration though, so perhaps this is the direction you are thinking?
    tEh PriUs=teH faSTah!@@!
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  15. #44
    Registered User Jon @ Kinesis's Avatar
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    That is kind of the way that I was thinking. I just noticed from looking at a lot of AF maps generated by people running most of the Cobb Stage 2 setups that they are very rich on the top end.

    It seems logical that as long as your EGT stays within spec that the overboost condition isn't leaning out the motor too bad, since it was running rich to begin with.

    Now it is true that we don't know exactly how high the boost will spike, but it seems plausible, especially running with the stock VF39 that at somewhere around 18psi that it is running out of steam. There shouldn't be a whole lot more room left in it really.

    More accurately, the way I was thinking was that if you were experiencing the fuel cut due to boost creep in very specific situations, that by removing that fuel cut but still being wary of those situations, you could protect your engine through your own active thinking without experiencing those side effects. For instance, it was mentioned that someone here only experienced it when they were on the track. If you were cognizant of that fact, you could simply pay attention to it in situations where you would normally experience some creep, and lift slightly rather than have to worry about the ECU taking over and cutting fuel completely.

    Jon
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  16. #45
    Registered User StupidMan's Avatar
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    The problem with boost creep is there is usually no way to know exactly when its going to happen. Even with monitoring every parameter of your engine, as well as outside parameters such as baro pressure, humidity, temp, altitude ect ect it would be nearly impossible to predict.

    It would be equally impossible to simply back off of the throttle to avoid boost creep. By the time your boost guage shows the spike, it could already be too late (especially when you factor in the 1/8-1/2 second it takes for your brain to respond). 1 pre-ignited cylinder can blow your engine. That happens in about 1/1000th of a second.

    That is almost like surgically removing a kids voice box to keep him from screaming about a broken leg.

    The best idea listed on this board is probably the simplest....get a high flow cat. The second easiest thing would be port the WG. Maybe even a baffle in the exhaust would work.
    stupidman has spoken

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