*** Knock, do you have any?

[NSFW]

Your "how-to's" are awesome, NSFW. I think the mods in this forum really ought to sticky a couple of them (maybe if you posted them here also they would??)

 

Thanks! I could post a 'table of contents' here, but I want to keep the articles in one place so that I don't need to change multiple copies when I update them. So instead I just post links to individual how-to's when they're relevant. I figure that word will spread if they deserve more attention than that.

[Legend]

^^ Makes sense to have a single copy. Nonetheless, some stickies to link off-site would be very nice for this forum.

[kholmes]

Thanks guys, just registered over there and will be reading up on how to fix this.

[fishbone]

spec.B dream, let me guess, you are in top gear, either 5th or 6th and your knock sum goes up every time you gently accelerate. That's how I get my knock sum. I slow down to 45-50mph and when I accelerate it will register ~2 knock events. I can feel the motor stutter, it's the same thing that the Boxer does when it idles. I am not sure if it is real knock or perceived knock but it does it at stock power levels, stock tune too. The load is 1.2 at most from what I remember. qikslvr had the same thing on his Legacy and there are others here as well.

I will not worry about it but I will monitor.

[LittleBlueGT]

spec.B dream, let me guess, you are in top gear, either 5th or 6th and your knock sum goes up every time you gently accelerate. That's how I get my knock sum. I slow down to 45-50mph and when I accelerate it will register ~2 knock events. I can feel the motor stutter, it's the same thing that the Boxer does when it idles. I am not sure if it is real knock or perceived knock but it does it at stock power levels, stock tune too. The load is 1.2 at most from what I remember. qikslvr had the same thing on his Legacy and there are others here as well.

I will not worry about it but I will monitor.

 

Logs of that? Sounds like real knock to me.

[fishbone]

Sure, here is one when I am modulating the throttle to get the knock sum to increment. From a while ago when other stuff was wrong, such as IAM not being 1, but for all intents and purposes it is showing the exact same thing, more or less, that I am seeing now. RPMs under 3K, load right arount .9-1.2 or so.

http://legacygt.com/forums/attachment.php?attachmentid=78184&d=1261622300

Possibly due to rapidly changing load, beats me. qikslvr rode shotgun with me recently, couldn't pinpoint why there would be this cruising knock/light acceleration. I don't have those logs handy but I can post them up if you are curious. Even got 1 knock even when braking down at a light.

Edited May 24, 2010 by fishbone

[LittleBlueGT]

Sure, here is one when I am modulating the throttle to get the knock sum to increment. From a while ago when other stuff was wrong, such as IAM not being 1, but for all intents and purposes it is showing the exact same thing, more or less, that I am seeing now. RPMs under 3K, load right arount .9-1.2 or so.

http://legacygt.com/forums/attachment.php?attachmentid=78184&d=1261622300

Possibly due to rapidly changing load, beats me. qikslvr rode shotgun with me recently, couldn't pinpoint why there would be this cruising knock/light acceleration. I don't have those logs handy but I can post them up if you are curious. Even got 1 knock even when braking down at a light.

 

That is not the cruise knock I speak of. That is happening on throttle tip-in. Notice your g/s is going from 5 - 40 or something like that? FWIW in a lot of those cells you are running 29 degrees total timing, whereas I am running about 25.

 

Could be a tip-in problem, IDK for sure. But I would try running less timing in the 1.2 load 2300 rpm'ish range.

 

Cruise knock for me was 3000 rpm, 80 mph steady state, and the knock sum would increment. Not this! When you are messing around with the throttle like that it is not called cruise.

 

When you drive normal, is it affecting anything?

[RIPjeep2002]

Sure, here is one when I am modulating the throttle to get the knock sum to increment. From a while ago when other stuff was wrong, such as IAM not being 1, but for all intents and purposes it is showing the exact same thing, more or less, that I am seeing now. RPMs under 3K, load right arount .9-1.2 or so.

http://legacygt.com/forums/attachment.php?attachmentid=78184&d=1261622300

Possibly due to rapidly changing load, beats me. qikslvr rode shotgun with me recently, couldn't pinpoint why there would be this cruising knock/light acceleration. I don't have those logs handy but I can post them up if you are curious. Even got 1 knock even when braking down at a light.

 

That sounds like me too. Crusing on the highway, 5th gear, 60mph, go to accelerate, and look at my AP and can see timing being pulled, along with feeling some slight shutter until I am up over 70mph.

 

I fixed this problem by down shifting into 4th, or staying in 4th gear until I am over 70mph

[fishbone]

^Yep, same exact thing.

LBGT: dead on steady pedal no knock.

[LittleBlueGT]

^Yep, same exact thing.

LBGT: dead on steady pedal no knock.

 

You can try and tune that out, just the fact that I am running 4 or 5 degrees less timing there should help you out as a starting point. Also nice to see AFRs there. If it is going a bit lean, address that first, if not then timing. (unless AVCS is really weird there, but no reason to have much different then OEM values at 1.2 load).

 

I can feed the throttle on all I want in 5th, and I might get 1 or 2 counts of knock, but never usually much more then 1 or none.

[spec.B Dream]

Attached is a log of my drive in on the highway this morning. I've identified the knock events that, based on context, seem to be cruise knock to me in the "knock" column with the letter "a".

 

I've also attached screenshots of my cruise and non-cruise total timing.

 

What do you think, cruise knock, or something I should be worried about?

 

Oh, I should also mention I'm running an ERZ catless downpipe, the 08 spec.B stage 2 tune from RomRaider, and am otherwise stock.

Thanks,

Andy

romraiderlog_20100525_075320.csv

Edited May 25, 2010 by spec.B Dream
Can't filter .csv files

[LittleBlueGT]

Attached is a log of my drive in on the highway this morning. I've identified the knock events that, based on context, seem to be cruise knock to me in the "knock" column with the letter "a".

 

I've also attached screenshots of my cruise and non-cruise total timing.

 

What do you think, cruise knock, or something I should be worried about?

 

Oh, I should also mention I'm running an ERZ catless downpipe, the 08 spec.B stage 2 tune from RomRaider, and am otherwise stock.

Thanks,

Andy

 

I see nothing that even remotely worries me in that log.

[Dirtrace95]

You mention the "learning view" utility but I think it deserves a little more detail. And I could use a sanity check on my own understanding of it - so if this is wrong please let me know:

 

The Learning View utility will display your Fine Learning Knock Correction (FLKC) table, which shows the RPM/Load areas in which the ECU has learned to pull timing in response to knock. It will also show your Ignition Advance Multiplier (IAM), which should be 1.0 but will drop if your car has experienced significant knock.

 

Learning View connects to your ECU using an OpenPort 1.X or compatible cable, much like RomRaider's logger. The VAG-COM cable will probably also work, and OpenPort 2.0 compatibility is likely coming soon.

 

For more information, and a link to download the Learning View utility:

http://www.romraider.com/forum/topic2772.html

 

If you are tuning your car, you should use this periodically to see if your engine has experienced knock when you were not actively logging. If you see evidence of significant knock, it's time to reconsider your tune.

 

The stock tune will show small amounts of knock correction (-.35, -1.05, etc) occasionally in various cells, these are not cause for great concern. But IAM under 1.0, or larger corrections in the FLKC table, should be investigated. The Learning View thread (linked above) has a lot more information and examples to show how to interpret Learning View results.

 

Learning View also shows your fuel trims, which are primarily of interest if you have changed your intake tract or fuel injectors. If they're way off (more than 5%) you may want to address that, but this is another subject for another thread.

 

Note that resetting your ECU (which happens during reflashing, for most ECUs) will set IAM to 0.5 (or whatever your ROM has configured for the initial IAM) and will clear the FLKC table. Don't panic if you see a low IAM soon after a reflash.

 

There should be a thread on this subject. I use this alot for a

quick check up on the tune. On A/F#1 learning I have noted the ecm

adding fuel at the lowest 0-560 range. I have changed back to a stock

pannel filter after reading lots a Micky'd info. If your running 14.7 A/F all

over the low eng. load range why is the ecm wanting to richen things up

???. Its almost always adding over 5% Does the tune just need more

fuel in the area ??? Is the ecm adding fuel to try to keep at 14.7 A/F ???

The A/F is good in all other areas except the low load spot. This is

a open source stg-1 tune.

Edited May 26, 2010 by Dirtrace95

[NSFW]

I see nothing that even remotely worries me in that log.

 

Ditto. The only knock sum increments are at low load, low RPM, or both, so they're not cause for concern.

 

The timing is strangely jagged though, and some of the peaks are weird... 47 degrees at 1600 RPM. 15 degrees difference between 3200 and 3600 RPM at 0.5 load. Does the car feel weird when you accelerate gradually from 3000 to 4000 RPM? I wonder if it even uses the jagged table there.

 

Which one is cruise and which one is non-cruise? Have you got a rough idea of when it transitions from one to the other?

[spec.B Dream]

I see nothing that even remotely worries me in that log.

Ditto. The only knock sum increments are at low load, low RPM, or both, so they're not cause for concern.

Always nice to hear a more experienced member say no worries.

 

 

Which one is cruise and which one is non-cruise? Have you got a rough idea of when it transitions from one to the other?

The left (more jaggad) image is cruise and right is non-curise. Being new to this tuning game, I wish Subaru had kept it like the 05 and not added the table to split the timing. I really have no idea when the transition takes place. My guess would be somewhere along the lines of closed/open loop. The table properties don't really explain when each table is used. I wonder if there would be any harm in putting the same values in each table? I'll have to do some more searching to see what I can find. It is probably save to assume that if I do any wot tuning that I'd adjust the non-cruise table.

 

 

The timing is strangely jagged though, and some of the peaks are weird... 47 degrees at 1600 RPM. 15 degrees difference between 3200 and 3600 RPM at 0.5 load. Does the car feel weird when you accelerate gradually from 3000 to 4000 RPM? I wonder if it even uses the jagged table there.

It does feel weird, not a stutter or hesitation, but like I can feel the timing being adjusted. I need to look back at my stock rom and see if timing is set that way. When I get more comfortable with things, I'll probably try smoothing that out. Thanks for the responses.

[fishbone]

Ditto. The only knock sum increments are at low load, low RPM, or both, so they're not cause for concern.

That is what I saw too, rpms were 2600-2800 but load was a bit higher, at times it would be .94, others 1.2 depending on pedal position. Straight road .94, if I'd be going up a slight incline and squeeze the pedal more, it would climb.

So what is low load? I know anything under 1.0 is low, but what about 1.2-1.4?

[LittleBlueGT]

That is what I saw too, rpms were 2600-2800 but load was a bit higher, at times it would be .94, others 1.2 depending on pedal position. Straight road .94, if I'd be going up a slight incline and squeeze the pedal more, it would climb.

So what is low load? I know anything under 1.0 is low, but what about 1.2-1.4?

 

Good question. On a NA 2.5 liter 1.2 load is about as high as it will ever get! Seriously!

 

I did many hours of driving, and found I had no knock at all in the 1.0 - 1.4 load range when things where steady state. Even in mildly changing load situations there was no knock.

 

The problem came in when I would slip the clutch, like a 3000 rpm slip launch, then it would increment the knock sensor like crazy! I took out about 1.5 degrees of timing from where I really never saw knock anyways (in case of bad gas) and raised the thresholds a bit.

 

I don't know if raising the knock thresholds to 1.3 or 1.4 load is a bad idea or not, but I feel comfortable doing it.

[NSFW]

The left (more jaggad) image is cruise and right is non-curise. Being new to this tuning game, I wish Subaru had kept it like the 05 and not added the table to split the timing. I really have no idea when the transition takes place. My guess would be somewhere along the lines of closed/open loop. The table properties don't really explain when each table is used. I wonder if there would be any harm in putting the same values in each table? I'll have to do some more searching to see what I can find. It is probably save to assume that if I do any wot tuning that I'd adjust the non-cruise table.

 

If I remember correctly, there's a parameter you can log which shows how the ECU is transitioning between them. It's called "map switch ratio" or something like that.

 

For tuning, I'd make them both the same just to make logging easier. Maybe flash one of them back to stock if you get a clear understanding of when it uses which tables.

[dmanaenk]

So to start learning I've been logging stock map. Sadly I couldn't get the CAN logging patch to recognize my ecu to gain some resolution and ability to log key parameters, so I was doing it via k-line.

 

Getting lotsa knock sum increments, most are at really low loads, so it's probably just some random crap, like heat shield rattle?

But a couple of them are at mid-low-range loads (~1). Some just increment the sum (probably too bad of a resolution to catch anything), and some show up as FBKC.

 

What else should I log to figure out if it's a cause for concern?

 

WOT run looks fine. LV looks okay except for stupid-wide rpm/load ranges on the scale (that's what in stock roms right?).

excerpt.csv

Edited May 31, 2010 by dmanaenk

[NSFW]

Subaru's tuners seem to like to simplify the table by making some rows/columns unreachable. I guess that it basically it makes the knock corrections more conservative by applying each correction to a wider region. But for tuning, it's nice to know what RPM/load you need to work on, so more resolution is better.

 

You're not likely to ever exceed 10,000 RPM or 5.0 load, so they basically made 3 rows and one column irrelevant.

[dmanaenk]

Thanks,

so how much should I worry about those FBKC events?

[NSFW]

FBKC is disabled below a certain load, that's why some of those increments aren't showing up.

 

To diagnose, reduce timing in the area where you're seeing the increments, and see if that helps. I've seen some stock tunes that run pretty high timing in the low-load area, and I'm not sure why or how much knock it causes. I think mine had 45 degrees at most, and I've seen 55 degrees in other factory tunes. I took everything above 45 degrees in my tune and cut it down to 38 degrees, and that helped. It can't hurt to try, the factory tunes vary so much that I think the engine is pretty indifferent.

 

Or you could try putting in some race gas or Torco to see if the problem goes away with higher octane.

[fishbone]

-9. Omg wtf bbqthxbye

Log 14 is some of that "cruise knock" I mentioned. 5th, tq locked up, squeeze the pedal to accelerate from 50-ish to 70-ish.

datalog11.csv

datalog14.csv

[NSFW]

That -9 is odd. It's not unusual to see some knock correction when hitting the throttle, but I've never seen that much. The good news is that the ECU didn't see knock again for a while, so it 'unlearned' that correction as soon as it could.

 

Have you tried reducing timing in that part of the map to see if it helps?

[LittleBlueGT]

-9. Omg wtf bbqthxbye

Log 14 is some of that "cruise knock" I mentioned. 5th, tq locked up, squeeze the pedal to accelerate from 50-ish to 70-ish.

 

yea, that -9 is kinda big. I have never really seen that, except when I slip the clutch when car is in reverse.

 

Of course my FBKC and FLKC don't come on til about 1.1 load or so, so on my car it wouldn't have pulled any timing as you were at .8 load or so.