Welcome to the North American Subaru Impreza Owners Club Thursday March 28, 2024
Home Forums Images WikiNASIOC Products Store Modifications Upgrade Garage
NASIOC
Go Back   NASIOC > NASIOC Technical > Factory 2.0L Turbo Powertrain (EJ Series Factory 2.0L Turbo)

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.







* As an Amazon Associate I earn from qualifying purchases. 
* Registered users of the site do not see these ads. 
Reply
 
Thread Tools Display Modes
Old 11-14-2012, 02:32 AM   #1
gwilliamson
Scooby Newbie
 
Member#: 298637
Join Date: Oct 2011
Chapter/Region: NESIC
Location: west haven CT
Vehicle:
2002 WRX
WHITE

Default Help 2002 Wrx Not Holding Boost?!

Hey guys so I just got my first turbo car (2002 wrx) While doing some decent pulls I noticed on my Turbo gauge it spikes then drops and spikes and drops. What do you think this could be mods are:

Cobb v.1 accessport stage 2 93 oct map
Kartboy s/s
Forge recirc valve
K&N panel filter
Catless up pipe (ebay brand)
Catless turbo back exhaust (ebay brand)
Oil/air separator
Cx racing alum. radiator
Jna turbo timer
Turbo blanket
Silicone turbo inlet
Front+rear strut tower braces
H-brace sub support

(i know most of them definitely have nothing to do with it just giving you the whole low down)

PLEASE HELP A NOOB THANKS
* Registered users of the site do not see these ads.
gwilliamson is offline   Reply With Quote
Sponsored Links
* Registered users of the site do not see these ads.
Old 11-14-2012, 02:55 AM   #2
TwoFifty
Scooby Newbie
 
Member#: 261764
Join Date: Oct 2010
Location: Kelowna BC
Vehicle:
2003 Impreza WRX
Blue

Default

Fluctuating boost is usually caused by a boost leak. Get the system pressure tested and fix your leaks then go from there.
TwoFifty is offline   Reply With Quote
Old 11-14-2012, 07:37 AM   #3
wrxlaunch
Scooby Specialist
 
Member#: 181298
Join Date: May 2008
Chapter/Region: MAIC
Location: MAIC
Vehicle:
2019 KUV 21
Crystal White

Default

Did it just start doing this with the temp change?
wrxlaunch is offline   Reply With Quote
Old 11-14-2012, 12:45 PM   #4
gwilliamson
Scooby Newbie
 
Member#: 298637
Join Date: Oct 2011
Chapter/Region: NESIC
Location: west haven CT
Vehicle:
2002 WRX
WHITE

Default

how would you recommend getting it pressure tested?
gwilliamson is offline   Reply With Quote
Old 11-16-2012, 01:52 AM   #5
gwilliamson
Scooby Newbie
 
Member#: 298637
Join Date: Oct 2011
Chapter/Region: NESIC
Location: west haven CT
Vehicle:
2002 WRX
WHITE

Default

At WOT in 5th gear especially I can feel the car loose boost over and over again as well as the gauge. The car holds perfect boost around 10 psi but once it hits 14/15 it will drop and go back and drop and go back. (Definitely not just a gauge problem) :/

ANY RECOMMENDATIONS?
gwilliamson is offline   Reply With Quote
Old 11-29-2012, 01:05 AM   #6
gwilliamson
Scooby Newbie
 
Member#: 298637
Join Date: Oct 2011
Chapter/Region: NESIC
Location: west haven CT
Vehicle:
2002 WRX
WHITE

Default

it hits anywhere between 15/20! BUMP AND DROPS
gwilliamson is offline   Reply With Quote
Old 11-29-2012, 09:59 AM   #7
jthatch12
Scooby Specialist
 
Member#: 321715
Join Date: May 2012
Chapter/Region: Tri-State
Location: Philly/SJ
Vehicle:
03 Big 16G WRX
PSM

Default

Quote:
Originally Posted by gwilliamson View Post
At WOT in 5th gear especially I can feel the car loose boost over and over again as well as the gauge. The car holds perfect boost around 10 psi but once it hits 14/15 it will drop and go back and drop and go back. (Definitely not just a gauge problem) :/

ANY RECOMMENDATIONS?
Dude, never go WOT in 5th gear! Most cars are tuned for 3rd, higher gears will cause you to overboost!
jthatch12 is offline   Reply With Quote
Old 11-29-2012, 11:26 AM   #8
bushflyr
Scooby Specialist
 
Member#: 89628
Join Date: Jun 2005
Location: Hawaii, Oahu
Vehicle:
'02 Wagon VF39'd
& Quick Racked

Default

Quote:
Originally Posted by jthatch12 View Post

Dude, never go WOT in 5th gear! Most cars are tuned for 3rd, higher gears will cause you to overboost!
What? Dude. You have no idea what you're talking about. Cars are turned in third because they won't make full body in second and they don't want the dyno going 130 mph in fourth. It has nothing to do with the fifth gear boost.

Any tune will hold proper boost in all gears.
bushflyr is offline   Reply With Quote
Old 11-29-2012, 12:22 PM   #9
ogboot
Scooby Specialist
 
Member#: 170906
Join Date: Feb 2008
Chapter/Region: RMIC
Vehicle:
2002 WRX
psm

Default

Quote:
Originally Posted by bushflyr View Post
What? Dude. You have no idea what you're talking about. Cars are turned in third because they won't make full body in second and they don't want the dyno going 130 mph in fourth. It has nothing to do with the fifth gear boost.

Any tune will hold proper boost in all gears.
Eh, you're both kind of right really. You touched on it a little bit; you don't need to go WOT in 5th unless you're at a pretty significant speed. From a common interstate speed, WOT is a bad idea in fifth. This is even more relevant to the 16bit ECU as it doesn't have per gear compensation.

And most cars are tuned for 3rd/4th whether it's a dyno tune or road tune. A car tuned for solid XXPSI in 3rd/4th will usually overshoot the boost target a bit in 5th on the stock boost control management.

@OP: Oscillating boost is an indication that you're overshooting your boost target. Talk to the original owner and find out who tuned it, or if it's even tuned at all. Then talk to the tuner. If it's not tuned, then yeah really talk to a tuner, and stop going WOT.

If the cars tuned, it may be because of the colder weather and you may just need to loosen the wastegate arm a little bit. Get more info on the car first though. Is it just the COBB ots map?

Here's a good rule of thumb. WOT on the interstate? drop it down to 4th at least. Not enough gear in 4th to downshift and go WOT? You're already going too fast! 4th gear tops out north of 100mph... Hell 3rd gear can get you to something like 80 if i'm not mistaken. Plus, EGTs start to be come questionable on most tunes after a hard 4th gear pull anyway.

Last edited by ogboot; 11-29-2012 at 02:30 PM.
ogboot is offline   Reply With Quote
Old 11-29-2012, 05:56 PM   #10
jthatch12
Scooby Specialist
 
Member#: 321715
Join Date: May 2012
Chapter/Region: Tri-State
Location: Philly/SJ
Vehicle:
03 Big 16G WRX
PSM

Default

Quote:
Originally Posted by ogboot View Post

Eh, you're both kind of right really. You touched on it a little bit; you don't need to go WOT in 5th unless you're at a pretty significant speed. From a common interstate speed, WOT is a bad idea in fifth. This is even more relevant to the 16bit ECU as it doesn't have per gear compensation.

And most cars are tuned for 3rd/4th whether it's a dyno tune or road tune. A car tuned for solid XXPSI in 3rd/4th will usually overshoot the boost target a bit in 5th on the stock boost control management.

@OP: Oscillating boost is an indication that you're overshooting your boost target. Talk to the original owner and find out who tuned it, or if it's even tuned at all. Then talk to the tuner. If it's not tuned, then yeah really talk to a tuner, and stop going WOT.

If the cars tuned, it may be because of the colder weather and you may just need to loosen the wastegate arm a little bit. Get more info on the car first though. Is it just the COBB ots map?

Here's a good rule of thumb. WOT on the interstate? drop it down to 4th at least. Not enough gear in 4th to downshift and go WOT? You're already going too fast! 4th gear tops out north of 100mph... Hell 3rd gear can get you to something like 80 if i'm not mistaken. Plus, EGTs start to be come questionable on most tunes after a hard 4th gear pull anyway.
I was gonna mention unless you're going 120+ but I figured most people arent that dumb on public roads.....

and 3rd gear tops out in the high 90s... I've done a lot of 3rd gear pulls for tuning
jthatch12 is offline   Reply With Quote
Old 11-30-2012, 01:17 PM   #11
gwilliamson
Scooby Newbie
 
Member#: 298637
Join Date: Oct 2011
Chapter/Region: NESIC
Location: west haven CT
Vehicle:
2002 WRX
WHITE

Default

thanks for the input! I am going to take it out tonight and go wot in 3rd and see if it over boosts.

It is tuned with a Cobb Accessport stage 2 93 oct

(1st generation accessport)
gwilliamson is offline   Reply With Quote
Old 11-30-2012, 01:22 PM   #12
car_freak85
Scooby Specialist
 
Member#: 13530
Join Date: Dec 2001
Chapter/Region: NWIC
Location: Cascadia
Vehicle:
EA63 , EA81T, EJ20G,
EJ205

Default

Quote:
Originally Posted by jthatch12 View Post
Dude, never go WOT in 5th gear! Most cars are tuned for 3rd, higher gears will cause you to overboost!
Wrong. Very ignorant comment with no support or evidence. What do you base this comment on? If your car can make boost in one gear, it should work in any gear. Period. If not, something is very wrong.

Quote:
Originally Posted by bushflyr
What? Dude. You have no idea what you're talking about. Cars are turned in third because they won't make full body in second and they don't want the dyno going 130 mph in fourth. It has nothing to do with the fifth gear boost.

Any tune will hold proper boost in all gears.
Most cars are tuned in 4th gear because that gear, in most cars, is a direct drive, meaning there is a 1:1 ratio, no torque multiplication. You could tune in first gear if you wanted, but it would be really quick and most likely, the 2600lb/ft of torque produced by 217lb/ft x 3.5xx first and a 3.54 final drive would spin the tires on the dyno rollers. That is the ONLY reason higher gears are used for dyno, the 1:1 gear ratio.

OP: I am having this same problem right now, but I'm waiting to have my car tuned. I have essentially a Vishnu stage zero kit installed.

Last edited by car_freak85; 11-30-2012 at 01:48 PM.
car_freak85 is offline   Reply With Quote
Old 11-30-2012, 04:41 PM   #13
ogboot
Scooby Specialist
 
Member#: 170906
Join Date: Feb 2008
Chapter/Region: RMIC
Vehicle:
2002 WRX
psm

Default

Quote:
Originally Posted by gwilliamson View Post
thanks for the input! I am going to take it out tonight and go wot in 3rd and see if it over boosts.

It is tuned with a Cobb Accessport stage 2 93 oct

(1st generation accessport)
Check with Cobb, I bet that map doesn't officially support the aftermarket turbo inlet either. Cobb's maps support turboback, intake or drop-in filter, and that's about it. When I put my inlet on I had to rescale my MAF because the car was running lean in boost and overboosting.

This map might be right up your alley, from their site: " Low Wastegate - For vehicles exceeding target boost". Protune would be better.

But really, continuing to go WOT isn't going to fix a thing. Quite the opposite.
Your mod list does not include a wideband O2 sensor, so you don't have a clue what your AFR is doing. Don't bother looking at the AP because it's just reading off of the stock sensor and it's likely not going to be correct.
ogboot is offline   Reply With Quote
Old 12-06-2012, 10:44 AM   #14
gwilliamson
Scooby Newbie
 
Member#: 298637
Join Date: Oct 2011
Chapter/Region: NESIC
Location: west haven CT
Vehicle:
2002 WRX
WHITE

Default

thanks man ill try that map!
gwilliamson is offline   Reply With Quote
Old 12-06-2012, 04:10 PM   #15
Tenament
Scooby Newbie
 
Member#: 246813
Join Date: May 2010
Chapter/Region: NWIC
Default

Do you have the factory boost solenoid installed still?

That's your reason why if so.
Tenament 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 06:34 AM.


Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2024 Axivo Inc.
Copyright ©1999 - 2019, North American Subaru Impreza Owners Club, Inc.

As an Amazon Associate I earn from qualifying purchases.

When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission
Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.