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Old 01-23-2008, 12:01 PM   #1
Jason-STI
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Default Knock Control and Tuning Tips

Been logging last couple of days and noticed a consistent trend and a few questions.

Details:
Stock JDM 2005 STi
Running on 97 ron unleaded fuel with outside temp at 30-33C.
Stock Boost of 1.4bar
Everything else stock

Observations:
There seems to be some 'negative' values showing up on my 'Fine Learning Knock Correction' logged parameter. It ranges from (-2.11) as early as 2342 rpm/ 1.49 load points on two consecutive occassions before registering '0' again up to about 3000 rpm before registering again at (-2.11) and immediately hitting (-6.33) consecutively for 7 counts from 3200 rpm/2.10 load points onwards. IAM started at 16 and eventually ended on at 2 at 5000 rpm. Knock Correction did not register any negative values though.

Question1:
How do i tune to resolve this? Reduce 'Timing Advance' on those affected points or reduce 'Base timing' or reduce both and by how much? And do i also need to tune other maps? i.e.Fine Correction, Feedback Correction, Rough Correction, etc

Question2:
In terms of tuning order, do you guys tune Fuel followed by Timing or the other way round? (If target boost and WGDC is kept at factory). And if intend to increase boost, do i tune boost first before fuel and timing?

Question3:
Which is a better tuning method A) Higher Boost/Lower Timing/Leaner Fuel or B)Lower Boost/Higher Timing/Richer Fuel?

Question 4:
Which are the specific maps on ECUflash which co-relates to the specific logged parameters on Enginuity i.e. Tune 'Timing Advance' and read 'Ignition Timing Advance' on Log, Tune 'Primary Open Loop Fueling' on ECUflash and read WBO2. I'm confused with the multiple 'fuel' and 'timing' tables from my rom. Is there a guide somewhere?

Thanks.
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Old 01-23-2008, 12:29 PM   #2
Zumble
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Knock correction didn't register any neg numbers because the timing has been pulled already before the KC even got added. So if you're calling for 25 degrees of total timing.. 18 base and 7 of advance. Normally you will see a KC of 7 if all is well and taking full timing. Lets say you're knocking and the ECU pulls 8 degrees of timing consistently. It will add -8 to your fine learning table. Now your total timing looks like this.. 18-8+7=17. So now your total timing is at 17 and staying there and our KC will register a full 7. At one point it was at -1 resulting in the -8 in the fine learning table. Being that your IAM dropped probably means you're knocking pretty badly though.

1. Reduce the base timing. Review your logs and see where the timing is being pulled and how much. Pull it from the base.
2. Tune fuel before timing.
3. If you have a efficient setup thats properly setup, I subscribe to A. If you don't have a optimal setup go with B.
4. I'll let someone who tunes with enginuity often answer that.

Last edited by Zumble; 01-23-2008 at 12:45 PM.
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Old 01-23-2008, 01:02 PM   #3
Tea cups
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Quote:
Originally Posted by Zumble View Post
Knock correction didn't register any neg numbers because the timing has been pulled already before the KC even got added. So if you're calling for 25 degrees of total timing.. 18 base and 7 of advance. Normally you will see a KC of 7 if all is well and taking full timing. Lets say you're knocking and the ECU pulls 8 degrees of timing consistently. It will add -8 to your fine learning table. Now your total timing looks like this.. 18-8+7=17. So now your total timing is at 17 and staying there and our KC will register a full 7. At one point it was at -1 resulting in the -8 in the fine learning table. Being that your IAM dropped probably means you're knocking pretty badly though.
This is false. KC = (advance*iam/16) + feedback knock correction + fine learning knock correction. So, for example, say advance = 7, IAM = 16, FBKC = 0, and FLKC = -8, then KC would be -1 (7 + 0 + (-8)). KC is the actual correction with advance (due to knock) that is finally added to base timing, so it will already reflect IAM/FBKC/FLKC. There is no other knock related timing compensation.

Also, the ECU does not make changes to the fine learning table based on patterns of feedback correction.
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Old 01-23-2008, 01:35 PM   #4
Zumble
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Is this the same on 32bit ECUs? I'm pretty sure on my own car I've seen my car give full advance of 9 thorugh the map but I find that there is -2 in the fine learned correction table (cobb calls this the knock correction table).

Quote:
Originally Posted by Tea cups View Post
This is false. KC = (advance*iam/16) + feedback knock correction + fine learning knock correction. So, for example, say advance = 7, IAM = 16, FBKC = 0, and FLKC = -8, then KC would be -1 (7 + 0 + (-8)). KC is the actual correction with advance (due to knock) that is finally added to base timing, so it will already reflect IAM/FBKC/FLKC. There is no other knock related timing compensation.

Also, the ECU does not make changes to the fine learning table based on patterns of feedback correction.
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Old 01-23-2008, 01:46 PM   #5
Tea cups
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Quote:
Originally Posted by Zumble View Post
Is this the same on 32bit ECUs? I'm pretty sure on my own car I've seen my car give full advance of 9 thorugh the map but I find that there is -2 in the fine learned correction table (cobb calls this the knock correction table).
Yes, it is the same for the 32-bit ECUs. If you are viewing Cobb's "knock correction table" (i.e. fine learning table) after the run, then obviously the cell could have changed after you closed your log and continued driving OR you are looking at the wrong cell -> I'm not sure how Cobb displays the load/rpm ranges and whether it is clear that these are ranges for each cell beginning with 0-1st load threshold (ex. 0-1.0 g/rev) and 0-1st rpm threshold (ex. 0-1800), with the last threshold including all values equal to or greater than that threshold (ex. 6500+ rpm). Another possibility is that the way logging works with factory ECU, groups of parameters on the same line in your logs can be polled at slightly different times.
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Old 01-23-2008, 02:17 PM   #6
Zumble
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Actually I view my KC in real time via my ScanMaster3. I didn't actually log the pull. I did a pull in 4th which puts me in the 3.x range and I had a -2 between 4000-4700 but during the pull I saw 9s the whole way down. I assumed this was because the 2 degrees were taken off my base timing already. I figured I only see the KC take a hit when the feedback correction is active. As in it's pulling 2 degrees right when I was doing that pull.

The scaling is controlled by the base map. It uses the fine learning boundary values and makes a table.

Last edited by Zumble; 01-23-2008 at 02:22 PM.
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Old 01-23-2008, 02:43 PM   #7
Tea cups
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There is no way FLKC and FBKC are not reflected in KC and this has been proven not only to myself in reverse engineering these ROMs, but also in practice among many others where it has been shown log after log after log.

Watching KC real-time, while guessing load during a run, I think you would agree is not the most reliable method for determining this either way. Did you check Cobb's "knock correction table" before and after the run? Try using enginuity's logger with the latest logger defs and you can actually log the 3 individual elements of KC.
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Old 01-23-2008, 03:12 PM   #8
Zumble
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Enginuity logger doesn't seem to like my ST flashed ECU.. =(

I assumed the load was correct because boost was correct but none of this was logged. I just play with the stuff, you guys make the tools.

Quote:
Originally Posted by Tea cups View Post
There is no way FLKC and FBKC are not reflected in KC and this has been proven not only to myself in reverse engineering these ROMs, but also in practice among many others where it has been shown log after log after log.

Watching KC real-time, while guessing load during a run, I think you would agree is not the most reliable method for determining this either way. Did you check Cobb's "knock correction table" before and after the run? Try using enginuity's logger with the latest logger defs and you can actually log the 3 individual elements of KC.
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Old 01-23-2008, 03:19 PM   #9
Tea cups
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Quote:
Originally Posted by Zumble View Post
Enginuity logger doesn't seem to like my ST flashed ECU.. =(
I know of at least several guys who tune with ST and log with Enginuity no problem. What issue are you having?
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Old 01-23-2008, 03:22 PM   #10
Zumble
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Don't want to steer the topic off course but this is the problem:

http://forums.nasioc.com/forums/show....php?t=1431104

Quote:
Originally Posted by Tea cups View Post
I know of at least several guys who tune with ST and log with Enginuity no problem. What issue are you having?
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Old 01-23-2008, 05:53 PM   #11
mickeyd2005
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1. The problem is that FLKC just tells you that somewhere in region xxx there is a problem. You have to log a lot and do an analysis of your logs to determine when FLKC is changing. I wrote a spreadsheet to do this analysis. It's in ride5000's server. I'm going to redo it because I didn't realize that Tea Cups (merchgod) had added an FLKC offset parameter which will make it much more accurate.
2. I tune fuel (conservative), boost and timing concurrently, fuel again, timing again, and then AVCS.
3. I prefer boost for making power. However, not too much boost. Plot Load (g/rev) versus MRP (psi) to see where you are becoming inefficient.
4. You really need to read Tea Cups (merchgod) knock control strategy on enginuity.org as well as his boost control writeup. Unfortunately, that website is down. Maybe, it'll be copied somewhere else soon.
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Old 01-24-2008, 01:36 PM   #12
Jason-STI
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Thanks guys for the feedback.

I have done about 5-6 logs today and yesterday.

Essentially IAM has flip flopped from the various logs. From the first log it ended at 2 @ 5000rpm/2.6grev. The second log started and ended with 8 @ approx same rpm/load points. From there, log 3 onwards registered and maintained IAM at 9 so far.

As for FLKC with IAM at 8-9, i am registering 0.35 (circa 4900rpm/2.58grev) on two consecutive points before getting -1.76 (circa 5000rpm/2.6grev) and -3.86 (circa 5300rpm/2.62grev). All WOT pulls on 4th and this is consistent readings from the last 3 logs. Am afraid to pull beyond 5500 rpm, looking at the situation. Suspect there will be more 'negative' value readings on FLKC up the rpm/load range.

So essentially on Q1 from my first post. It seems that i need to correct the negative values from FLKC from the specific affected load/rpm points and that should eventually bring IAM back up to 16, right?

And to do so i need to reference those affected load/rpm points from my logs to similar load/rpm points on my timing maps and adjust accordingly.

Question, do i:

A) reduce Base timing, or
B) reduce Timing Advance (Max), or
C) reduce both, or
D) tweak other table/maps as well

and in doing one of the above, do i also need to adjust boost or fuel maps concurently to solve this 'knock" issue?

Sorry but am new to this. Have read teacup's/merchgod's "knock control strategy" numerous times and took me awhile to sink in. And only now am slowly making sense as to how Fine and Rough correction works but am still not able to understand how do you tune timing to overcome knock and conversely, tune for Maximum Best Timing.

Teacups could you help here. Thanks and much appreciated.

Last edited by Jason-STI; 01-24-2008 at 02:09 PM.
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Old 01-24-2008, 02:33 PM   #13
Tea cups
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With the wide swings in the IAM with your car and with you being 100% stock with no changes to the factory map, you need to first determine why the ECU is seeing a large number of knock events. This shouldn't be the case if you are using the correct octane for the map (not sure what a JDM STi requires - do you live in Japan or did you have it imported to the UK or something?). It could be any (or some combination of the following):
1. mechanical/maintenance issue
2. incorrect octane for map and/or crappy gas quality
3. false knock due to rattling heatshield, etc.
4. motor is on its way out.
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Old 01-24-2008, 06:36 PM   #14
Jon [in CT]
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Quote:
Originally Posted by Jason-STI View Post
Details:
Stock JDM 2005 STi
Running on 97 ron unleaded fuel with outside temp at 30-33C.
Stock Boost of 1.4bar
Everything else stock
I had no idea that the factory tune for the JDM STI was set to achieve 1.4 bar (20.3 PSI) boost.
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Old 01-25-2008, 01:22 AM   #15
mickeyd2005
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Interesting. This rom has a target boost of 18.56 psi (1.26 bar).

http://forums.openecu.org/viewtopic.php?t=3078

Is it an S203? Can you post the stock rom to openecu.org?
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Old 01-25-2008, 11:37 PM   #16
Jason-STI
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Yup its an S203. Sorry didn't mentioned in my first post.

I suspect its the 'crappy fuel' issue cause we only have 97 ron unleaded fuel here (South East Asia). I believe in Japan its higher a grade and quality of fuel that the car was meant to run on.Probably 100 ron? So ya i suspect its the fuel quality issue that is probably causing the knock. What can i do to resolve this? Do i start with timing and see how it goes? And if so, do i only reduce base timing in those knock prone spots or advance timing? or do i reduce both (base + advance) at the same time and by how much?

I've been logging 1.35 - 1.38 peak boost (manifold rel. pressure corrected).

IAM has settled more or less at 9 for the last two logs.
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Old 01-26-2008, 12:17 AM   #17
mickeyd2005
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Can you share your stock rom? That would help. You can email it to me at my screen name at yahoo dot com or you can post it on openecu.org.

I only have a 2004 S203 rom and the boost target is different.
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Old 01-26-2008, 02:03 AM   #18
Jason-STI
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I've just gone on and registered at openecu.org. Will post my rom up once i have access from the administrator. Might as well share it with the rest of the community.

Wish i could post my log here for review.

Anyways, i suspect its the fuel quality issue that is probably causing the knock. What can i do to rectify this immediately?

Just need to know also whether when we tune timing tuning - do we work only on Base map or Advance map, or do we work on both at the same time? whether to increase or reduce.
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Old 01-26-2008, 02:07 AM   #19
mickeyd2005
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I would really like to see the fuel table first. If it is too lean for your fuel type, you might want to richen up some areas.

Then I would reset the ecu and log rpm, load, AFR #1, feedback correction, fine learning knock correction, IAM, and manifold relative pressure corrected. I would log 100% of the driving for about a total of 2 hours regular driving style. It'll be a big file, but you'll be able to identify the spots where it is knocking still and then adjust base timing as necessary.

Just for curiosity, I'm really interested in seeing the stock rom...
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Old 01-26-2008, 09:43 AM   #20
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Since it is octane issue, I would take the advance map and cut the values in half and start there. The JDM maps have quite a bit of timing.
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Old 01-27-2008, 01:42 AM   #21
Jason-STI
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Thanks tea cups for the direct answer i was looking for!

do i cut half across the entire advance map or just knock prone rpm/load points? would this necessarily bring IAM back up to 16 as well?

btw, when reflashing, do you guys also reset the ecu using ecuexplorer?

thanks and much appreciated.
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Old 01-27-2008, 09:52 AM   #22
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Quote:
Originally Posted by Jason-STI View Post
Thanks tea cups for the direct answer i was looking for!

do i cut half across the entire advance map or just knock prone rpm/load points? would this necessarily bring IAM back up to 16 as well?

btw, when reflashing, do you guys also reset the ecu using ecuexplorer?

thanks and much appreciated.
The idea behind Subaru's base map + advance map is that the base map timing is the maximum amount of timing that can be run, without knock, for the lowest octane gas the vehicle will encounter. The advance map is the additional timing for higher octane fuel. It is not perfect, but for our gas in the U.S. I think it would work as follows:

87 octane = Base timing + (advance map * 0) (i.e. IAM = 0)
89 octane = Base timing + (advance map * .5) (i.e. IAM = 8)
93 octane = Base timing + (advance map) (i.e. IAM = 16)

That is, the motor won't self-destruct if someone temporarily/accidently fills up a tank with 87. I'm not familiar with the octanes in other countries, but if you can figure out what the required premium is in Japan as compared to your premium, you might be able figure out a starting point for your advance map. Then, if, IAM remains solid at 16 and everything looks good you can start adding timing back in for performance.
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Old 01-27-2008, 11:16 AM   #23
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Fantastic! Finally, i understand how base and advance works with regards to octane!

Now it makes sense and i get why u suggested to cut timing advance by half and work from there. And if i half the advance map and IAM climbs back to 16 - i have a good starting point to move up from there. Got it!

Just wondering - doesn't that mean it would be an average tune across the entire map and not optimized tune for specific to rpm/load points that i would usually hit?

When i reflash, should i also reset the ecu with ecuexplorer or it does not matter? Tks.
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Old 01-27-2008, 11:34 AM   #24
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Quote:
Originally Posted by Jason-STI View Post
Just wondering - doesn't that mean it would be an average tune across the entire map and not optimized tune for specific to rpm/load points that i would usually hit?
No, it would not be optimized. But, it appears that the JDM factory tune is much too aggressive for your fuel octane. The way it is, with your IAM all over the place, it would be much easier/safer to tune from a conservative starting point than where it is now.

Quote:
When i reflash, should i also reset the ecu with ecuexplorer or it does not matter? Tks.
Not necessary. The ecu is reset during flashing for almost all ECUs.
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Old 01-27-2008, 12:30 PM   #25
Jason-STI
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Thanks a lot tea cup. You've been great help!

Will try to work on 'Advance' and log/monitor for awhile.

Just so that there is no misunderstanding i did post the same issues on OSEcu forum earlier and have posted my log for ev8siv3 to comment.

Thanks again.
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