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Old 03-19-2018, 06:18 PM   #1
Mkodada
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Default -11.95 feedback knock question

So today I was at a stop sign pulled out in 1st gear could not have been going more than 5mph and saw an -11.95 feedback knock. No fine knock learn and DAM is still at 1.

2018 wrx stock with COBB ots stage 1 93.

Anyone else ever experience this?

Thanks!
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Old 03-19-2018, 07:31 PM   #2
Mkodada
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Went for another ride and no feedback knock and DAM at 1 has never dropped. I am now seeing -.35 fine knock lean very low load when just lightly hitting the gas.
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Old 03-19-2018, 08:23 PM   #3
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Update:

Went on a 1/2 hr ride no feedback knock, no fine knock learn and DAM at. I am guessing that -11.95 while pulling away from the stop sign must have been false???
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Old 03-19-2018, 10:21 PM   #4
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Have had that with ots maps. Once I deleted egr and tgv and etune haven't had since. I've read that one of the knock sensors is right under hood scoop and sometimes water pools around it and can cause false readings.
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Old 03-19-2018, 10:33 PM   #5
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Did you MASH on the throttle? I've seen -6.xx Feedback Knock Correction when aggressively accelerating from cruise to high load conditions.
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Old 03-20-2018, 07:23 AM   #6
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Originally Posted by Cobrakai View Post
Did you MASH on the throttle? I've seen -6.xx Feedback Knock Correction when aggressively accelerating from cruise to high load conditions.


Not at all I was at a stop sign and was pulling away normally. If I did not have the smoothest clutch work can this cause a false knock reading?
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Old 03-20-2018, 07:40 PM   #7
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Sounds like bad clutch work translated into a lot of extra drivetraim noise that your ECU perceived as knock. False knock.

Contrary to what has been posted, water DOES NOT cause false positives, however it can short out your knock sensor.
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Old 03-20-2018, 09:00 PM   #8
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Quote:
Originally Posted by GlarryHoodDIT View Post
Sounds like bad clutch work translated into a lot of extra drivetraim noise that your ECU perceived as knock. False knock.



Contrary to what has been posted, water DOES NOT cause false positives, however it can short out your knock sensor.


Yeah I agree could not replicate the issue. I just got the MAPerformance stage 1 emailed to me.

We getting a blizzard tomorrow so hope to try it out Thursday.
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Old 09-19-2018, 11:50 AM   #9
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Default What could it be?

Hate to hijack a thread, but I only have 2 legit posts, so I can't post my own thread just yet...

I've got a 2009 Legacy GT 5MT (~59K miles) completely stock except the stage 1 93 oct tune. I've only run the tune for about a month (before that it was completely stock). I always use 93 and try to stick to Top Tier providers (lots of QuikTrips in my area).

My DAM stays at 1.0 all the time. At first, fine knock learn stayed mostly at 0 and occasionally went to -1.4. The feedback knock would stay at 0 and occasionally hit -1.4 itself. But, I've seen it slowly change to hit -2.8 and -4.2 on occasion. Just a couple of days ago, though, I saw it hit -9.8 briefly and I was really concerned. On the drive home, it hit -6.8 at one point, and I was occasionally seeing it go up to around -3 before settling back to zero. The times it was going to about -3 I was in 5th, cruising at 65mph, on either relatively flat stretch of highway or occasionally a slight incline. The AC was on the whole time (I'm in North Texas after all), though I don't recall if it was on recirculate or not. When cruise would accelerate to get up the incline, it didn't rev very high, nor did I hear a lot of noise. My calculated load hovered around 0.4 g/rev most of the time home and occasionally might hit 1.5 or 2.

I can't tell why feedback knock suddenly hit -9.8 or if I should be concerned. And I'm really not sure what to check to see if it's a simple fix.

What should I check or do?
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Old 09-19-2018, 12:56 PM   #10
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Quote:
Originally Posted by 2009LGT View Post
Hate to hijack a thread, but I only have 2 legit posts, so I can't post my own thread just yet...

I've got a 2009 Legacy GT 5MT (~59K miles) completely stock except the stage 1 93 oct tune. I've only run the tune for about a month (before that it was completely stock). I always use 93 and try to stick to Top Tier providers (lots of QuikTrips in my area).

My DAM stays at 1.0 all the time. At first, fine knock learn stayed mostly at 0 and occasionally went to -1.4. The feedback knock would stay at 0 and occasionally hit -1.4 itself. But, I've seen it slowly change to hit -2.8 and -4.2 on occasion. Just a couple of days ago, though, I saw it hit -9.8 briefly and I was really concerned. On the drive home, it hit -6.8 at one point, and I was occasionally seeing it go up to around -3 before settling back to zero. The times it was going to about -3 I was in 5th, cruising at 65mph, on either relatively flat stretch of highway or occasionally a slight incline. The AC was on the whole time (I'm in North Texas after all), though I don't recall if it was on recirculate or not. When cruise would accelerate to get up the incline, it didn't rev very high, nor did I hear a lot of noise. My calculated load hovered around 0.4 g/rev most of the time home and occasionally might hit 1.5 or 2.

I can't tell why feedback knock suddenly hit -9.8 or if I should be concerned. And I'm really not sure what to check to see if it's a simple fix.

What should I check or do?
Totally possible there was a little pinging when the cruise control accelerated.

An easy "fix" is to step down an octane level on your Stage 1 map, see if it goes away.
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Old 09-19-2018, 01:10 PM   #11
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Quote:
Originally Posted by Jewbaru View Post
Totally possible there was a little pinging when the cruise control accelerated.

An easy "fix" is to step down an octane level on your Stage 1 map, see if it goes away.
Just to clarify, do you mean go to the Stage 1 91 oct map *OR* stay on the Stage 1 93 oct map, but use 91 octane?
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Old 09-19-2018, 01:13 PM   #12
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Quote:
Originally Posted by 2009LGT View Post
Just to clarify, do you mean go to the Stage 1 91 oct map *OR* stay on the Stage 1 93 oct map, but use 91 octane?
The former, flash the 91 Octane map.
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Old 09-19-2018, 01:21 PM   #13
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Originally Posted by Jewbaru View Post
The former, flash the 91 Octane map.
Cool, will try that. And one more clarification: should I stick with running 93 octane on the stage1 91 oct map, or should I try switching to 91 oct?

Also, I keep my Cobb AP3-SUB-003 plugged in. Are there any values I should monitor (besides FB knock and fine learning) that would help me narrow down any issues?

btw, thanks for the help!
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Old 09-19-2018, 01:34 PM   #14
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Quote:
Originally Posted by 2009LGT View Post
Cool, will try that. And one more clarification: should I stick with running 93 octane on the stage1 91 oct map, or should I try switching to 91 oct?

Also, I keep my Cobb AP3-SUB-003 plugged in. Are there any values I should monitor (besides FB knock and fine learning) that would help me narrow down any issues?

btw, thanks for the help!
Yea, keep running 93 with it. If it goes away, you were probably pinging. Uphill, with cruise control, in hot weather with the AC on is probably going to detonate at least a little bit.

If it doesn't? Well... it could just be engine racket, but you'd need to run a datalog and post it (I'm not well versed in reading the logs yet, so you'd want to get your post count up so you can post a new thread.)

As far as monitors, those two and DAM cover detonation events. From there, most people watch boost, or boost target, and AF learning/correction.
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Old 09-19-2018, 02:17 PM   #15
2009LGT
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Quote:
Originally Posted by Jewbaru View Post
Yea, keep running 93 with it. If it goes away, you were probably pinging. Uphill, with cruise control, in hot weather with the AC on is probably going to detonate at least a little bit.

If it doesn't? Well... it could just be engine racket, but you'd need to run a datalog and post it (I'm not well versed in reading the logs yet, so you'd want to get your post count up so you can post a new thread.)

As far as monitors, those two and DAM cover detonation events. From there, most people watch boost, or boost target, and AF learning/correction.
I finally got access to post. I'll move any further discussion there to leave this post alone :-) ... https://forums.nasioc.com/forums/sho...6#post45784496
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