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Old 09-26-2023, 07:16 PM   #1
Scooby Newbie
Member#: 535629
Join Date: Sep 2023
2015 STI

Talking FeedBack Knock

Hey Guys,

First post here!

I was looking for someone that can diagnosis and read the logs from my AP. I have a 2015 STI, I spun a rod bearing awhile back and replaced the motor with a Type RA shortblock. I am having trouble diagnosing an issue regarding the knock detection.

I commute 2 hours to work and back once a week. On my trip to work, i do not have any feedback knock. The car sits for 8 hours prior to returning home. I start registering feedback knock on the way home after about 1 hour of driving. The knock instances occur when i hit a little boost and it retards timing. (I have not tried to go WOT when the knock registers to avoid any damage if something is wrong) I did notice it occurs when my oil temp is between 200-220F. Eventually my DAM will drop to .928. The Dam will reset to 1 eventually. The next day when i drive it, i do not get any knock instances on WOT or light load conditions. I attached some logs in hopes someone can give me some insight on what to look for. I have switched to 5W-40 to help negate piston slap. I thought about switching back to 5W-30 to see if that helps. I have already checked the Knock sensor, checked to see if anything was loose or could be causing phantom knock. I think it may be phantom knock, but am unsure.

Here is the link for the datalogs:

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Old 11-02-2023, 02:21 PM   #2
Scooby Newbie
Member#: 535999
Join Date: Nov 2023

I would send your concern and datalog to Cobb and ask them to evaluate and provide a recommendation. I bought my 2019 STI new and put the Cobb AP and SF intake with a stage 1+ tune and I would sometimes see feedback knock up to 11% and fine knock learn around the same. This was at cruising highway speeds. I decided to get my car pro-tuned (E-tuned) and since then I don't see the feedback knock go over 2.8%. However, I do see the fine knock learn jump up to 7% sometimes. I'm considering putting the stock intake back on and flash the car back to the OEM tune. The performance gain is not worth it, neither is the whoooosh noise. My car just hit 17k miles and I plan on keeping it for the long run.
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Old 11-27-2023, 09:14 PM   #3
Scooby Newbie
Member#: 536220
Join Date: Nov 2023

My DAM dropped while climbing a mountain lugging the engine. Maybe something similar since it doesn’t do it one way but does the other? I typically use 5th for highway speeds to about 75 mph or so. Also, bad gas can cause it.
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