Boost creeper. mods MBC. Ported flapper

[Buurma]

Heyy ppls I has a 1g with some boost creep, all i could find is if you port your wasetgate flapper it should go away.. so lemme give ya the story.
Trying to save gas, turned my boost down, was at 20 with supporting mods, i turned my bucshur mbc down a few turns so now she's at about ten. if i lay into it she spikes at 15 but hits ten, then creeps up to 15-18ish.. whats my issue? turbo is EvoIII 16g ported i/o 34mm flapper- ported evo exh mani- evo 02 housing ported to hell- Apexi N1 full 3"

I Know of one boost leak, the coupler Right from the turbo elbo to the intercooler pipe. is that my cause?

 

[doctor_shock10]

The boost creeps higher at high rpm's because there's too much exhaust flow for the wastegate hole to bypass.

fyi your not going to save any gas by turning the boost down, you save gas by just keeping your foot out of the pedal. im almost positive you wont notice a diff. between 20psi and 10psi in gas money. i drive 120 miles a day and my talon has 377whp now and i get 28mpg on 20psi, i just dont drive all crazy and use my curise control as much as possible.

you could go to external wastegate off the o2 housing and never have a problem with creep.

 

[Buurma]

The boost creeps higher at high rpm's because there's too much exhaust flow for the wastegate hole to bypass.

fyi your not going to save any gas by turning the boost down, you save gas by just keeping your foot out of the pedal. im almost positive you wont notice a diff. between 20psi and 10psi in gas money. i drive 120 miles a day and my talon has 377whp now and i get 28mpg on 20psi, i just dont drive all crazy and use my curise control as much as possible.

you could go to external wastegate off the o2 housing and never have a problem with creep.

Man you know i was hoping you WOULDNT say that i'm averaging 18ish and contemplating selling her off so i can save some gas. knew it'd be bad but didnt think it'd be as bad as my truck..

and i'ma have to find out how to do that one of these days
thanks

 

[doctor_shock10]

well my 28mpg is all hwy is your dsm tuned cause if it doesnt have a good street tune it wont drive to its ablity. and i have a turbo that doesnt hit 20 pounds til 4000 rpms so that help to, so i dont hit boost at all on the hwy

 

[Buurma]

As far as i know no, but the ecu does have stutterbox and a whole buncha other stuff done. none of it makes sense to me but it ###### does to most others haah.

 

[cjridert1]

You have a 3" exhaust- this isnt much of a restriction and it easy enough that the gas would just as soon travel past the turbine rather than dip off in the waste pipe. If you pull the turbine housing off and get at it so the flapper opens farther and help the exhaust airflow with some kind porting, you may be in business to have better gas mileage during WOT pulls (1.3mpg vs .9mpg??). To run lower boost, ea$iest way is to go with an external waste setup or switch back to a smaller downpipe.

 

[Buurma]

You have a 3" exhaust- this isnt much of a restriction and it easy enough that the gas would just as soon travel past the turbine rather than dip off in the waste pipe. If you pull the turbine housing off and get at it so the flapper opens farther and help the exhaust airflow with some kind porting, you may be in business to have better gas mileage during WOT pulls (1.3mpg vs .9mpg??). To run lower boost, ea$iest way is to go with an external waste setup or switch back to a smaller downpipe.

oook? as far as i know a ported 34 mm flapper, not enough? I dunno barely anything about turbos as far as mpg goes according to ecu tune if you have a bad iac or w/e you're gas mileage will suck.

 

[jbramble2]

Go to an external wastegate off the O2 housing and never worry about boost creep again. This is the only way I was able to get rid of the creep with the EvoIII 16g.

 

[cjridert1]

O2 sensor is good?
Bad IAC, your idle is good (rather, decent) or no?
Vacuum leak should get you better mileage when cruising I would think; engine is pulling in some extra UNMETERED air. If its not huge, probably inappreciable differences.
As far as the creep goes, some people get away with porting/bigger flappers/O2 dumps, I didnt have much luck (but I didnt follow thru with all of this) and just switched to external. If you are having trouble after a bigger flapper and have a turbine housing that is ported/tapered/whatever, then maybe its time for external? Money well spent. Seems like people have luck with ebay wastegates, probably do this for some reasonable $$ (and a bit of work to get the runner tapped/flanged).

 

[Buurma]

O2 sensor is good?
Bad IAC, your idle is good (rather, decent) or no?
Vacuum leak should get you better mileage when cruising I would think; engine is pulling in some extra UNMETERED air. If its not huge, probably inappreciable differences.
As far as the creep goes, some people get away with porting/bigger flappers/O2 dumps, I didnt have much luck (but I didnt follow thru with all of this) and just switched to external. If you are having trouble after a bigger flapper and have a turbine housing that is ported/tapered/whatever, then maybe its time for external? Money well spent. Seems like people have luck with ebay wastegates, probably do this for some reasonable $$ (and a bit of work to get the runner tapped/flanged).

i have the vpc and gcc so no maf.. wideband always reads between 14.1 -15.5 when cruising, idle tho is from 1100-1500 back and fourth.. that ###### deserves its own thread tho. but as far as boost creep i turned my br mbc back up and she doesnt creep now



*edit*

Fixed the idle, and had a leaky coupler on the intercooler.

 

[nek]

I have a question I keep thinking about. If boost creep is mostly caused by nonrestrictive exhaust, then why do people port out the turbo to 02 housing? Shouldnt ALL the porting be focused on manifold to turbo? I would think porting the turbo to 02 would make things worse Oo.
And while were on the subject, how does air flow through our system. Is it, air intake, turbo, ic, tb, im, engine,turbo, 02, exhaust?

 

[JusMX141]

I have a question I keep thinking about. If boost creep is mostly caused by nonrestrictive exhaust, then why do people port out the turbo to 02 housing?

To attempt to make the wastegate passage in the o2 housing less restrictive in order to keep the boost level under control.

The Evo III turbine housing has a much larger outlet than a standard 16G 7cm housing, which I believe is the main reason the Evo III is the most prone to creep. The bigger and less-restricted your exhaust system is, the more issues with creep you're going to have.

A quick "test" is to unhook the actuator from the arm and take the car for a drive letting the flapper blow free. If your boost level climbs even with no tension at all on the flapper, you need to add some restriction to your exhaust or just crank up the boost and enjoy the ride.

 

[Buurma]

Scince i fixed my coupling my boost creeps all the way to 25+ i let off i dont want to destroy my 4g.
boost controller was returned to origional setting..

think i have a waste gate problem?

 

[nek]

A quick "test" is to unhook the actuator from the arm and take the car for a drive letting the flapper blow free. If your boost level climbs even with no tension at all on the flapper, you need to add some restriction to your exhaust or just crank up the boost and enjoy the ride.

Oh, so basically your saying that the reason we creep is because to much air is going straight through the 02 to the exhaust with out utilizing the flapper because air chooses least restrictive which happens to be the open exhaust instead of the flapper. since the flapper feels no pressure, the wastegate isnt being used, so the wastegate attempts to turn up the boost by itself to compinsate?
So when porting, you want to leave the lower 02housing alone but make the flapper open with as little restriction as possible. Am I going the right way with all of this?
Imma take this one step at a time and end it at that, if someone would just like to send me to the 411 of boost creep that would work also.

 

[jeffo]

turbo is EvoIII 16g ported i/o 34mm flapper

You are sure that the wastegate area of the turbine was heavily ported? My EVO3 used to creep to 25psi also, but FP's porting job fixed it. They took out a LOT of material, but they also shaped it so that the exhaust got aimed toward the wastegate hole, if I recall. I didn't get the 34mm flapper.

 

[Buurma]

You are sure that the wastegate area of the turbine was heavily ported? My EVO3 used to creep to 25psi also, but FP's porting job fixed it. They took out a LOT of material, but they also shaped it so that the exhaust got aimed toward the wastegate hole, if I recall. I didn't get the 34mm flapper.

I dont know i'm taking the builders word for it. she never used to creep until i fixed that boost leak.

this is ###### dumb or useless but i too the spring out of my "turbo xs" bov (i hate it) and she boosted and held at 18 all day, which is what the ecu is tuned for. so could my wastegate be off?

as quoted by builder,
"EvoIII 16g ported i/o 34mm flapper
ported evo exh mani
evo 02 housing ported to hell "

 

[Dizorganizer]

ok i have a problem also...

When im at WOT the boost will get to 10psi and hold.. then as soon as i hit about 4500-5500 it Shoots up to about 25? Vacuum leak? Im have an Evo 3 turbo with Evo 3 manifold. I checked my lines and all seem to be well. I just got done doing a head swap also. Anything anyone know of that will cause this to happen like this? I have turned down my boost to what i think is about 10psi(manual boost controller) it might be around 15 tho. Still the same problem just doesnt shoot up as high. Im wanting to get the car tune because of the new head. Its running rich at the moment. I want to get this fix before i get to the dyno. Or is this even a problem?