Welcome to the North American Subaru Impreza Owners Club Tuesday March 19, 2024
Home Forums Images WikiNASIOC Products Store Modifications Upgrade Garage
NASIOC
Go Back   NASIOC > NASIOC Technical > Engine Management & Tuning > AccessPort

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 07-26-2018, 07:31 PM   #1
wingman358
Scooby Newbie
 
Member#: 146760
Join Date: Apr 2007
Chapter/Region: RMIC
Location: Colorado
Vehicle:
2004 WRX Wagon
WRB

Default "Load Compensations (Manifold Pressure)" table is only 4 cells

I'm following some tuning guides (HolyCrapItsFast and Bad Noodle) which have instructed me to tune the Load Compensations. I'm using the MAF Scaling Tool which I think was created from Bad Noodle and Kodename47's spreadsheets.

I've nailed down injector latency, scale, and now MAF scale and the car's running great.

But my "Load Compensations (Manifold Pressure)" table is only 4 cells while the tuning guides show more like 100 cell tables... what's the deal? Is this a 16-bit / 32-bit issue?

Thanks.
* Registered users of the site do not see these ads.
wingman358 is offline   Reply With Quote
Sponsored Links
* Registered users of the site do not see these ads.
Old 07-26-2018, 08:06 PM   #2
Airboy
Scooby Specialist
 
Member#: 72829
Join Date: Oct 2004
Chapter/Region: W. Canada
Location: Calgary, Canada
Vehicle:
2006 WRX
2015 WRX

Default

Quote:
Originally Posted by wingman358 View Post
Is this a 16-bit / 32-bit issue?
Yes. 16bit ECU has that tiny table that can't really be used.
Airboy is offline   Reply With Quote
Old 07-26-2018, 08:49 PM   #3
wingman358
Scooby Newbie
 
Member#: 146760
Join Date: Apr 2007
Chapter/Region: RMIC
Location: Colorado
Vehicle:
2004 WRX Wagon
WRB

Default

Damn, so no load compensation tuning for me then. Is there a workaround?
wingman358 is offline   Reply With Quote
Old 07-27-2018, 12:11 AM   #4
Airboy
Scooby Specialist
 
Member#: 72829
Join Date: Oct 2004
Chapter/Region: W. Canada
Location: Calgary, Canada
Vehicle:
2006 WRX
2015 WRX

Default

Quote:
Originally Posted by wingman358 View Post
Damn, so no load compensation tuning for me then. Is there a workaround?
Switch to Speed Density mode and use the VE table.
Airboy is offline   Reply With Quote
Old 07-27-2018, 02:17 AM   #5
wingman358
Scooby Newbie
 
Member#: 146760
Join Date: Apr 2007
Chapter/Region: RMIC
Location: Colorado
Vehicle:
2004 WRX Wagon
WRB

Default

Quote:
Originally Posted by Airboy View Post
Switch to Speed Density mode and use the VE table.
Damn why's speed density so much better?
wingman358 is offline   Reply With Quote
Old 08-07-2018, 01:33 AM   #6
BMXspears
Scooby Newbie
 
Member#: 79339
Join Date: Jan 2005
Chapter/Region: RMIC
Location: Westminster, CO
Vehicle:
2002 EJ257 6spd WRX
Midnight Black

Default

The load compensations aren't there because the factory didn't think it was necessary. THOUSANDS of those cars get along just fine without them. So don't worry about it.
BMXspears is offline   Reply With Quote
Old 01-18-2019, 11:13 AM   #7
slow.wagon
Scooby Newbie
 
Member#: 484841
Join Date: Apr 2018
Chapter/Region: HIIC
Location: Hawaii
Vehicle:
2019 WRX STI

Default

Related question. Under what circumstances would one even bother modifying the "Load Compensation (Manifold Pressure)" tables? Is there a reason why they aren't just zeroed out on heavily modified cars? Just trying to understand the rational behind them.
slow.wagon is offline   Reply With Quote
Old 01-18-2019, 01:01 PM   #8
JSR84
Scooby Specialist
 
Member#: 469585
Join Date: Jun 2017
Chapter/Region: W. Canada
Vehicle:
2009 STi
White

Default

Quote:
Originally Posted by slow.wagon View Post
Related question. Under what circumstances would one even bother modifying the "Load Compensation (Manifold Pressure)" tables? Is there a reason why they aren't just zeroed out on heavily modified cars? Just trying to understand the rational behind them.
They're used to compensate for predictable fuel and air flow anomalies. An example of which is the GR stumble. The design of the GR fuel system creates a resonance in the fuel system resulting in flow flow instability at a particular RPM / MAP range causing a lean condition. The factory uses the load compensation table to help deal with this issue.

My Load Comp tables are zeroed out because I have gone to a larger fuel rail and a parallel style fuel line setup which has, according to my logging neutralized the the issue or at least to an imperceivable level.
JSR84 is offline   Reply With Quote
Old 01-18-2019, 09:53 PM   #9
slow.wagon
Scooby Newbie
 
Member#: 484841
Join Date: Apr 2018
Chapter/Region: HIIC
Location: Hawaii
Vehicle:
2019 WRX STI

Default

Quote:
Originally Posted by JSR84 View Post
They're used to compensate for predictable fuel and air flow anomalies. An example of which is the GR stumble. The design of the GR fuel system creates a resonance in the fuel system resulting in flow flow instability at a particular RPM / MAP range causing a lean condition. The factory uses the load compensation table to help deal with this issue.

My Load Comp tables are zeroed out because I have gone to a larger fuel rail and a parallel style fuel line setup which has, according to my logging neutralized the the issue or at least to an imperceivable level.
I am in the same boat, upgraded pump, rails, lines, fpr...the whole banana. I thought I had crawled ATR and fixed all the OEM junk compensation stuff but never encountered this table. Anyhow, my tune is stable but I am curious if I should bother zeroing this stuff out or just leave it alone. I don't like the idea of phantom compensations changing fueling in complex ways that aren't necessary. Would you recommend I also zero it out? Will I need to rescale my MAF for CL/OL ?
slow.wagon is offline   Reply With Quote
Old 01-19-2019, 02:17 AM   #10
JSR84
Scooby Specialist
 
Member#: 469585
Join Date: Jun 2017
Chapter/Region: W. Canada
Vehicle:
2009 STi
White

Default

Quote:
Originally Posted by slow.wagon View Post
I am in the same boat, upgraded pump, rails, lines, fpr...the whole banana. I thought I had crawled ATR and fixed all the OEM junk compensation stuff but never encountered this table. Anyhow, my tune is stable but I am curious if I should bother zeroing this stuff out or just leave it alone. I don't like the idea of phantom compensations changing fueling in complex ways that aren't necessary. Would you recommend I also zero it out? Will I need to rescale my MAF for CL/OL ?
It's really hard to say. I would zero the Load Comp, then watch for abnormal fuel fueling corrections. If you see some, note the airflow they're occuring at as well as the RPM and MAP. Then try and hit the airflow reading at a different RPM / MAP, if the correction is repeatable then chances are the MAF Calibration is out, if not its probably a resonance caused correction in that RPM / MAP region.

The Load Comp can mess with your MAF Calibration tuning process if you're not aware of it. Before I went to a parallel setup with larger rails, I zero my compensation but did my logging in MAP / RPM regions that I knew were accurate. Once I was happy with my MAF Calibration I would rework the Load Comp tables. It was a pain in the ass, but it gave me a good result. It's so much nicer now not having to worry about it.

Last edited by JSR84; 01-19-2019 at 02:25 AM.
JSR84 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 07:37 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.