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Old 11-01-2019, 05:41 PM   #1
alro
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Default Cobb fine knock learn

https://i.imgur.com/15bqa28r.jpg

I got my cobb 2 days ago. Everything checked out until I was driving on neighborhood roads and I saw this. Fine knock learn was at -1.40 and dropped to -0.70 and it's staying there. How do I make sure this isn't anything bad?

Edit: it stays at 0, but when I reach 2500 rpms it goes up around -0.34
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Last edited by alro; 11-01-2019 at 07:02 PM.
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Old 11-01-2019, 10:07 PM   #2
Craigster08
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If you haven't already, I would definitely suggest reading up on Subaru's knock strategy written by Cobb. - https://www.cobbtuning.com/subaru-kn...logic-changes/

Fine knock learn is a learned correction, and will decrease in increments of .35, which is what you are currently seeing. This number will register in a specific load and RPM range. It will decrease when it feels everything is operating as normal.

Just seeing a snap shot of your knock events doesn't really tell the full story, so it is hard to say if it is anything bad or not. It could be false knock. Did you happen to mash your throttle around that 2500 rpm range? Your best bet to really know if anything is wrong would to do some data logging, especially a WOT pull.

Just to confirm, you are running an OTS tune provided by Cobb correct?
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Old 11-01-2019, 11:07 PM   #3
alro
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Quote:
Originally Posted by Craigster08 View Post
If you haven't already, I would definitely suggest reading up on Subaru's knock strategy written by Cobb. - https://www.cobbtuning.com/subaru-kn...logic-changes/

Fine knock learn is a learned correction, and will decrease in increments of .35, which is what you are currently seeing. This number will register in a specific load and RPM range. It will decrease when it feels everything is operating as normal.

Just seeing a snap shot of your knock events doesn't really tell the full story, so it is hard to say if it is anything bad or not. It could be false knock. Did you happen to mash your throttle around that 2500 rpm range? Your best bet to really know if anything is wrong would to do some data logging, especially a WOT pull.

Just to confirm, you are running an OTS tune provided by Cobb correct?
I'll read that now, thanks! Yes I'm running a cobb tune, stage 1 with k&n intake and Perrin inlet. What should I data log, and for how long? I did do like three wide open pulls two hours before that. Usually when I just rev it to 2500, it shows up. I usually switch gears at around 2500, 3000 when I'm not driving aggressively. I read it the sensor also detects when you switch to a lower gear than intended causing the sensor to activate which might have been the case.

Last edited by alro; 11-01-2019 at 11:33 PM.
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Old 11-07-2019, 07:23 PM   #4
straitstrider67
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Very normal to get false knock events at low RPMs low load. Trust me my STI does the exact same thing. But with that out of the way cobbs stage 1 tunes are for their SF intake and I think they have one for AEMs intake as well (at least for my 14 STI). I dont think they have a Tune specifically for your mods. Not the end of the world necessarily but if I were you id either swap them out for the parts that cobb specifically recommends or go to a cobb certified pro-tuner and have them dyno tune your car for your specific mods.
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Old 11-11-2019, 02:45 PM   #5
danger1138
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Quote:
Originally Posted by straitstrider67 View Post
Very normal to get false knock events at low RPMs low load. Trust me my STI does the exact same thing. But with that out of the way cobbs stage 1 tunes are for their SF intake and I think they have one for AEMs intake as well (at least for my 14 STI). I dont think they have a Tune specifically for your mods. Not the end of the world necessarily but if I were you id either swap them out for the parts that cobb specifically recommends or go to a cobb certified pro-tuner and have them dyno tune your car for your specific mods.
Very normal to get "Feedback Knock", not necessarily fine knock learn.
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Old 11-11-2019, 03:22 PM   #6
Stretch18
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Quote:
Originally Posted by danger1138 View Post
Very normal to get "Feedback Knock", not necessarily fine knock learn.
Fine knock learn is just the ecu identifying and correcting a spot in the tune that is seeing repeated knock events. Small amounts of knock learn aren't an issue.

While it's nice to have the perfect tune, changes in temp, humidity, elevation for every situation are tough to account for perfectly. But the corrections are what the ecu is supposed to do...
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Old 11-11-2019, 05:49 PM   #7
Jefe159
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There is LOADS of information about FKL and FK on this forum. You could read about it for hours and hours. I would do a bunch of reading and develop your own opinion on whats going on with your car.

With the limited info you provided it is my guess that everything is operating normally within safe parameters and like the guy above me said, the ecu is doing what it is supposed to do.

That said, take some logs and review them to make sure something isn't going on that could actually be harmful to the engine. There are many variables. Like I said, immerse yourself in the information on this forum and you'll (probably) be able to decide for yourself.
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Old 11-12-2019, 08:35 PM   #8
danger1138
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Quote:
Originally Posted by Stretch18 View Post
Fine knock learn is just the ecu identifying and correcting a spot in the tune that is seeing repeated knock events. Small amounts of knock learn aren't an issue.

While it's nice to have the perfect tune, changes in temp, humidity, elevation for every situation are tough to account for perfectly. But the corrections are what the ecu is supposed to do...
Correct, fine knock learn is pulling timing in a general load/spot within the tune where the ecu tends to see knock events regularly= consistent knock events; bad.

Piggybacking off what you mentioned: feedback knock may not even be specifically tune related. Ecu may pick up feedback knock from changes in temp, humidity, elevation etc..; not so bad/ every car on the planet sees minor knock events
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Old 11-12-2019, 11:59 PM   #9
Jersey Man10
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Its only bad going WOT (Wide Open Throttle). I sometimes get false knock at low rpm like when I'm taking off from a stop sign. Usually -1.40 sometimes -2.80 on the highway. Exhaust rattle can trigger it. The ac compressor definitely will make you "knock".

I don't worry about it anymore although I do have a custom e-tune. Just enjoy the car and don't worry about it so much like I used to do.
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Old 11-13-2019, 11:52 PM   #10
EastPhilly
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I'm wondering if I get fkl so much because my cat back portion of my stock exhaust broke all the hangers off besides the part on the muffler... I want to get a new catback soon but I really can't justify the cost over doing other mods that make actual differences in handling and such... I guess it's time to get the jb weld out and get the hangers attached again.
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Old 11-14-2019, 09:31 AM   #11
BeastianSTI
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Something I had to look into at one point:

Look for any sockets or other metal objects (hose clamps, etc) on top of your block. I had false knock readings on a car I was working on due to an old socket lodged in between some of the hard PCV breathers and the coolant crossover pipe.

What folks said about fine knock learning/feedback knock is correct. If you can, capture a data log when it happens, with a wideband o2 sensor reading included in the logs, plus timing and calculated load. That way you can determine: not enough fuel, too much timing, too much load.
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Old 11-15-2019, 08:35 PM   #12
Boost.and.freckles
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Those numbers happen. Check out Cobb's website. As long as you're not hitting those numbers or higher during non wot conditions you'll be fine
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Old 11-16-2019, 08:59 PM   #13
danger1138
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Also if you don't experience *feedback knock * during WOT pulls, you should be fine...
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Old 11-16-2019, 09:04 PM   #14
AcquaCow
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You'll always have some learned "knock" somewhere. These are noisy engines with many things that rattle and cause false knock. I always have -1.4 to -2.8 in the load columns and rpm where I shift/etc.

Best to read up on logging, log daily, post your logs to datazap.me and look at the graphs and learn to read the visual data.
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Old 11-18-2019, 11:58 AM   #15
mangineer
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If you want the reassurance, another option is you can request support via email to Cobb to review a datalog containing the event if you can re-simulate it. They've got pretty good customer service and roughly a day response time which is quick in my book.
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