Welcome to the North American Subaru Impreza Owners Club Saturday October 25, 2014
Home Forums WikiNASIOC Products Store Modifications Upgrade Garage
NASIOC
Here you can view your subscribed threads, work with private messages and edit your profile and preferences Home Registration is free! Visit the NASIOC Store NASIOC Rules Search Find other members Frequently Asked Questions Calendar Archive NASIOC Upgrade Garage Logout
Go Back   NASIOC > NASIOC General > Newbies & FAQs

Welcome to NASIOC - The world's largest online community for Subaru enthusiasts!
Welcome to the NASIOC.com Subaru forum.

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, free of charge, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, so please join our community today!

If you have any problems with the registration process or your account login, please contact us.
* Registered users of the site do not see these ads.
Reply
 
Thread Tools Display Modes
Old 05-21-2013, 01:01 AM   #1
Kalvus5
Scooby Newbie
 
Member#: 332400
Join Date: Sep 2012
Chapter/Region: BAIC
Vehicle:
2002 Subaru WRX
WRB

Default Questions about MBC already installed on car

Hey guys I have an 02 WRX that came with a PDE uppipe and a dual-stage TurboXS manual boost controller installed by the previous single-owner. I the maintenance documents it says he set it to 15 psi for the first level and then he hooked it up to a switch in the cabin and when flicked it goes to 17 psi. I've got a couple questions about the set-up though now that I've been researching it a bit more and any help would be great.

1) I've heard about "full boost partial throttle" and the problems that it can cause. I started to test it out on the street and I could never get it to go full boost with only partial throttle at all. It would always rise steadily with the amount of throttle that I gave the car, until it reached the 15 psi limit with the throttle all the way down. Also, I heard that these MBC's would overrride the controlled boost in gears 1-2 and it would hit its 15 psi limit instead of the 7-10 or whatever boost is limited to in those two gears. However, with mine it doesn't hit full boost in those two gears and hits 15/17 in gears 3,4,5. Does this mean he had it professionally tuned for the car? It doesn't seem to have any of the problems that other users have experienced with an MBC.

2) Also, I was thinking of going stage 1/2 in the future. I understand that I'd have to probably take off the MBC in order to get the cobb AP maps working right. I know stage 2 would definitely give me more power then what I have now but what about stage 1? Does anyone know the approximate HP I'm making with this setup and if stage 1 would be anymore? If it's not too much of a difference I'd probably just keep this setup for a while.

Some more info, the car has 171,000 miles and he had it installed pretty early in its life, around 50,000 miles. It seems then that its been pretty reliable and it's been set up correctly. I'm still a bit confused why he'd choose to do this and not go stage 1/2 but who knows..
* Registered users of the site do not see these ads.
Kalvus5 is offline   Reply With Quote
Old 05-21-2013, 03:09 AM   #2
Chicago AJ
Scooby Specialist
 
Member#: 353343
Join Date: Apr 2013
Chapter/Region: MWSOC
Location: Suburb of Chicago
Vehicle:
'13 WRX Sedan Stg 3
'13 Prius C 86mpg!

Default

Stock psi for your car is around 13.5. So 17 would more power than stage 1. Keep it how it is if it's lasted that long reliably.

Stage 2 would require a downpipe and a corresponding stage 2 tune.
Chicago AJ is offline   Reply With Quote
Old 05-21-2013, 06:51 AM   #3
HinshawWRX
Medium Frank
Moderator
 
Member#: 140114
Join Date: Feb 2007
Chapter/Region: MAIC
Location: Common Sense, VA
Vehicle:
2014 Porsche
GT3 (Currently on Fire)

Default

Find a stock electronic boost control solenoid and put it on there, ditch the MBC. At no point should you listen to Chicago AJ OR flip the switch for more boost. More boost without proper tuning= you gonna blow up.

I would find a good Subaru tuner/shop in your area and take it to them, tell them you want the car to be stock, then talk to them about a Stage 2 setup.

Did you have the car professionally inspected? Compression and leak down tests? Without those I wouldn't say the car is "pretty reliable."
HinshawWRX is offline   Reply With Quote
Old 05-21-2013, 07:48 AM   #4
jpatt006
Scooby Specialist
 
Member#: 289470
Join Date: Jul 2011
Chapter/Region: MAIC
Location: West Chester, PA
Vehicle:
2011 WRX stage 2+
DGM

Default

I would listen to Hinshaw... Any change in boost is also going to require tweaks in other areas...timing and AFR to name a couple. By just cranking up the boost you run the risk of running super lean...which could lead to BOOM. Take it to a tuner and have them look at it.

As far as thinking it will hit full boost at partial throttle or hit peak boost instantly in gears 1 and 2... Boost hast to build. Its not like you throw on an MBC and any time you hit the gas it will already be at peak. All the MBC will do is set a limit, the boost still has to build. Once it hits your peak (whether its 15 or 17 or whatever), the MBC will prevent it from raising any higher - assuming your wastegate can keep up...but thats a different discussion.

Cliff's Notes: Get a tune or lose the MBC.
jpatt006 is offline   Reply With Quote
Old 05-21-2013, 08:16 AM   #5
MD04WRX
Scooby Guru
 
Member#: 72891
Join Date: Oct 2004
Chapter/Region: MAIC
Location: In the blue & hating it!
Vehicle:
2014 Molten ST
98 2.5GT -2014 XV

Default

FYI - 02-03 WRX does not have the same problem as the 04 and up WRX with the open / closed loop issue. It is perfectly safe to run a MBC set to 15psi, and a up-pipe, and a down pipe. What you have is a basic 2 stage power level. I would only be concerned if you don't have a downpipe since it wasn't noted in the original post.
MD04WRX is offline   Reply With Quote
Old 05-21-2013, 10:12 AM   #6
the suicidal eggroll
Scooby Guru
 
Member#: 51961
Join Date: Jan 2004
Chapter/Region: RMIC
Location: Broomfield, CO
Vehicle:
2005 STi
2012 WRX

Default

Quote:
Originally Posted by jpatt006 View Post
Any change in boost is also going to require tweaks in other areas...timing and AFR to name a couple.
Not it won't, not unless you go outside the bounds of the table or into untuned cells.
the suicidal eggroll is offline   Reply With Quote
Old 05-21-2013, 11:18 AM   #7
Kalvus5
Scooby Newbie
 
Member#: 332400
Join Date: Sep 2012
Chapter/Region: BAIC
Vehicle:
2002 Subaru WRX
WRB

Default

Thanks for the replies. I believe the stock downpipe is on the car still since he never mentioned it in all the maintenance notes. Also, when I bought the car, everything about it said it was well-taken care of. It had been single-owned, the interior was flawless, and there was barely any bodywork damage to speak of except rock chips which made the car seem like it was well taken care of. I understand that 17 psi is right on the borderline for dangerous boost levels, but the mod was done pretty early and seems to work well, so although I have no way of telling I think he got a tune for it. And since he set it up for 15/17 I'm sure he flicked the switch every now and then and since it lasted for over 100.000 miles, I think it's safe. I'm just not sure what I want to do with it at the moment.
Kalvus5 is offline   Reply With Quote
Old 05-21-2013, 04:54 PM   #8
jpatt006
Scooby Specialist
 
Member#: 289470
Join Date: Jul 2011
Chapter/Region: MAIC
Location: West Chester, PA
Vehicle:
2011 WRX stage 2+
DGM

Default

Quote:
Originally Posted by the suicidal eggroll View Post

Not it won't, not unless you go outside the bounds of the table or into untuned cells.
I guess I was referring more to the OP's specific situation where an additional 3.5 psi above stock peak could cause a potential lean condition.
jpatt006 is offline   Reply With Quote
Old 05-22-2013, 01:37 PM   #9
prescottn6ft7
Scooby Specialist
 
Member#: 268918
Join Date: Jan 2011
Chapter/Region: MAIC
Location: Virginia Beach, Virginia
Vehicle:
2002 WRX Wagon
WRB

Default

Quote:
Originally Posted by jpatt006 View Post
an additional 3.5 psi above stock peak could cause a potential lean condition.
^This ... If you don't have a wideband installed I would consider getting one on the car.

Quote:
Originally Posted by MD04WRX View Post
FYI - 02-03 WRX does not have the same problem as the 04 and up WRX with the open / closed loop issue. It is perfectly safe to run a MBC set to 15psi, and a up-pipe, and a down pipe. What you have is a basic 2 stage power level. I would only be concerned if you don't have a downpipe since it wasn't noted in the original post.
Basically took the words out of my mouth. 02-03 have a lot less issues with MBC's but monitoring the AFR is crucial, and a downpipe would be recommended on the 17psi setting.


Quote:
Originally Posted by HinshawWRX View Post
Find a stock electronic boost control solenoid and put it on there, ditch the MBC. At no point should you listen to Chicago AJ OR flip the switch for more boost. More boost without proper tuning= you gonna blow up.

I would find a good Subaru tuner/shop in your area and take it to them, tell them you want the car to be stock, then talk to them about a Stage 2 setup.
This dude ChicagoAJ needs a timeout.

I would think 17psi is dangerously close to hitting fuel cut in a hard 3rd 4th gear pull... not something I would do often without a tune.

Returning to stock EBCS, putting a downpipe on, and flashing a stage II map with a tactrix cable would be much safer than how the car is setup now. Ideally if the funds are there, putting a stock EBCS on (or 3-port... I'll explain more in a sec), a downpipe, AEM (or other company) wideband gauge and an accessport then flashing a stage II OTS map, or going baller status and getting a protune with a 3 port EBCS would be what I'd do. Has the car lasted as long as it has.... yes, but will it last forever running 17psi and no protune .... magic 8-ball says "outlook hazy"
prescottn6ft7 is offline   Reply With Quote
Old 05-22-2013, 02:25 PM   #10
Kalvus5
Scooby Newbie
 
Member#: 332400
Join Date: Sep 2012
Chapter/Region: BAIC
Vehicle:
2002 Subaru WRX
WRB

Default

Quote:
Originally Posted by prescottn6ft7

^This ... If you don't have a wideband installed I would consider getting one on the car.

Basically took the words out of my mouth. 02-03 have a lot less issues with MBC's but monitoring the AFR is crucial, and a downpipe would be recommended on the 17psi setting.

This dude ChicagoAJ needs a timeout.

I would think 17psi is dangerously close to hitting fuel cut in a hard 3rd 4th gear pull... not something I would do often without a tune.

Returning to stock EBCS, putting a downpipe on, and flashing a stage II map with a tactrix cable would be much safer than how the car is setup now. Ideally if the funds are there, putting a stock EBCS on (or 3-port... I'll explain more in a sec), a downpipe, AEM (or other company) wideband gauge and an accessport then flashing a stage II OTS map, or going baller status and getting a protune with a 3 port EBCS would be what I'd do. Has the car lasted as long as it has.... yes, but will it last forever running 17psi and no protune .... magic 8-ball says "outlook hazy"
Yeah I was always iffy on the 17 psi level, seeing that it had been installed for almost 140,000 miles made me feel that it was safe even though it's definitely not. I'm actually only 16 and this if my first car and with the repairs I've had done for it already I'm a bit low on cash at the moment. With my job this summer I should have about 900-1200 left over after insurance costs to spend on the car and as we all know accessports and catted downpipes don't come cheap... I considered the tactrix cable but with no experience whatsoever I'm a bit over my head if I go that route and I'd need to research it a lot more before I do that.
Kalvus5 is offline   Reply With Quote
Old 05-22-2013, 02:36 PM   #11
HaubeRR
Scooby Specialist
 
Member#: 227975
Join Date: Oct 2009
Chapter/Region: MAIC
Location: Maryland
Vehicle:
2003 WGN 6MT 2.5
Hybrid Dom 1.5xtr WRB

Default

I have a stock boost control for sale and a prodrive ebs. Let me know if you are interested. I also have grimm speed mbc for sale if you want a nicer one.
HaubeRR is offline   Reply With Quote
Old 05-22-2013, 04:53 PM   #12
Kalvus5
Scooby Newbie
 
Member#: 332400
Join Date: Sep 2012
Chapter/Region: BAIC
Vehicle:
2002 Subaru WRX
WRB

Default

Quote:
Originally Posted by HaubeRR
I have a stock boost control for sale and a prodrive ebs. Let me know if you are interested. I also have grimm speed mbc for sale if you want a nicer one.
Alright thanks ill keep it in mind
Kalvus5 is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -4. The time now is 11:22 PM.


Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2014 Axivo Inc.
Copyright ©1999 - 2014, North American Subaru Impreza Owners Club, Inc.