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Old 04-13-2018, 09:29 PM   #1
blamson
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Default Feedback Knock and Fine Knock Learn not at WOT

Some short logs:
https://datazap.me/u/bnejad/log45
https://datazap.me/u/bnejad/log46
https://datazap.me/u/bnejad/log47

I was driving from work hitting some traffic, so I was driving pretty slowly for past 10 minutes or so. I don't think I even hit positive boost. Anyways, 10 minutes in I started taking a log after I saw fine knock learn hit -6.XX and saw some feedback knock flash by just randomly. I didn't go WOT or do anything special, just normal driving. Then I started noticing every time I would stop and then move forward, I would see -4.xx Fine Knock Learn while easing the clutch into 1st. I'm not burning up the clutch or anything - just normal stop and go. While seeing that, I was not seeing any feedback knock which struck me as weird. I stopped at a store briefy and the journey home I wasn't seeing the same thing.

One thing I've noticed lately is I will see Feedback Knock of -1.05 almost every drive even when I'm not using A/C or Defrost.

Only thing that's changed recently is I installed springs, rear sway, and new wheels.

Protuned by a reputable shop for about 5-6k miles. Car has 40k miles.

Engine Mods:
ProcessWest Verticooler (TMIC)
PRL TGV and EGR Deletes
PRL 3” Intake and box
Cobb EBCS
ETS Catted J-Pipe
Corsa catback
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Old 04-13-2018, 09:43 PM   #2
anarekist
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Could be a bad batch of gas or change recently in the weather
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Old 04-13-2018, 09:50 PM   #3
simpleJ
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I don’t have to read a word of this post aside from the title: It’s fine, ignore it.

Search my post history there are multiple posts on knock control in these vehicles. They should help you understand

Ps. Bet I can guess your tuner based on that feedback knock value
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Old 04-13-2018, 10:48 PM   #4
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I have a 2016 WRX running stage 2 MAPerformance 93 Octane tune and I see -1.41 feedback knock quite a bit..(never while getting on throttle) from what I read -1.41 seems to be nothing to worry about but there is so much back and forth around about it. I just don't beat on my car until I can drop 600 on a protune
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Old 04-13-2018, 10:55 PM   #5
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I get -1.41 to -2.82 fbk and fkl repeatedly if I drive constantly around 3k rpm and <20% throttle up a slight incline. I can watch the numbers pop up and learn out within a couple of seconds and repeat (can be back to back to back). Not an issue except you can feel it through the seat. Feels like the clutch is slipping or I can't hold the pedal steady but it is from the timing being pulled and re-added.

I'll just keep am eye out to see if it worsens or if you sort yours out.

I'm stage 1 91 from MAP, but running 93 octane fuel.

I am aware of the aggressive knock mitigation strategies by Subaru and they are similar to how my MINI was, but the slight lurching is a little annoying.

Last edited by nine5raptor; 04-13-2018 at 11:13 PM.
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Old 04-13-2018, 11:15 PM   #6
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[quote=nine5raptor;45614733] nm. I give up. The app is not working for me posting tonight.
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Old 04-13-2018, 11:26 PM   #7
blamson
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Quote:
Originally Posted by simpleJ View Post
I don’t have to read a word of this post aside from the title: It’s fine, ignore it.

Search my post history there are multiple posts on knock control in these vehicles. They should help you understand

Ps. Bet I can guess your tuner based on that feedback knock value
I'm aware these cars have their usual false knock characteristics but it doesn't make sense this started happening randomly.
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Old 04-14-2018, 12:18 AM   #8
simpleJ
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Quote:
Originally Posted by blamson View Post
I'm aware these cars have their usual false knock characteristics but it doesn't make sense this started happening randomly.
It’s not false, it’s real.
It makes perfect sense that it can start randomly becuase there’s hundreds of variables at play.

Be glad you’re seeing any knock at all, your sensors are turned down globally.

If there’s low load, low issue. Put the ap in the glove box and move on with your lives (all of you, seriously, you’re not doing yourselves any favors by looking at it, you’re probably just drinking more and losing sleep)
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Old 04-14-2018, 01:32 AM   #9
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Quote:
Originally Posted by simpleJ View Post
It’s not false, it’s real.
It makes perfect sense that it can start randomly becuase there’s hundreds of variables at play.

Be glad you’re seeing any knock at all, your sensors are turned down globally.

If there’s low load, low issue. Put the ap in the glove box and move on with your lives (all of you, seriously, you’re not doing yourselves any favors by looking at it, you’re probably just drinking more and losing sleep)
I guess what I'm trying to say is, I want to understand what combination of variables is causing this. It's quite abnormal considering its the only drive that its ever happened, as my ap is in view. The fact that it was happening whenever I was easing off into first so consistently.
I'm not really all that concerned the car is going to blow up.
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Old 04-14-2018, 07:11 AM   #10
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To give you some perspective... I have been trying to understand 'what combination of variables causes this' on my Subarus (and recent/current gen Subarus in general) for 10+ years... gave up trying or caring (like simpleJ suggests) a few years ago.

Along the way I leared more about these motors, their sensor array, wiring harnesses and ECU control logic (especially knock strategies) than I ever cared to know. The kicker - I am no better for it. The more I know, the less I understand and the more questions I have. It's a thankless bottomless rabbit hole.
Most Subaru engineers have no clue either... Japan headoffice had the control logic outsourced to whoever does Denso and Hitachu xCU control system for them (typical for this industry).

Ironically as the knowledge piles on, the less it makes sense in layman terms and the more counterintuative it becomes. Ultimately, its useless knowledge - unless you want to become a t00ner, work for CoBB, Ecutek, or similar.
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Old 04-14-2018, 07:39 AM   #11
simpleJ
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^ yup. All it's good for is nothing... except for not having anxiety about what your ap knock values are. Also attained by putting your ap in the glovebox.

Your knock sensors are "turned down" though, just FYI. That may more may not cause a problem. Whom'st tuned you? I am keeping a naughty list of tuners for my own use, I'd like to add them if they're not already on it.

Anyways, here you are, from another thread, in layman's terms as what you see in your AP:
Quote:
Originally Posted by simpleJ View Post
Wall o' text incoming:
No-

There are 3 knock "programs" in the tune.

-feedback knock which detects noise and will pull timing instantaneously

-Fine knock learn which both detects noise and will pull timing instantaneously and then applies that correction to the load range in the future until it the ecu sees that the car can progress through that load range without any knock at which point it is learned back in .35 increments at a time.

-DAM which applies global adjustments to timing based on consistent repeatable knock at certain loads. DAM and FKL can work together, but not always, and you can get a FKL without DAM drop. However, when you see DAM drop usually you would see a repeatable FKL that wasnt learned out or that hits at a certain load range

Okay with that high level knowledge we can apply this practically to what you see driving around and specifically to everyone's cars:

Feedback knock should be popping up basically EVERY TIME you drive the car if your knock sensors are active and not overly desensitized, you have your TGV and EGR still in place, and you are on pump gas.

FKL will occur at high loads, so boosting 6th gear up hill at like 50, 3rd and 4th gear pulls depending on temp and load.

DAM should drop if you're heat soaking, have bad gas, etc etc

So let's apply this to your car directly, bigfx:

You are seeing lots of cruise FKL- this could be because of the way you are driving the car, because you deleted EGR and not TGV and did not make adjustments, or just because we are on crap winter blend gas right now.

Deleting EGR is technically okay because while you increase timing during cruise, cylinder pressures are already fairly low and the car will just learn out that timing, which is probably what you are seeing. EGR is not active under wot so it won't hurt anything under boost. the FKL being applied could be learned knock. So I would leave your EGR plugged and reflash erase the memory and drive and log again.

Alternatively something could be loose under your tmic, or you may have spun a bearing which could cause false knock. But all that being said I would wager it is the reason above.

Tl;DR: Wipe your learning, leave egr plugged in, drive around for a week and report back

Last edited by simpleJ; 04-14-2018 at 07:44 AM.
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Old 04-14-2018, 08:13 AM   #12
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Quote:
Originally Posted by Perscitus View Post
To give you some perspective... I have been trying to understand 'what combination of variables causes this' on my Subarus (and recent/current gen Subarus in general) for 10+ years... gave up trying or caring (like simpleJ suggests) a few years ago.

Along the way I leared more about these motors, their sensor array, wiring harnesses and ECU control logic (especially knock strategies) than I ever cared to know. The kicker - I am no better for it. The more I know, the less I understand and the more questions I have. It's a thankless bottomless rabbit hole.
Most Subaru engineers have no clue either... Japan headoffice had the control logic outsourced to whoever does Denso and Hitachu xCU control system for them (typical for this industry).

Ironically as the knowledge piles on, the less it makes sense in layman terms and the more counterintuative it becomes. Ultimately, its useless knowledge - unless you want to become a t00ner, work for CoBB, Ecutek, or similar.
AND SIMPLEJ,

THANKS for what I m reading is one of the clearest explainations of this often seen question (which I would have too if my recent tune showed the OP er values). I now get an idea why it is never fully answered. I didn t realize that very few people understand this ECU tuning thing deeply. As I have started studying the subject I thought maybe I was not as bright as I thought (LOL) because I couldn t grasp the full picture on some of this. I was once told to put the AP in the glove box and was a little insulted. So do you really believe Cobb has it down totally as far as knowledge? I would hope so. That would limit who s tune I would put on my car for sure.
You guys are right too that I see too much internet BS where everyone s tune is the best and everyone of them knows fully what they are doing.
You two guys should put up a long post about this all in one spot if you haven t already. I don t know where you got all your knowedge from but it seems to be the best I ve heard on this topic. Thanks.
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Old 04-14-2018, 08:28 AM   #13
simpleJ
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You can read until you’re blue in the face but until you’ve been in the ecu, it’s not going to help.


Tuners suck. I once had an argument with a tuner in Quebec over the factory break point for AF learning 1. I was literally looking at the factory map in ATR. Like the data was right in front of me. Some of them lie to you, and others will do irresponsible crap in your ecu. Like desensitize your knock sensors so you don’t call them with questions like the above, or so they can make 20 more hp than the next tuner.

Cobb knows a lot but they don’t know everything. They leverage a lot of tuners for hive knowledge.

Last edited by simpleJ; 04-14-2018 at 08:56 AM.
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Old 04-16-2018, 09:56 AM   #14
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Quote:
Originally Posted by simpleJ View Post
Put the ap in the glove box and move on with your lives (all of you, seriously, you’re not doing yourselves any favors by looking at it, you’re probably just drinking more and losing sleep)
Best advice on here. If you have a tune from a tuner you trust and the car has been running fine, take your AP and put it away. I can guarantee you will enjoy the car more without the AP on display. I've been on pretty much the same tune for 40,000 miles. AP hasnt been on display since about 10,000 miles in.
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Old 04-16-2018, 11:54 AM   #15
BobbyDUBRX13
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Do what I did and stop monitoring them on your AP and just watch your DAM...
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Old 04-16-2018, 01:31 PM   #16
Krahooligan
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put the Cobb AP in the glove box and drive the car.
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Old 04-16-2018, 01:40 PM   #17
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DAM/IAM monitoring is useless without a wide context of the tune, conditions when RC triggers or fails to trigger a re-eval of DAM/IAM.

A DAM/IAM thats rock solid pegged at 1, means nothing without context and does not mean great, stable tune.

A DAM/IAM that fluctuates also means nothing without context and does not mean a botched, bad, unsafe tune.

A DAM/IAM pegged at 0 or any value between 0 and 1 and unable to recover back closer or to 1 also means nothing without context of tune. Its neither good or bad.
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Old 04-22-2018, 09:33 AM   #18
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Quote:
Originally Posted by PiLa View Post
I have a 2016 WRX running stage 2 MAPerformance 93 Octane tune and I see -1.41 feedback knock quite a bit..(never while getting on throttle) from what I read -1.41 seems to be nothing to worry about but there is so much back and forth around about it. I just don't beat on my car until I can drop 600 on a protune
I have two different protunes on my car that were done on a dyno in my state. From the 1st tuner I see a knock -1.41 often. This also gets set off when hitting a/c button or if I am close to a Jersey barrier and shift and the bov is loud enough it echoes off the barrier causing a false knock. The 2nd tune the car rarely knocks -1.04 when I mention rarely I mean out 30 drives the car will knock once or twice. I am not sure if the tuner possibly turned down the knock sensor sensitivity or if that is possible. The 2nd tune is a higher power tune and its tuned to 21psi, 93 octane and boost by gear
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Old 04-22-2018, 12:21 PM   #19
simpleJ
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Quote:
Originally Posted by joedreamliner787 View Post
I have two different protunes on my car that were done on a dyno in my state. From the 1st tuner I see a knock -1.41 often. This also gets set off when hitting a/c button or if I am close to a Jersey barrier and shift and the bov is loud enough it echoes off the barrier causing a false knock. The 2nd tune the car rarely knocks -1.04 when I mention rarely I mean out 30 drives the car will knock once or twice. I am not sure if the tuner possibly turned down the knock sensor sensitivity or if that is possible. The 2nd tune is a higher power tune and its tuned to 21psi, 93 octane and boost by gear
Your second tune has knock sensor reduction.
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Old 04-22-2018, 01:52 PM   #20
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Do we know which of the more popular tuners adjust the sensitivity of knock sensors? Ron, Bren, etc? Ian from MAP has said they don’t. Curious if that information is out there for the others.
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Old 04-22-2018, 03:38 PM   #21
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Quote:
Originally Posted by simpleJ View Post
Your second tune has knock sensor reduction.
That is what I am thinking unless he is that good
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Old 04-22-2018, 09:18 PM   #22
simpleJ
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Quote:
Originally Posted by dusty_sombero View Post
Do we know which of the more popular tuners adjust the sensitivity of knock sensors? Ron, Bren, etc? Ian from MAP has said they don't. Curious if that information is out there for the others.
Yes we do.

All of them- but its more complicated than that.


I would need to post the tables to make sense, but basically you can cut the nuts off all the knock sensing- that is the problem. Bren I know for a fact does not do this. I don't believe ron does either.
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Old 11-20-2019, 06:48 PM   #23
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Quote:
Originally Posted by simpleJ View Post
^ yup. All it’s good for is nothing... except for not having anxiety about what your ap knock values are. Also attained by putting your ap in the glovebox.

Your knock sensors are “turned down” though, just FYI. That may more may not cause a problem. Whom’st tuned you? I am keeping a naughty list of tuners for my own use, I’d like to add them if they’re not already on it.

Anyways, here you are, from another thread, in layman’s terms as what you see in your AP:
Question SimpleJ... seeing as you seem quite up to speed on tuners, I am curious if you could give me a recommendation for a tuner in Arizona or California who is reliable. Headed out there in the near future. Currently running a tune by Drunkmann Tuning if you are familiar with Anthony J. Berry? Any help and advice would be greatly appreciated, thanks.
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Old 11-20-2019, 07:52 PM   #24
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My first tune was by Calvin at EFI logics in CT. 2nd tune was done by Mike Botti. Both on the dyno in CT. I like Calvin's tune more and just stayed on it. He does not add knock reduction. Botti does boost by gear and the car feels slower than Calvin's tune. Calvin spent a good amount of time in my car and he was very honest and answered all of my questions. Hope that helps
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Old 11-20-2019, 08:07 PM   #25
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Quote:
Originally Posted by Q-101 View Post
Question SimpleJ... seeing as you seem quite up to speed on tuners, I am curious if you could give me a recommendation for a tuner in Arizona or California who is reliable. Headed out there in the near future. Currently running a tune by Drunkmann Tuning if you are familiar with Anthony J. Berry? Any help and advice would be greatly appreciated, thanks.
Im not simpleJ but if you want reliable go with ron watson.
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