Feedback Knock & Fine Knock Learn Question

Hi everyone,

 

 

I'm very new to the tuning world and don't know too much, if anything about it. Slowing learning about it. I have an 2006 Subaru Legacy GT and started logging recently as I noticed some feedback knock & Fine Knock learn values going weird and very high (-12). It seems like these only happen at low load. The car is stock except for exhaust and oem sti catless uppipe.

 

 

I have logged the attached, not too sure if I even logged it correctly lol but any insight is much appreciated

datalog5.csv

datalog6.csv

Edited June 9, 2019 by Rain

I see what you see - large learned timing pulls only at low load, and none under load. I see similar "false knock" FBKC adjustments as in the end of your first log, but almost always at 2.11 degrees or less.

 

There must have been some event, real or otherwise, that caused the timing adjustment under load load that you're seeing the ECU applying now. Since that's a range you probably drive in pretty often, I'd watch it for a while and see if it tapers back down. You could also reset the ECU and see if it learns its way back up, but that's a less safe option IMO. I'd check for things rattling in the engine bay as a first step. Check for vacuum leaks as well, it's possible you're leaning out in vacuum and knocking as a result. I'd think if you had a leak bad enough to have caused that much timing pull you'd feel it by way of rough running/idle, but could be wrong. After all that I'd consider replacing the knock sensor. Not usually a fan of 'guess and check' part replacement, but it's a cheap part.

Thank you, really appreciate the help. Will check for rattling in the engine bay and for any leaks. Also whats really weird is that I took it out for a drive again the other day; during city driving only, I probably only had -2 feedback knock max. However, it's when I get off the highway, and going back to city driving, I see these large timing being pulled. Don't know if anyone has experienced this, it's really weird.