Welcome to the North American Subaru Impreza Owners Club Monday January 20, 2020
Home Forums Images WikiNASIOC Products Store Modifications Upgrade Garage
NASIOC
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.







* 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 12-10-2019, 09:05 AM   #1
Gerald81
Scooby Newbie
 
Member#: 34226
Join Date: Mar 2003
Default Huge increase in boost by 1% change in WGDC

Has anyone ever observed a phenomenon whereby you see a huge gain in max boost with a very small change in WGDC? For example on my car, at 87% WGDC, the max boost was only 14.5 PSI. Increasing WGDC by 1% to 88% would see max boost swing up to 28 PSI, whereas ideally the target was 25 PSI.

Could this be due to an actuator rod arm that has been adjusted too short?
* Registered users of the site do not see these ads.
Gerald81 is offline   Reply With Quote
Sponsored Links
* Registered users of the site do not see these ads.
Old 12-11-2019, 04:57 PM   #2
Joshfl420
Scooby Specialist
 
Member#: 353788
Join Date: Apr 2013
Chapter/Region: South East
Location: S Florida
Vehicle:
1997 Cherokee
Tuned by AlanSnackbar

Default

Cold where you are? have any logs to share? Might be creep but cant tell what care you have.
Joshfl420 is offline   Reply With Quote
Old 12-11-2019, 05:50 PM   #3
goldfingerfif
Scooby Newbie
 
Member#: 428541
Join Date: Aug 2015
Chapter/Region: MWSOC
Location: Tinley Park, IL
Vehicle:
2016 STi Base
Lapis Blue Pearl

Default

What year and model car and what are you using to tune?

You have several things that could effect it.
Turbo Dynamics Integral Negative
Turbo Dynamics Integral Positive
Turbo Dynamics Proportional
Boost Targets
Wastegate Duty (Low)
Wastegate Duty (High)
Wastegate Solenoid Frequency <- Important to note, if it is at 10Hz then you only have 10% jumps regardless of what you set so it might be giving 80% duty then 90% and a 10% jump still shouldnt make that much of a difference but you get the point.

If you could log
Target Boost
Boost (Relative Manifold Pressure)
Wastegate Duty
TD Integral
TD Proportional
TD Boost Error
Requested Torque
RPM
Intake Temp

That'd be a good starting point.
goldfingerfif is offline   Reply With Quote
Old 12-12-2019, 09:11 PM   #4
Gerald81
Scooby Newbie
 
Member#: 34226
Join Date: Mar 2003
Default

It's a 2007 STI but the engine is an EJ207. Turbo is a hybrid Blouch 1.5 XTR twin scroll.

Using ECUtek but boost is controlled by an Apexi AVCR so my tuner doesn't have any logs.

Initially I suspected the actuator arm had been adjusted too short, making the WGDC work like an on/off switch. But I am also wondering why the actuator requires such a high WGDC just to hit 1 bar before the switchover point. Actuator has been tested for leaks and no issue. Stock BOV tested ok as well.
Gerald81 is offline   Reply With Quote
Old 01-06-2020, 09:39 AM   #5
Gerald81
Scooby Newbie
 
Member#: 34226
Join Date: Mar 2003
Default

By way of an update, I tried a new aftermarket actuator from Forge Motorsport with the spring tuning kit.

We started out trying the softest first (green). At 0% WGDC the max boost was 9 PSI, 20% WGDC = 12 PSI, 40% WGDC = 15 PSI, 60% WGDC = 18 PSI. It seemed to max out at around 18 to 19 PSI.

We then decided to try the stiffest spring (red). From 0% up to 85% WGDC, the max boost remained at around 15 PSI (although it did spike a bit higher with more WGDC but always tapered back to 15 PSI). Going just 1% above 85% would see the boost shoot to 29 PSI.

Basically, with the soft spring, the boost was responsive to changes in WGDC but the peak boost was too low below our target. However, with the stiffest spring, it was capable of higher boost but it was uncontrollable (i.e. a huge increase within 1% change in WGDC).

Is this normal? What do you guys think could be the issue here?
Gerald81 is offline   Reply With Quote
Old 01-06-2020, 04:27 PM   #6
86Dreams
Scooby Specialist
 
Member#: 385256
Join Date: Mar 2014
Chapter/Region: Tri-State
Location: Harriman NY
Vehicle:
V7 S204
'19 Giulia Q4

Default

what kind of ebcs is it? Standard 2 port or after market 3 port... 4 port?
That asked, have you tried checking the duty cycle signal to the ebcs putting an osciloscope on it? Maybe youre running into an operating limit where 86% is being interpreted as 100% duty cycle. what is the base frequency of the apexi?
86Dreams is offline   Reply With Quote
Old 01-07-2020, 07:14 AM   #7
Gerald81
Scooby Newbie
 
Member#: 34226
Join Date: Mar 2003
Default

The EBCS I'm using is an Apexi AVCR with 3 port solenoid.

Would the duty cycle signal you describe above manifest itself differently when trying the softest spring (green) vs the hardest spring (red)? Let me check on the base frequency.

Today we tried the blue spring which was supposed to be sort of in between the red and green. It ended up behaving similar to the red spring, where the maximum boost held at 13 PSI from 0% WGDC until 85%. When WGDC is set to 90%, it would give 23 PSI. Again, unable to get anything in between. Between 86% to 89% the maximum boost will increase slightly from 13 PSI but it would always drop back down to 13 PSI at higher RPMs.
Gerald81 is offline   Reply With Quote
Old 01-07-2020, 11:21 AM   #8
86Dreams
Scooby Specialist
 
Member#: 385256
Join Date: Mar 2014
Chapter/Region: Tri-State
Location: Harriman NY
Vehicle:
V7 S204
'19 Giulia Q4

Default

Quote:
Originally Posted by Gerald81 View Post
The EBCS I'm using is an Apexi AVCR with 3 port solenoid.

Would the duty cycle signal you describe above manifest itself differently when trying the softest spring (green) vs the hardest spring (red)? Let me check on the base frequency.

Today we tried the blue spring which was supposed to be sort of in between the red and green. It ended up behaving similar to the red spring, where the maximum boost held at 13 PSI from 0% WGDC until 85%. When WGDC is set to 90%, it would give 23 PSI. Again, unable to get anything in between. Between 86% to 89% the maximum boost will increase slightly from 13 PSI but it would always drop back down to 13 PSI at higher RPMs.
It could. It sounds like either the ebcs or the apexi has a max operating limit of 86%DC above which it just acts like its on all the time.

Let me run through whats happeneing. sorry if you know any of this already I just want to make sure its all here.

to start the wastegate is held shut by the force of the spring. Whats pushing it open is exhaust pressure on the waste gate itself combined with boost pressure to the acuator. So for any spring there is a boost pressure where the spring compresses enough that the wastegate opens enough to divert enough exhaust to prevent the turbo from spinning faster.

In other words the the softness of the spring limits the amount of exhaust that can spin the turbo. To say that another way, a stiffer spring will force more air through the turbo (because it takes more pressure to depress it).

What an EBCS does is divert boost pressure away from the actuator, this means that the boost signal does not contribute as much to the waste gate opening allowing you to reach a higher boost.

The EBCS is an electronically controlled valve. it has an opening and closing rate.

The concept of duty cycle is a time period in which a switch is turned on. So a 50% duty cycle would be the switch on for half of its time period.

So to go back to your application. its possible that at 86% duty cycle the ebcs valve is 'floating'. closed preventing any boost signal from reaching the actuator.

youd have to check tho. How old is your ebcs, who made the ebcs, what is the output frequency of the apexi.
86Dreams 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 08:12 AM.


Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2020, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2020 Axivo Inc.
Copyright ©1999 - 2019, North American Subaru Impreza Owners Club, Inc.

As an Amazon Associate I earn from qualifying purchases.