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Old 09-04-2008, 04:36 AM   #1
TROLL
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Default How to interpret / respond to FLKC, and FLKC Min Load value?

A couple questions that I haven't been able to find (or at least grasp) answers to by searching...

1) It seems that most tuners (and Subaru) agree that the minimum load to look for FKC and FLKC should start at 1.0 load or similar. This is what I have always done as well.
I lowered this to .6 recently and found that the ECU was reporting knock regularly down there... is it possible that my car has been real unhappy below 1.0 load for a long time and I've just not known about it? Or maybe a lot of cars out there are the same? Or, is there a reason we only look for knock about 1.0 load and I should ignore it?
I don't have a log of the situation but if it would be helpful I can lower the minimum again and go out and take another log.

2a) When I log FLKC, that is the ECU picking a broad area to pull timing longer term. I read the Knock sticky but I wasn't able to conclude how quickly the ECU will advance timing if things look like they're in the clear. Will it go back to 0 almost immediately if it doesn't see any more knock, or will it advance back to 0 slower than that? Mine is going from -2 and advancing back in the .35 increments but usually sticks at -.95 or -.6 lately. It seems like this would indicate I need to remove this much timing in those areas.

2b) Further, when you see FKC, it is easy to ID exactly at what point the problem occurred and make the adjustments accordingly to that specific area, and probably smooth the surrounding area. However with FLKC it pulls timing from, for example, .9 to 1.3 load between 2400 and 3200 rpm. This is a pretty broad area so when you see this do you just say F it and pull timing from this entire area, or is there a way to know more precisely where the problem is occurring within this range?

Gracias...
Bryan
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Old 09-04-2008, 04:39 AM   #2
TROLL
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Default

Not sure if I should continue here or start a new thread, but I'll try continuing here...

more specifically to those questions, what do you make of this?
I continue to get cruising FLKC on the highway. It is between the .9 and 1.3 load and 2400 to 3200 rpm. I have my rom set up to only look for FKC and FLKC above 1.0 load so for all I know its happening earlier as well, but I discussed that above.

Here is my current base timing map just to get an idea, and also I took a screenshot of the comparison of my current map vs. a map from a week or so ago... it shows the timing I have pulled since trying to rid myself of the knock in this range. It only pulls -2 which is what I have it set up to pull per knock event, but I just cant get it to go away. It went down to -.6 on my short drive to work. It normally wont happen until I've got 20 or 30 minutes of driving in, but eventually it does pop up each time. Is the problem elsewhere or should I continue to pull timing in this area? My concern is that I've already pulled too much (compared to stock) and its counterproductive at this point.

Current (I know, without advance or the whole rom doesnt tell the whole story, but its a quick visual idea). Full ROM attached at bottom of thread if anyone is so motivated to check it out...


Recent Changes (cruising changes as well as some WOT that was fixed with the timing changes there)


If anyone is interested in checking out my latest ROM let me know and I can email it over.
Thanks in advance..
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Old 09-05-2008, 12:23 AM   #3
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Default

Quote:
Originally Posted by Wrinkleboi View Post
A couple questions that I haven't been able to find (or at least grasp) answers to by searching...

1) It seems that most tuners (and Subaru) agree that the minimum load to look for FKC and FLKC should start at 1.0 load or similar. This is what I have always done as well.
I lowered this to .6 recently and found that the ECU was reporting knock regularly down there... is it possible that my car has been real unhappy below 1.0 load for a long time and I've just not known about it? Or maybe a lot of cars out there are the same? Or, is there a reason we only look for knock about 1.0 load and I should ignore it?
I don't have a log of the situation but if it would be helpful I can lower the minimum again and go out and take another log.
As a counterexample, my NA car starts FLKC as 0.65g/rev and does detect a crap load of knock between there and ~0.90g/rev.

The 1.0g/rev lower bound on yours could be for a number of reasons. Perhaps they wanted to save the resolution for higher loads where the engine is more likely to damage itself. Perhaps they knew that the knock sensor picked up false knock below that point. Perhaps they just didn't think the engine wold destroy itself down there even if it did knock.

Quote:
I read the Knock sticky but I wasn't able to conclude how quickly the ECU will advance timing if things look like they're in the clear.
The ECU will advance the timing by the FLKC timing advance step each time the car has been in that particular FLKC cell long enough for the FLKC advance delay counter to fill up. If you are at steady state and it takes a ping, you'll see it recover stair step fashion right back to where it should be assuming it doesn't knock again. However, if you're changing which FLKC cell you're in (for instance, accelerating), you'll likely not be in that cell long enough for the counter to fill. There's a good chance you won't see upwards movement in that cell until the next time you happen to visit it.

Quote:
sticks at -.95 or -.6 lately. It seems like this would indicate I need to remove this much timing in those areas.
That's the most likely situation. Presuming that your IAM is at 1.000/16, the amount of FLKC is the total amount of timing it's pulling. However, if it's pulling less than 1*, I wouldn't bother with it. The other possibility is that you're simply not driving through those load cells enough for the ECU to ever learn the timing back.

Quote:
2b) Further, when you see FKC, it is easy to ID exactly at what point the problem occurred
The theory is very simple, the implementation is a pain in the butt. Basically, any time you see a downwards movement in IAM, FBKC, or FLKC, that's a knock event at that specific RPM and load. It's really easy to see this happen in IAM and FBKC. FLKC, however, is a bitch, due to the FLKC table. Basically, you're going to have to keep track of what the current value of every cell of the FLKC table is. If you see a downwards movement of FLKC, you're going to have to determine if you just moved from one cell to another or wither that cell just took a hit.
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Old 09-05-2008, 12:25 AM   #4
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Just a suspicion here... is the ".9 and 1.3 load and 2400 to 3200 rpm" range where you'd be cruising on the freeway up a slight hill or into a headwind? The modern cars seem to run a crapton of timing in the freeway cruise ranges. This is a HUGE HUGE boost to fuel economy and so long as the engine blows out of warranty, it's good for the bottom line. On my car, reducing the timing in those cells to the point of stopping the knock cost me 6pmg. Adding timing back until I only knock 25% of the time gained me back 2mpg.
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Old 09-08-2008, 11:20 PM   #5
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i've never heard of anyones car blowing up while they were cruising down the freeway

you can try to keep reducing it to see if it goes away.....

if that doesnt work, try increasing the timing....sometimes decreasing it is not the answer.

if that doesnt work, try pulling some timing via the IAT Comp Table....maybe its only happening when your IAT's rise.

have you changed your tip in enrichment table? if not, then maybe your dumping too much fuel during slight throttle changes

Last edited by Phatron; 09-08-2008 at 11:37 PM.
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Old 09-08-2008, 11:41 PM   #6
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here are my tables for reference

Code:
	0.25	0.4	0.55	0.7	0.85	1	1.15	1.3	1.45	1.6	1.75	2	2.4	2.8	3.2
800	16.91	21.84	27.81	27.46	21.13	11.99	6.72	2.85	1.8	0.39	-1.02	-1.37	-1.72	-2.42	-3.48
1200	21.84	27.81	33.09	32.73	27.11	20.78	12.7	7.77	6.02	3.91	1.09	0.74	0.39	0.04	-0.31
1600	27.81	33.09	35.9	35.55	32.38	26.76	19.73	11.64	7.07	4.96	2.85	1.09	0.74	0.39	0.04
2000	33.09	38.01	40.12	39.77	37.3	29.92	23.24	19.02	15.16	10.23	8.12	7.07	6.02	4.96	4.61
2400	38.01	46.09	46.09	42.93	40.47	30.62	23.59	19.38	15.51	11.29	9.18	8.12	7.07	6.02	5.66
2800	39.06	46.09	46.09	42.93	40.47	30.98	23.95	19.73	15.86	12.34	10.23	9.18	8.12	7.07	6.72
3200	40.12	46.09	46.09	42.93	40.47	31.33	24.3	20.08	16.21	12.7	10.59	9.53	8.48	7.42	7.07
3600	40.12	46.09	46.09	42.93	40.47	31.68	24.65	20.43	16.56	13.05	10.94	9.88	8.83	7.77	7.42
4000	40.12	46.09	46.09	42.93	40.47	32.03	25	20.78	16.91	14.45	11.64	10.59	9.18	8.12	7.77
4400	40.12	46.09	46.09	42.93	40.47	34.84	27.46	23.59	20.08	16.56	15.16	14.1	11.99	10.23	9.18
4800	40.12	46.09	46.09	42.93	40.47	35.90	28.16	24.65	20.43	16.91	15.86	15.16	14.1	11.99	10.23
5200	40.12	46.09	46.09	42.93	40.47	36.95	29.22	25.7	21.48	17.62	16.21	15.86	15.16	14.1	11.99
5600	40.12	46.09	46.09	42.93	40.47	36.95	30.27	26.76	22.19	18.67	16.21	16.21	15.86	15.16	14.1
6000	40.12	46.09	46.09	42.93	40.47	36.95	31.33	27.81	23.24	19.73	16.21	16.21	16.21	15.86	15.16
6400	40.12	46.09	46.09	42.93	40.47	36.95	33.09	28.87	23.95	20.78	16.21	16.21	16.21	16.21	15.86
6800	40.12	46.09	46.09	42.93	40.47	36.95	33.09	30.62	26.05	21.84	16.21	16.21	16.21	16.21	16.21
7200	40.12	46.09	46.09	42.93	40.47	36.95	33.09	30.62	26.05	21.84	16.21	16.21	16.21	16.21	16.21
7600	40.12	46.09	46.09	42.93	40.47	36.95	33.09	30.62	26.05	21.84	16.21	16.21	16.21	16.21	16.21
Code:
	0.25	0.4	0.55	0.7	0.85	1	1.15	1.3	1.45	1.6	1.75	2	2.25	2.5	2.75	2.9
800	0	0	0	0.35	0.7	1.05	2.11	3.16	3.87	4.92	5.98	5.98	5.98	5.98	5.98	5.98
1200	0	0	0	0.35	0.7	1.05	2.11	3.16	3.87	4.92	5.98	5.98	5.98	5.98	5.98	5.98
1600	0	0	0	0.35	0.7	1.05	2.11	3.16	3.87	4.92	5.98	5.98	5.98	5.98	5.98	5.98
2000	0	0	0	0.35	0.7	1.05	2.11	3.16	3.87	4.92	5.98	5.98	5.98	5.98	5.98	5.98
2400	0	0	0	0.35	0.7	1.05	2.11	3.16	3.87	4.92	5.98	5.98	5.98	5.98	5.98	5.98
2800	0	0	0	0.35	0.7	1.05	2.11	3.16	3.87	4.92	5.98	5.98	5.98	5.98	5.98	5.98
3200	0	0	0	0.35	0.7	1.05	2.11	3.16	3.87	4.92	5.98	5.98	5.98	5.98	5.98	5.98
3600	0	0	0	0.35	0.7	1.05	2.11	3.16	3.87	4.92	5.98	5.98	5.98	5.98	5.98	5.98
4000	0	0	0	0.35	0.7	1.05	2.11	3.16	3.87	4.92	5.98	5.98	5.98	5.98	5.98	5.98
4400	0	0	0	0.35	0.7	1.05	2.11	3.16	3.87	4.92	5.98	5.98	5.98	5.98	5.98	5.98
4800	0	0	0	0.35	0.7	1.05	2.11	3.16	3.87	4.92	5.98	5.98	5.98	5.98	5.98	5.98
5200	0	0	0	0.35	0.7	1.05	2.11	3.16	3.87	4.92	5.98	5.98	5.98	5.98	5.98	5.98
5600	0	0	0	0.35	0.7	1.05	2.11	3.16	3.87	4.92	5.98	5.98	5.98	5.98	5.98	5.98
6000	0	0	0	0.35	0.7	1.05	2.11	3.16	3.87	4.92	5.98	5.98	5.98	5.98	5.98	5.98
6400	0	0	0	0.35	0.7	1.05	2.11	3.16	3.87	4.92	5.98	5.98	5.98	5.98	5.98	5.98
6800	0	0	0	0.35	0.7	1.05	2.11	3.16	3.87	4.92	5.98	5.98	5.98	5.98	5.98	5.98
7200	0	0	0	0.35	0.7	1.05	2.11	3.16	3.87	4.92	5.98	5.98	5.98	5.98	5.98	5.98
7600	0	0	0	0.35	0.7	1.05	2.11	3.16	3.87	4.92	5.98	5.98	5.98	5.98	5.98	5.98

Last edited by Phatron; 09-09-2008 at 04:53 PM.
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Old 09-09-2008, 04:57 PM   #7
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Bryan,

Dont forget that you have to reset the ECU to clear the FLKC tables.....if you dont it will appear that the knock is still there even though you lowered the timing.

Also, here is my IAT Comp Table

Code:
-40	-22	-4	14	32	50	68	86	104	122	140	158	176	194	212	230
0	0	0	0	0	0	0	0	-2.11	-3.16	-4.22	-5.27	-7.03	-9.14	-11.25	-13.36
coolant temp i have pulling

Code:
212     230
-1.05    -3.16
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Old 09-09-2008, 06:07 PM   #8
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Quote:
Originally Posted by Phatron View Post
Bryan,

Dont forget that you have to reset the ECU to clear the FLKC tables.....if you dont it will appear that the knock is still there even though you lowered the timing.

Also, here is my IAT Comp Table

Code:
-40	-22	-4	14	32	50	68	86	104	122	140	158	176	194	212	230
0	0	0	0	0	0	0	0	-2.11	-3.16	-4.22	-5.27	-7.03	-9.14	-11.25	-13.36
coolant temp i have pulling

Code:
212     230
-1.05    -3.16
Would these ^^^ negative values would br reflected in the FLKC learning table (romraider)????
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Old 09-09-2008, 06:45 PM   #9
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I dont believe so....its not knock correction, more like knock prevention.

Its basically just applied in the timing equation

Total Timing = base + advance + coolant comp + IAT comp + FLKC + FBKC + etc

I just logged about 10 miles and didnt have on hit of FBKC or FLKC.

The FLKC values are applied all the time no matter the IAT or coolant temp, whereas the timing compensations are only applied under the specified conditions.
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Old 09-09-2008, 08:22 PM   #10
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Ron,
I've found that when I reflash my ECU it resets the ECU at the same time. I didn't realize this wasnt the case for everyone so I have been checking lately and mine does reset.
My IAT and Coolant Temp compensation are both set up similarly to yours.
I would think the IAT and Coolant Temp compensations would show up through the KC parameter, but not FKC or FLKC.

I was making great progress on things and had almost totally clean logs for a while, and now its pretty 'dirty' again... wondering if its just variances in gas that may be affecting it. If anything weather is wetter and colder lately if that may also play a role.

Most of this has been one showing up one knock count at a time (pulling 2 degrees of FLKC in response) but today on the way to work the car pulled 8 degrees! WTF... out of nowhere. Bad car, bad. I'm not really sure what to think to be honest about that becuase I haven't changed my map in almost a week and haven't seen that pop up before.
I am going to reflash now with some timing changes in response to the regular FLKC I've been seeing, but that whole -8 thing has me a little confused. I pulled a bit of timing there as well (3200-4000 rpm at 1.0 load) and I'll keep an eye on it.
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Old 09-09-2008, 08:47 PM   #11
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Quote:
Originally Posted by Wrinkleboi View Post
1) It seems that most tuners (and Subaru) agree that the minimum load to look for FKC and FLKC should start at 1.0 load or similar. This is what I have always done as well.
I lowered this to .6 recently and found that the ECU was reporting knock regularly down there...
Heya Bryan,

I just had a squiz at my ADM 2002 STi map and noticed the following factory default settings:

Feedback Knock Correction Minimum Load
disabled below 0.5
enabled above 0.6

Feedback Correction Range (Load)
disabled below 0.5
enabled above 0.6
enabled below 2.3
disabled above 2.4

I'm unsure if this is the minimum load setting of all STi's or just ADM STi's due to the different (sunny ) weather we have in AU.

So going by this, considering that Subaru lower it on the ADM STi's and they don't experience knock during low load, if you have lowered your settings to the same and you are experiencing knock then I'd look at correcting it just to be safe
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Old 09-09-2008, 09:43 PM   #12
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bryan,

i was going over your rom again and i noticed you took out your ol/cl delay and changed some of the other tables...
i think your issue is fueling, not the timing.

try putting all the tables under the OL/CL fueling transition back to stock values and see if that helps. this should help increase your gas mileage at least
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