Welcome to the North American Subaru Impreza Owners Club Friday July 21, 2017
Home Forums 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.
* Registered users of the site do not see these ads. 
Reply
 
Thread Tools Display Modes
Old 06-19-2017, 06:41 PM   #1
romanboy
Scooby Newbie
 
Member#: 356242
Join Date: May 2013
Location: Jacksonville, FL
Default How to properly tune knock out

This is not a how-to so sorry to anyone if the title is misleading.
Whenever someone posts that they are seeing FBK or FKL, someone will post to simply reset the ecu.

Tuners know that you don't want to do that. You want to leave the ecu as is for multiple reasons, a good reason being that you can datalog it and see what the engine is doing when you have knock.

So let me set this scenario up, say you are seeing -2.8 degrees of FKL from 2000-2500 rpm on a WOT pull.
Three things you could possibly do:
lower the target boost (adjust other boost tables as well)
respectably make it richer
pull the timing

Say you change the ignition table (open tgv) (pull a degree or two of timing) and don't reflash the ecu but make live changes.
When you do your next WOT datalog, would you assume to see no FKL given that you pulled the necessary amount of timing? Or would you have to reset the ecu learning parameters and drive for a while till it builds back up and then do a few WOT pulls until you are sure there is no knock in that range?
* Registered users of the site do not see these ads.
romanboy is offline   Reply With Quote
Sponsored Links
* Registered users of the site do not see these ads.
Old 06-21-2017, 06:51 AM   #2
romanboy
Scooby Newbie
 
Member#: 356242
Join Date: May 2013
Location: Jacksonville, FL
Default

bump!
romanboy is offline   Reply With Quote
Old 07-11-2017, 07:19 AM   #3
romanboy
Scooby Newbie
 
Member#: 356242
Join Date: May 2013
Location: Jacksonville, FL
Default

bump!
romanboy is offline   Reply With Quote
Old 07-11-2017, 10:15 AM   #4
86Dreams
Scooby Specialist
 
Member#: 385256
Join Date: Mar 2014
Chapter/Region: Tri-State
Location: Harriman NY
Vehicle:
What is this? An
injector laying contest?

Default

You would have to reset the ECU. The learned values are stored independantly of the primary ignition tables.

Keep in mind that, in a maf based system(you have a maf based system), ignition timing and open loop fueling are chosen from a table with cylinder load and rpm as the axes. So if you remove boost and the knock goes away it may be because there is less airflow and a different table value is being referenced. In that case you didnt actually fix the problem, you just went around it.
86Dreams is offline   Reply With Quote
Old 07-11-2017, 04:29 PM   #5
romanboy
Scooby Newbie
 
Member#: 356242
Join Date: May 2013
Location: Jacksonville, FL
Default

Quote:
Originally Posted by 86Dreams View Post
You would have to reset the ECU. The learned values are stored independantly of the primary ignition tables.

Keep in mind that, in a maf based system(you have a maf based system), ignition timing and open loop fueling are chosen from a table with cylinder load and rpm as the axes. So if you remove boost and the knock goes away it may be because there is less airflow and a different table value is being referenced. In that case you didnt actually fix the problem, you just went around it.
Thanks for the response, that's a good thing to think about!

For future reference, I found a few WOT cells that I had knock in. In the fine knock tables it had stored these values. I decided not to tune anything nor to reset the ecu. I kept driving the car doing WOT pulls (I am well aware of the implications) and eventually the value kept decreasing per the increments I set it at. However, I noticed something weird. For a few pulls when I entered those ranges, the fine knock value would start from 0 and increase to whatever the stored value was in .01 increments and then go back down. I've never seen this, normally it just shows the large number like -1.40 and then increases to a larger one or slowly decreases away. Found that interesting. The value eventually reached zero and I no longer have fine knock in those cells.
romanboy is offline   Reply With Quote
Old 07-12-2017, 03:08 PM   #6
86Dreams
Scooby Specialist
 
Member#: 385256
Join Date: Mar 2014
Chapter/Region: Tri-State
Location: Harriman NY
Vehicle:
What is this? An
injector laying contest?

Default

it may be an adjacent cell with a lower number stored in it. and you are just observing cell progression.

The ECU will constantly test timing so if you adjust timing and did not reset, it will eventually un-learn the knock, if that was the problem.
86Dreams is offline   Reply With Quote
Old 07-13-2017, 06:27 AM   #7
romanboy
Scooby Newbie
 
Member#: 356242
Join Date: May 2013
Location: Jacksonville, FL
Default

Quote:
Originally Posted by 86Dreams View Post
it may be an adjacent cell with a lower number stored in it. and you are just observing cell progression.

The ECU will constantly test timing so if you adjust timing and did not reset, it will eventually un-learn the knock, if that was the problem.
I was thinking something around those lines. I never reset the ecu or adjusted timing. So the ECU over just quite a full WOT pulls was able to put the timing back in.
romanboy 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 07:57 PM.


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