Welcome to the North American Subaru Impreza Owners Club Sunday April 20, 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 Technical > Engine Management & Tuning

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 01-10-2006, 11:46 AM   #1
Kha0S
Scooby Guru
 
Member#: 8808
Join Date: Jul 2001
Chapter/Region: NESIC
Location: Grantham, NH
Vehicle:
2011 WRX (DGM 5D)
2002 WRX/2003 SVTF

Question Tuners -- boost oscillation fixes?

So, ever since I put in my downpipe foreverago, when the weather gets cold, I get nasty boost oscillations on throttle application, particularly in high gear (ie, 5th on the highway).

Now, there's all sorts of physical solutions that people talk about (wastegate actuator arm adjustment, replacement/modified restrictors, etc.), but the obvious solution is to adjust the maximum wastegate duty and turbo dynamics maps to compensate for the particular car.

What's your normal approach to fixing boost oscillation? What numbers do you usually end up using in the turbo dynamics maps?

Thanks!

/Andrew
* Registered users of the site do not see these ads.
Kha0S is offline   Reply With Quote
Old 01-10-2006, 12:12 PM   #2
mrbell
Scooby Specialist
 
Member#: 1871
Join Date: Jul 2000
Location: Salt Lake City, UT
Vehicle:
2000 Impreza 2.5RS
Blue Ridge Pearl

Default

The problem is, if your hardware isn't up to spec(wastegate actuator arm out of spec, which happens alot from the factory), it's impossible to come up w/ a generic baseline. You'll have to custom tune your maps to compensate. You could also run into limitations on how much the ECU can compensate for poor hardware setup.
It's possible that your wastegate is in spec, but that is the most common cause of this, and it is why so many people recommend a physical, rather than software, adjustment.
mrbell is offline   Reply With Quote
Old 01-10-2006, 12:20 PM   #3
Kha0S
Scooby Guru
 
Member#: 8808
Join Date: Jul 2001
Chapter/Region: NESIC
Location: Grantham, NH
Vehicle:
2011 WRX (DGM 5D)
2002 WRX/2003 SVTF

Default

Quote:
Originally Posted by mrbell
The problem is, if your hardware isn't up to spec(wastegate actuator arm out of spec, which happens alot from the factory), it's impossible to come up w/ a generic baseline. You'll have to custom tune your maps to compensate. You could also run into limitations on how much the ECU can compensate for poor hardware setup.
It's possible that your wastegate is in spec, but that is the most common cause of this, and it is why so many people recommend a physical, rather than software, adjustment.
I have no problem custom tuning my maps, and I've managed to tune out some of the problem, but can't seem to get it to go away entirely. It's hard to tell when the ECU uses the continuous vs. burst dynamics maps, so I can't seem to get the problem to go away completely.

I've managed to minimize the extent of the oscillation (down to about +- 1psi), but it doesn't damp out entirely.
Kha0S is offline   Reply With Quote
Old 01-10-2006, 12:51 PM   #4
mrbell
Scooby Specialist
 
Member#: 1871
Join Date: Jul 2000
Location: Salt Lake City, UT
Vehicle:
2000 Impreza 2.5RS
Blue Ridge Pearl

Default

That sounds alot like your Wastegate duty cycles are conflicting with your boost targets. Which is exactly where setting the actuator arm into proper adjustment can help. Your computer may be attempting to do something that the hardware is incapable of supporting properly.
mrbell is offline   Reply With Quote
Old 01-11-2006, 07:36 AM   #5
WolfPlayer
Scooby Specialist
 
Member#: 65054
Join Date: Jun 2004
Chapter/Region: MAIC
Location: Frederick, MD
Vehicle:
2005 STI (CGM)
Descooped / Dewinged

Default

If things are within spec mechanically AND with boost and wastegate duty cycoles then most often this turns out to be a Turbo Dynamics Map issue. Check mechanical things, check boost as related to WGDC ... then finally start adjusting the dynamics to get rid of the oscillations.

t
WolfPlayer 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

Similar Threads
Thread Thread Starter Forum Replies Last Post
Boost oscillation problem twizzstyle Factory 2.0L Turbo Powertrain 64 05-20-2013 03:09 AM
Vishnu Stg. II Boost Oscillation *HELP* amazonparrot Commercial ECU Reflashes 39 09-25-2007 06:31 PM
WOT boost oscillation at around 85 mph, please help impactblue Factory 2.0L Turbo Powertrain 14 01-07-2007 09:33 AM
03 WRX with boost oscillating problem X_Driver Factory 2.0L Turbo Powertrain 4 01-01-2007 10:55 AM
boost oscillation problem bugeyes Factory 2.0L Turbo Powertrain 9 04-23-2006 10:16 AM


All times are GMT -4. The time now is 08:37 AM.


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.