Welcome to the North American Subaru Impreza Owners Club Sunday January 21, 2018
Home Forums 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.
* Registered users of the site do not see these ads. 
Reply
 
Thread Tools Display Modes
Old 12-26-2017, 10:39 PM   #1526
berserksti2
Scooby Newbie
 
Member#: 255226
Join Date: Aug 2010
Default

Quote:
Originally Posted by Tryptofan View Post
It sorta depends on your needs. If you're getting flow rates too high for the MAF sensor, then it's a no-brainer - MAF to control closed loop fueling and moderate load, and transition to speed density for high load when you're at the upper end of MAF voltage (> 4.5V or so).

You just have to make sure you've tuned all the VE tables properly - and all the environmental tables that apply to you. Intake temp in particular, and barometric pressure if you have big altitude changes for some reason.

One note for everyone using speed density in this thread that I forgot to mention that (at least I think) is really important: You should move your intake temp sensor to right before or somewhere after the throttle body (after the intercooler). SD works way better with the intake temp sensor in a place that doesn't heat soak and truly represents the temperature of air entering the cylinders. If your intercooler is huge and never heat-soaked, you could get away with having the intake temp sensor where the MAF is, but it makes things much easier to rewire the intake temp sensor to a post-intercooler position (still never sure why Subaru didn't do this from the factory - it even helps with environmental corrections when you run MAF).

Thanks for fielding PDXRealtor's questions Shinji (Xmastime activities intruding on car talk), that's exactly what he needs to do to get it set up correctly. Once you have your VE table set up, it'll work great.

One other thing that's really important when you tune your VE table though! Make sure you do all of your VE table tuning with as close to the same intake air temp as possible, and avoid any heat soak while you do it. If you try to do part of your VE tuning one day at 40f, and another day at 65f, you'll drive yourself insane since the adjustments to VE you have to make to hit the correct AFR will vary significantly. Either do it all at once, preferably around 65-80f (whatever temp your car spends most of the year at), or do part and wait until you have temps the same to finish it out. Less commonly an issue, but try to not change altitude significantly either (i.e., don't do all your tuning one day at 1000 feet, and another day at 1700 feet). As long as temp is the same, it will make the intake temp table and barometric pressure table compensations you have to make later on to keep running speed density much easier.
Thanks for all the info Tryptofan glad there are guys like you, ShinjiML, and a few others helping out here. I'm simply just maxing out the id on the big maf intake im running nearing the 5v mark and dont want a lean event if I max it out on really cold days and just want to transition to SD so I can turn up the boost and make more power without restriction. So i'm just going to use mafv to transition from maf to sd and just covering all the grounds prior to switching over and maybe run full time SD later down the line. I"m pretty comfortable with maf tuning just never really played around with SD. So just reading up mainly on the cobb sd guide and hopefully find more useful info to help supplement. As of right now I'm just trying to figure out the important tables aside from the ve map to touch upon and what increasing and decreasing table values do to the tune.
* Registered users of the site do not see these ads.
berserksti2 is offline   Reply With Quote
Sponsored Links
* Registered users of the site do not see these ads.
Old 12-27-2017, 12:09 AM   #1527
Tryptofan
Scooby Newbie
 
Member#: 216924
Join Date: Jul 2009
Chapter/Region: SWIC
Location: Phoenix, AZ
Vehicle:
2009 WRX STi
White

Default

Quote:
Originally Posted by ShinjiML View Post
Working on injector timing requires some basic understanding of the avcs system, because injector timing is changed in relations to avcs. Basically, with changes in avcs advance you will want to increase or decrease the injector timing values so that the injection point is proportional to the cam advanced or retard.
I read up a bit on it today. What I saw on other sites is that one strategy for tuning it involves setting a single target AFR value in open loop, and then making adjustments to make operation as rich as possible (signifying that the injector is pulsing at a time that gets as much fuel as possible into the cylinder and consuming oxygen to burn it, rather than blowing it through). That would supposedly maximize BSFC, and decrease pooling on the intake valves. Maybe you'd even get a cooler cylinder from this since more fuel droplets would be ending up getting carried into the cylinder, rather than evaporating off the valve? The last is just speculation on my part. Maybe someone else has a better idea for how to tune this most effectively (or whether tuning it is useful at all).

Quote:
Originally Posted by PDXrealtor
I find it odd I don't have the table ....
For some reason the 2015+ STI's are different. I have a 2009. Maybe just not revealed on yours yet.


Stock AVCS intake cam table and injection timing table attached below for anyone who's curious:



Now this is what doesn't make much sense to me:

The stock table retards injection completion timing (in degrees BTDC of the compression stroke) with increased loading at low RPM, and then phases that retard out at high RPM. This correlates with intake AVCS behavior. However, I don't understand why you'd want injection to complete later (retarded injection completion) when the intake valve is opening earlier. Unless this is maybe done because of a fuel blow-through issue - early injection + overlap between exhaust and intake resulting in fuel blown out the exhaust valve??

Edit: thinking about it some more, could it be at least in part because of how long the injection pulse is at high load? I'm calculating 0.055 milliseconds per degree of rotation at 3000 RPM, and the stock table has injection ending ~250 degrees BTDC (assuming load over .

For my injectors at least, if I have a latency of 0.81 ms at operating voltage, and let's say a pulse width of 8.2 ms at 2g/rev load, that's ~9 ms of injection time (164 degrees of rotation at 3k RPM) - in this imaginary example that means injection is actually starting (164+250) = 414 degrees before top dead center.

On stock injectors (more relevant to this stock table), maybe assume something more like 14 ms at 2g/rev, which would be 255 degrees until injection finishes, and injection starting 505 degrees BTDC(?).

Last edited by Tryptofan; 12-27-2017 at 01:25 AM.
Tryptofan is offline   Reply With Quote
Old 12-27-2017, 12:16 AM   #1528
Tryptofan
Scooby Newbie
 
Member#: 216924
Join Date: Jul 2009
Chapter/Region: SWIC
Location: Phoenix, AZ
Vehicle:
2009 WRX STi
White

Default

Quote:
Originally Posted by berserksti2 View Post
So i'm just going to use mafv to transition from maf to sd and just covering all the grounds prior to switching over and maybe run full time SD later down the line.
That sounds like a good plan to me - I'd just suggest you start the transition well before you max out the MAF sensor (start at 4.5V rather than at 4.9V). I'm not sure if it holds true for automotive mass flow sensors, but some (not all) gas mass flow sensors I've dealt with start having accuracy issues once you get to >95% of their full range.
Tryptofan is offline   Reply With Quote
Old 12-27-2017, 10:35 AM   #1529
86Dreams
Scooby Specialist
 
Member#: 385256
Join Date: Mar 2014
Chapter/Region: Tri-State
Location: Harriman NY
Vehicle:
02 WRX S204 swap

Default

Quote:
Originally Posted by Tryptofan View Post
Yeah, this is a little confusing now - maybe a really big transient leak. You've got a log (Log #4, romraiderlog_20171221_181019) that looks terrible - really lean.


While you have another that looks much better while you cruise (log #7 - romraiderlog_20171222_070832).


If you're changing injector scaling between these logs, then it would make more sense. If they're all run with the same scaling, then it looks like injectors aren't your problem and maybe you have a big leak somewhere. Maybe someone else can offer a suggestion.




It's still sort of a guess without a wideband. They're probably rich misfires since you haven't blown your motor up yet, but the front O2 sensor will read rich even if you're actually at 12.5:1 or something pretty lean due to the pre-turbine exhaust pressure.

I always look back to this post.
https://forums.nasioc.com/forums/sho...21&postcount=9
lean at mrp<0 and rich at mrp>0 indicates a leak POST throttle body.

are 02wagonowner are you able to pull the rom and post it?
86Dreams is offline   Reply With Quote
Old 12-27-2017, 01:46 PM   #1530
Tryptofan
Scooby Newbie
 
Member#: 216924
Join Date: Jul 2009
Chapter/Region: SWIC
Location: Phoenix, AZ
Vehicle:
2009 WRX STi
White

Default

Quote:
Originally Posted by 86Dreams View Post
I always look back to this post.
https://forums.nasioc.com/forums/sho...21&postcount=9
lean at mrp<0 and rich at mrp>0 indicates a leak POST throttle body.
Oooh, yeah, that looks like a very useful guide to diagnosing these issues.

That would make sense - sucking unmetered air in under vacuum leading to lean readings, and pushing out metered air under boost leading to rich readings and misfires.
Tryptofan is offline   Reply With Quote
Old 12-29-2017, 09:29 PM   #1531
ShinjiML
Scooby Specialist
 
Member#: 257231
Join Date: Sep 2010
Chapter/Region: Tri-State
Location: Hudson Valley, NY
Vehicle:
2011 STI ShinjiTuned
DGM

Default

Quote:
Originally Posted by Tryptofan View Post
I read up a bit on it today. What I saw on other sites is that one strategy for tuning it involves setting a single target AFR value in open loop, and then making adjustments to make operation as rich as possible (signifying that the injector is pulsing at a time that gets as much fuel as possible into the cylinder and consuming oxygen to burn it, rather than blowing it through). That would supposedly maximize BSFC, and decrease pooling on the intake valves. Maybe you'd even get a cooler cylinder from this since more fuel droplets would be ending up getting carried into the cylinder, rather than evaporating off the valve? The last is just speculation on my part. Maybe someone else has a better idea for how to tune this most effectively (or whether tuning it is useful at all).



For some reason the 2015+ STI's are different. I have a 2009. Maybe just not revealed on yours yet.


Stock AVCS intake cam table and injection timing table attached below for anyone who's curious:



Now this is what doesn't make much sense to me:

The stock table retards injection completion timing (in degrees BTDC of the compression stroke) with increased loading at low RPM, and then phases that retard out at high RPM. This correlates with intake AVCS behavior. However, I don't understand why you'd want injection to complete later (retarded injection completion) when the intake valve is opening earlier. Unless this is maybe done because of a fuel blow-through issue - early injection + overlap between exhaust and intake resulting in fuel blown out the exhaust valve??

Edit: thinking about it some more, could it be at least in part because of how long the injection pulse is at high load? I'm calculating 0.055 milliseconds per degree of rotation at 3000 RPM, and the stock table has injection ending ~250 degrees BTDC (assuming load over .

For my injectors at least, if I have a latency of 0.81 ms at operating voltage, and let's say a pulse width of 8.2 ms at 2g/rev load, that's ~9 ms of injection time (164 degrees of rotation at 3k RPM) - in this imaginary example that means injection is actually starting (164+250) = 414 degrees before top dead center.

On stock injectors (more relevant to this stock table), maybe assume something more like 14 ms at 2g/rev, which would be 255 degrees until injection finishes, and injection starting 505 degrees BTDC(?).
From what I understand, at low loads, it is beneficial to inject on a closed valve, allowing it to heat and vaporize, thus improving the fueling efficiency and improving MPGs, but at higher loads under boost, heat management now becomes a concern and fuel should be injected later, on an open valve, to prevent the fuel from heating up, but injecting too late would obviously be a bad thing. Then, as RPMs rise, the injection point must become earlier in order to keep up with increasing engine speed.

The stock injector timing looks pretty wonky for the cruising region, as it doesn't even match the stock AVCS settings and would not be beneficial to either performance or MPG.

Finding the best injector timing is a process in and of itself.
ShinjiML is offline   Reply With Quote
Old 01-01-2018, 01:00 AM   #1532
Tryptofan
Scooby Newbie
 
Member#: 216924
Join Date: Jul 2009
Chapter/Region: SWIC
Location: Phoenix, AZ
Vehicle:
2009 WRX STi
White

Default

Quote:
Originally Posted by ShinjiML View Post
The stock injector timing looks pretty wonky for the cruising region, as it doesn't even match the stock AVCS settings and would not be beneficial to either performance or MPG.
.
Well, that explains why it was so confusing to look at.

Is there any info on the gains or benefits you can get from tuning injector timing on a Subaru? Especially if the factory timing is pretty much useless.

Some random threads on the internet (guys on Motec forums, Megasquirt/Miata forums and LSx forums to name a few) say 5-10% torque gains can be had in the RPM ranges where the injector pulse width time is short enough to control where the fuel is ending up (<4k RPM). Not a ton, but it would be a fun learning experience, and maybe more can be had on Subarus if the factory timing is basically useless
Tryptofan is offline   Reply With Quote
Old 01-02-2018, 10:14 PM   #1533
ShinjiML
Scooby Specialist
 
Member#: 257231
Join Date: Sep 2010
Chapter/Region: Tri-State
Location: Hudson Valley, NY
Vehicle:
2011 STI ShinjiTuned
DGM

Default

Quote:
Originally Posted by Tryptofan View Post
Well, that explains why it was so confusing to look at.

Is there any info on the gains or benefits you can get from tuning injector timing on a Subaru? Especially if the factory timing is pretty much useless.

Some random threads on the internet (guys on Motec forums, Megasquirt/Miata forums and LSx forums to name a few) say 5-10% torque gains can be had in the RPM ranges where the injector pulse width time is short enough to control where the fuel is ending up (<4k RPM). Not a ton, but it would be a fun learning experience, and maybe more can be had on Subarus if the factory timing is basically useless
Yeah, any torque gain from injector timing is really something for the cruising region and the low range of the powerband.

From my own experimentation, I did notice a slight torque gain in the cruising region as I timed the injection earlier, in fact it even got rid of some cruise knock, but once I started the injection too early, the cruise knock actually came back along with losing the previous torque gain.

It's also not just about looking at the intake side. If you have a DAVCS car, you'll also have to look at the exhaust AVCS settings and take overlap into consideration. Injecting too early in a region with large overlap will just end up losing the benefits, as the fuel could just get blown out or pool, but injecting slightly before the exhaust closes can reap the benefits with little drawback.

So, it's really about finding the sweet spot.
ShinjiML is offline   Reply With Quote
Old 01-05-2018, 07:11 PM   #1534
Vtwrx04
Scooby Newbie
 
Member#: 97147
Join Date: Sep 2005
Chapter/Region: NESIC
Location: Vermont
Vehicle:
2012 wrx
gray

Default

Not sure if this link will work, so let me know.

https://docs.google.com/spreadsheets...#gid=730661407

oops wrong log look at this one

https://docs.google.com/spreadsheets...gid=1450486193

2012 wrx
Perrin TMIC
Perrin ELH
Invidia DP
SPT exhaust
Walbro 255

Just picked up a set of ID1000 injectors and a EBCS. Then a new tune.

Last edited by Vtwrx04; 01-05-2018 at 09:03 PM. Reason: correction
Vtwrx04 is offline   Reply With Quote
Old 01-05-2018, 08:34 PM   #1535
BehindTheLens
Scooby Newbie
 
Member#: 480179
Join Date: Jan 2018
Default 09 Outback XT - OTS Stage 1

2009 Outback 2.5XT MT

Hey all, I just added a Cobb AP and loaded the Stage 1 normal waste gate 91 octane map to it and I'm getting a quick boost spike to 18psi then it drops back down to around 15. Is this normal? Any help is greatly appreciated!

Link to WOT 3rd gear pull:
https://docs.google.com/spreadsheets...it?usp=sharing

EDIT: I also tried the low waste gate map with the same results.
BehindTheLens is offline   Reply With Quote
Old 01-06-2018, 12:49 AM   #1536
ShinjiML
Scooby Specialist
 
Member#: 257231
Join Date: Sep 2010
Chapter/Region: Tri-State
Location: Hudson Valley, NY
Vehicle:
2011 STI ShinjiTuned
DGM

Default

Quote:
Originally Posted by Vtwrx04 View Post
Not sure if this link will work, so let me know.

https://docs.google.com/spreadsheets...#gid=730661407

oops wrong log look at this one

https://docs.google.com/spreadsheets...gid=1450486193

2012 wrx
Perrin TMIC
Perrin ELH
Invidia DP
SPT exhaust
Walbro 255

Just picked up a set of ID1000 injectors and a EBCS. Then a new tune.
What octane fuel do you run?

What AFRs are you seeing?

Your DAM is at 0.69 with timing being added back in, which means you had some pretty bad knock previously and you are now recovering. Could have been a tank of bad gas.

Also your af learning is carrying pretty far into the wot pull. Either AF learning D was not disabled or the smoothing factor needs to be much larger.

Last edited by ShinjiML; 01-06-2018 at 12:58 AM.
ShinjiML is offline   Reply With Quote
Old 01-06-2018, 12:57 AM   #1537
ShinjiML
Scooby Specialist
 
Member#: 257231
Join Date: Sep 2010
Chapter/Region: Tri-State
Location: Hudson Valley, NY
Vehicle:
2011 STI ShinjiTuned
DGM

Default

Quote:
Originally Posted by BehindTheLens View Post
2009 Outback 2.5XT MT

Hey all, I just added a Cobb AP and loaded the Stage 1 normal waste gate 91 octane map to it and I'm getting a quick boost spike to 18psi then it drops back down to around 15. Is this normal? Any help is greatly appreciated!

Link to WOT 3rd gear pull:
https://docs.google.com/spreadsheets...it?usp=sharing

EDIT: I also tried the low waste gate map with the same results.
Are you running the ACN 91 map?

You have a good amount of knock in your log and the boost spike is not something that an OTS map can fix as you are already running the low wastegate map. Every car behaves slightly differently so the OTS map may not be suitable for your car. Getting a custom tune would probably be a good idea.
ShinjiML is offline   Reply With Quote
Old 01-06-2018, 09:35 AM   #1538
Vtwrx04
Scooby Newbie
 
Member#: 97147
Join Date: Sep 2005
Chapter/Region: NESIC
Location: Vermont
Vehicle:
2012 wrx
gray

Default

Thanks, always use 93 octane, usually Shell from the same place. Could have been bad gas, but seems unlikely. I just added the SPT exhaust, but I can't see why that would effect knock. Temperature was 40 when log was done, tomorrow predicting -15, so no logging for a while, lol��
Vtwrx04 is offline   Reply With Quote
Old 01-09-2018, 06:43 AM   #1539
PDXREALTOR
Scooby Newbie
 
Member#: 468393
Join Date: May 2017
Location: PDX OREGON
Vehicle:
2017 STI

Default

So - I think I have a good portion of the VE table pretty dialed in. I was hoping you guys could take a look and let me know what you think.

In the tables you will find 4-5 columns grouped together. RPM/MAP/Commanded Fuel/WBO2/Throttle Pos.

There is other data there but I grouped them together like that as I was working the VE table. Nice thing about Google sheets is they just stay that way.

I used my s# mode to start (mid boost on my car) and after that was looking good I moved over to s mode (max boost) where I made a couple minor adjustments.

Between my tuner who is tutoring me, and the suggestions from the people here I did this in about 3 hours. It takes me longer to mess around with the damn laptop and it's touch pad than it does to do a run, recognize, and make the changes. I'm going to get a little swinging table like the police. HA!

I was advised to remove some timing as the load may shift. I'm pretty sure it did as I'm seeing loads over 4.5 and I've never seen them that high before. I took out ~ 3* from the entire timing map (primary).

I can't quite wrap my head around an exact strategy to see just how much the load shifted and where. If I could get some advice on that I would be very thankful.

After I'm back to normal (timing dialed, VE finalized) I am going to have another session with my tuner and re-scale the load tables and take care of some other housekeeping stuff but first things first.

Here's the link to the folder with labeled files. Just start where you see 100% throttle pos. https://drive.google.com/drive/folde...uI?usp=sharing
PDXREALTOR is offline   Reply With Quote
Old 01-12-2018, 03:35 PM   #1540
mr.nicknasty8
Scooby Newbie
 
Member#: 244192
Join Date: Apr 2010
Chapter/Region: NESIC
Location: Vermont
Vehicle:
2006 WRX
ARC FMIC

Default

Quote:
Originally Posted by Vtwrx04 View Post
Thanks, always use 93 octane, usually Shell from the same place. Could have been bad gas, but seems unlikely. I just added the SPT exhaust, but I can't see why that would effect knock. Temperature was 40 when log was done, tomorrow predicting -15, so no logging for a while, lol��
Are you running all those parts on a cobb map? AVCS is really low
mr.nicknasty8 is offline   Reply With Quote
Old 01-16-2018, 04:12 PM   #1541
Tryptofan
Scooby Newbie
 
Member#: 216924
Join Date: Jul 2009
Chapter/Region: SWIC
Location: Phoenix, AZ
Vehicle:
2009 WRX STi
White

Default

Quote:
Originally Posted by PDXREALTOR View Post
So - I think I have a good portion of the VE table pretty dialed in. I was hoping you guys could take a look and let me know what you think.
https://drive.google.com/drive/folde...uI?usp=sharing
Been a while since I've had time to look in here, but that is looking way better than it was before. Your commanded fueling is much closer to what your sensor reads. It's great to hear that your tuner is helping you through the process, since he should be able to help you learn about the other aspects you need to learn about (how now that your loads have changed due to the fixed VE tables you'll need to readjust timing tables for example).
Tryptofan is offline   Reply With Quote
Old 01-16-2018, 05:32 PM   #1542
PDXREALTOR
Scooby Newbie
 
Member#: 468393
Join Date: May 2017
Location: PDX OREGON
Vehicle:
2017 STI

Default

I actually rescaled the timing and fuel tables. I took several columns from the original timing table and inserted them in the new table at the closest, resales loads, then interpolated. Have not had any issues.
PDXREALTOR is offline   Reply With Quote
Old 01-17-2018, 05:43 PM   #1543
wrxlaunch
Scooby Specialist
 
Member#: 181298
Join Date: May 2008
Chapter/Region: MAIC
Location: MAIC
Vehicle:
2015 FUQ21BottiTuned
Full Bolt on Flex Fuel

Default

https://datazap.me/u/aogayle1/log-15...=0&data=3-5-21


2015 WRX Stock intake, TBE, FMIC, TGV Deletes, EGR block off, DW655c, Flex Fuel.

What we go here? Still tuning
wrxlaunch 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 12:48 AM.


Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2018 Axivo Inc.
Copyright ©1999 - 2017, North American Subaru Impreza Owners Club, Inc.