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Old 04-21-2012, 04:23 PM   #1
Nu2SubaruWRX
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Default Strange Fine Knock

My friend is datalogging and consistently gets feedback knock between 4k and 5k rpms. The fine knock isnt being learned away; it gets worse and then just stops.

I think he has some sort of rattle in the car that is affected by the vibration that exists inbetween 4k and 5k rpms. I only think this becuase from what I have seen, feeback knock is learned away. In this case, it gets worse and just stops. I have also heard that your heatshield or something else could rattle and cause this.

His car is a 2011 WRX with Stage 1 OTS NWG map, 93 octane.

All help is appreciated. Thank you.

https://docs.google.com/spreadsheet/...mZMbFU2dk5Kc0E

https://docs.google.com/spreadsheet/...WdZZFAteWhCMEE

https://docs.google.com/spreadsheet/...1hPdXYxZm5ub2c

https://docs.google.com/spreadsheet/...nU0Wjd2anh6Rnc

https://docs.google.com/spreadsheet/...EtYYzlXUjI1LWc
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Old 04-21-2012, 09:16 PM   #2
hutch959
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thats learned knock... and it looks like it is starting to decrease.
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Old 04-22-2012, 10:30 AM   #3
Cobb Tuning
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Originally Posted by Nu2SubaruWRX View Post
My friend is datalogging and consistently gets feedback knock between 4k and 5k rpms. The fine knock isnt being learned away; it gets worse and then just stops.

I think he has some sort of rattle in the car that is affected by the vibration that exists inbetween 4k and 5k rpms. I only think this becuase from what I have seen, feeback knock is learned away. In this case, it gets worse and just stops. I have also heard that your heatshield or something else could rattle and cause this.

His car is a 2011 WRX with Stage 1 OTS NWG map, 93 octane.

All help is appreciated. Thank you.

https://docs.google.com/spreadsheet/...mZMbFU2dk5Kc0E

https://docs.google.com/spreadsheet/...WdZZFAteWhCMEE

https://docs.google.com/spreadsheet/...1hPdXYxZm5ub2c

https://docs.google.com/spreadsheet/...nU0Wjd2anh6Rnc

https://docs.google.com/spreadsheet/...EtYYzlXUjI1LWc
You can sometimes see that type of fine knock learning when lifting off the throttle at the end of a WOT run. Fine knock learning is re-applied after the original event(s) until specific conditions are satisfied and it is ramped gradually back to zero.

Best thing to do in this case would be to reflash the most conservative map (91 ACN) and then do some driving for about a week. If it occurs again, then it is likely just noise.

Bill
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Old 04-22-2012, 12:15 PM   #4
erik11876
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Did your friend fool around with launch control around that RPM range? That'll do it too.
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Old 04-22-2012, 12:21 PM   #5
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Did your friend fool around with launch control around that RPM range? That'll do it too.
He hasn't touched anything inside the AP (launch control, shift light, etc.). We just decided to do some datalogging and we found that strange fine knock. We researched to no end and found nothing on knock that went from smaller values to higher in one specific range and then just went to zero. The max was always -2.8.

We flashed it to the 91 map after Bill's post and he will drive it for a week or two and then we will datalog it again. He is a very mild driver like I am, so the 91 will be no big deal.

I will post the follow-up logs next weekend or the weekend after.

If anyone else has any experience on this type of event, please share. Thanks guys for the help.
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Old 04-23-2012, 09:07 AM   #6
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Originally Posted by Nu2SubaruWRX View Post
He hasn't touched anything inside the AP (launch control, shift light, etc.). We just decided to do some datalogging and we found that strange fine knock. We researched to no end and found nothing on knock that went from smaller values to higher in one specific range and then just went to zero. The max was always -2.8.

We flashed it to the 91 map after Bill's post and he will drive it for a week or two and then we will datalog it again. He is a very mild driver like I am, so the 91 will be no big deal.

I will post the follow-up logs next weekend or the weekend after.

If anyone else has any experience on this type of event, please share. Thanks guys for the help.
It is important understand what fine knock learning is. There is a table that consists of cells that represent specific load and RPM ranges. For example, with your stage 1 map, one of the cells is 1.87-2.43 g/rev of load and 4000-4800 RPM. There are about 40 cells in your particular fine knock learning table (all different load/rpm ranges). When conditions dictate a change to fine knock learning and a knock event is perceived, it will decrease the value in the current cell by 1.4 deg. So, if, say, load was 2.0 g/rev and RPM was 4200, then we would be in the example cell above and it would decrement that cell by 1.4 deg (i.e. it would be -1.4). Then, any time load is between 1.87 and 2.43 g/rev and RPM is between 4000 and 4800 RPM, it will apply this correction of -1.4 (so a broader range than where the previous knock event occurred). When it perceives no knock in that cell (and other conditions are met), it will increment by a smaller value (0.35). In this example, it would go to -1.05, until eventually it will work its way back to zero over time.

So, when you see fine knock learning in your logs, it may not be current perceived knock, but the re-application of a past correction. Values outside of the 1.4 deg. decrements are values that have started to learn back to zero. You could even pass through multiple cells consecutively in the log that have some correction that is being applied.

Bill
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Old 04-23-2012, 08:27 PM   #7
Nu2SubaruWRX
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Bill-

Thank you for the fantastic responses; says a lot for COBB customer support. Now that we better understand that it is learned fine knock, the dots are starting to connect. When we made our first attempt at datalogging, my buddy did a 1st to 6k, then a 2nd to 6k and let off. Right after he shifted into second, the car bucked a bit in the 4k to 5k range...he isnt much of a shifter. It just felt like the clutch was grabbing or something, he wasnt smooth with it at all.

During this first run (the 1st to 2nd gear), I didnt know that I had to press the button again to datalog; I know, I'm a newb at this. We figured this out when we plugged in the AP. After doing some reading we found out that you have to press the button again. We went right back out after these failed datalogs to to record the ones I posted up in this thread.

Would it be possible that his awful shifting could have caused this learned fine knock? It was probably 10 minutes and less than 3 or 4 miles after his shift-fail that we took these 5 datalogs.

Thank you for all your help so far, it is much appreciated.
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Old 04-24-2012, 08:35 AM   #8
Cobb Tuning
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Bill-

Thank you for the fantastic responses; says a lot for COBB customer support. Now that we better understand that it is learned fine knock, the dots are starting to connect. When we made our first attempt at datalogging, my buddy did a 1st to 6k, then a 2nd to 6k and let off. Right after he shifted into second, the car bucked a bit in the 4k to 5k range...he isnt much of a shifter. It just felt like the clutch was grabbing or something, he wasnt smooth with it at all.

During this first run (the 1st to 2nd gear), I didnt know that I had to press the button again to datalog; I know, I'm a newb at this. We figured this out when we plugged in the AP. After doing some reading we found out that you have to press the button again. We went right back out after these failed datalogs to to record the ones I posted up in this thread.

Would it be possible that his awful shifting could have caused this learned fine knock? It was probably 10 minutes and less than 3 or 4 miles after his shift-fail that we took these 5 datalogs.

Thank you for all your help so far, it is much appreciated.
I imagine it would be possible. I would just do some more logging and see what you come up with, assuming you don't let your friend drive the car again.

Bill
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Old 04-27-2012, 05:34 PM   #9
Nu2SubaruWRX
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I imagine it would be possible. I would just do some more logging and see what you come up with, assuming you don't let your friend drive the car again.

Bill
Bill,

We did some datalogging today with the OTS Stage 1 91 map. As you will see, there is not any fine knock.

We both think it was that horrible shifting that got the learned knock to show up on the old datalogs. Would it be safe for him to go back to the 93 map and datalog it after another week of driving? Thank you for your help.

https://docs.google.com/spreadsheet/...F9qX25Dc0ZCdnc

https://docs.google.com/spreadsheet/...nZiZk1GUUFCd1E

https://docs.google.com/spreadsheet/...k1UNlN2b3VVU3c
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Old 04-28-2012, 07:57 AM   #10
Cobb Tuning
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Bill,

We did some datalogging today with the OTS Stage 1 91 map. As you will see, there is not any fine knock.

We both think it was that horrible shifting that got the learned knock to show up on the old datalogs. Would it be safe for him to go back to the 93 map and datalog it after another week of driving? Thank you for your help.

https://docs.google.com/spreadsheet/...F9qX25Dc0ZCdnc

https://docs.google.com/spreadsheet/...nZiZk1GUUFCd1E

https://docs.google.com/spreadsheet/...k1UNlN2b3VVU3c
Logs look good. I would stay on the 91 map for another week. Fine knock learning can take a bit of time to populate after you reset the ECU, which occurs when you reflash a map. Once you know that the more extreme fine knock learning is gone (some single counts, -1.4, of fine knock learning are usually normal), then I would try the 93 map again. But it is up to you - I don't think there's any concern with switching to the 93 map now.

Bill
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Old 06-26-2012, 08:40 PM   #11
Nu2SubaruWRX
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Well, my buddy has been on the 93 Normal Wastegate Stage 1 tune since my last post in this thread (2 months ago). We did some datalogging today to see what was going on.

https://docs.google.com/spreadsheet/...TdFbENQY3gtSWc

We think it looks normal, but we are no experts on the matter. There could be a major brain-fart hiding in that log. Hopefully not. Thank you for all of your help.
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Old 06-27-2012, 09:10 AM   #12
Cobb Tuning
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Well, my buddy has been on the 93 Normal Wastegate Stage 1 tune since my last post in this thread (2 months ago). We did some datalogging today to see what was going on.

https://docs.google.com/spreadsheet/...TdFbENQY3gtSWc

We think it looks normal, but we are no experts on the matter. There could be a major brain-fart hiding in that log. Hopefully not. Thank you for all of your help.
Log looks fine, but I would try to get a full 3rd gear run in there (if you can so safely).

Bill
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