Having low load knocking, should I be highly concerned?

[DeltaSniper]

After looking over the datalog I took yesterday it seems that I have some low rpm knock but none in a WOT high rpm scenario?

 

After searching up a bit this also could be false knock, but how can I tell?

 

Sorry I am a newbie at this!

 

https://docs.google.com/spreadsheet/ccc?key=0Anfmz5R-VyEMdHRsUlFnal92TkJTUFBvLXl2eUZaeVE#gid=0

 

It would be great if someone could chime in and give me an opinion on how this datalog looks.

[rob-2]

I am not sure what to tell you. My understanding on low load knock is from running too lean, if everything else like plugs are fine.

 

Injectors and oil in the burn are the two most common problems. Can you rule both of those out?

[fahr_side]

Very common on these cars, which run extremely high timing in low load / low rpm areas. I don't like it but Subaru sure don't seem to mind.

I usually drop timing in these areas a few degrees and get much better driveability and steadier IAM.

[eckseleven]

Ever since my car was pro-tuned, I've been keeping an eye on things. I don't think I've ever seen any feedback knock on a real pull (aside from the abrupt throttle change issue) but I do see it somewhat regularly in day to day casual cruising. I too have been concerned, but from what I've read, you can pretty much ignore the low values like -1.4 as long as you are at low RPM and low load (below 1.0 I think?).

 

I'm mostly a newbie when it comes to tuning these cars, but I don't think having a pro or e-tune is going to be any better than OTS in terms of cruising knock. If anything, it would seem these tunes could potentially knock more than OTS maps at low RPM since more timing is typically added early on. With my tune, the timing is quite aggressive which results in amazing throttle response and near zero turbo lag, but I can barely climb even a minor hill in 6th gear without seeing some knock. A strong gust of wind head-on can even do it. My issues (maybe they're not anything to really worry about) probably stem from me actually asking my tuner for an "aggressive" tune. I'll likely ask for something conservative next time I go.

 

I think the Cobb maps make their power by focusing on boost and not as much on timing. They sacrifice some low end response by doing this but it is probably safest since these maps run on cars that see a variety of atmospheric conditions and fuels.

 

So I don't know if any of that helps or not... And don't take some of these things as fact until someone like fahr_side or one of the other experts confirms

 

Out of curiosity, what kind of driving was this? Highway? Town? A lot of these knock situations in your log don't look like anything serious, but some seem strange to me. Like the one the ones that are -2.8 when RPM is below 2000. Or the -4.2. Maybe that's just noise or something.

[DeltaSniper]

Just datalogged my commute today and I see more strange things....

 

More higher knock values (-5.25) but still at low load scenarios (throttle at 15-20%)

 

Heck, this log even has a 3rd gear pull from 1700 rpm to redline and theres zero knocking at all, but low load knock is still there...

 

As per a tuners advise, he wanted to see more data parameters like Manifold Absolute Pressure, and that seems to coincide with the low load knocking I see? (speculation)

 

I don't know how that value is generated so I don't even know how this happens since I am a total newbie at this...

 

https://docs.google.com/spreadsheet/ccc?key=0Anfmz5R-VyEMdGJjS00xVnNVT3VtSTNMTXhUYWpYblE#gid=0

 

When I do get my car protuned, my priorities are "knock free (conservatism), fuel economy and power" in that order if that makes any sense.... I want to take care of this car since I plan on keeping it for a very very long time.

[fahr_side]

The Cobb OTS maps are junk. Free maps are worth exactly what you paid for them.