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Time to identify once and for all the source of my FKC


xt2005bonbon
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Back in 2011 (~50k ago), I noticed while going up a steep hill at fairly low load/2-3k rpm what appeared to sound like rod knock or something. At that time, I did not own any tool to log and stuff.

In 2012, I learned how to use Romraider and got a stage 1 tune. I did notice a consistent FKC event which at times turned to an FLKC cell of around -6 degrees at low load/2-3k rpm.

Fast forward now (99k) and that knock has ever been present :mad:. It is getting super annoying as it affects performance. Here is one video of it where the knock sensor hears knock. But I did this one at idle with clutch off the flywheel.

 

I want to get to the bottom of this now. It is time! So whenever I find more clues and stuff, I will update this thread. It may turn to a #YNANSB thread! :lol:

 

[ame=http://www.youtube.com/watch?v=bMdk1iFxTcI]annoying low load knock--subaru outback 05 xt - YouTube[/ame]

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I have a similar rpm location FK. Mine mainly seems to exist in overdrive or high gear at that rpm (2300-2800).

 

I have removed all heat shields and made sure of no rattles. I almost wonder if motor mounts are aging and allowing just a perfect vibration or resonance off mounts... I am in an e tune process hoping to get it sorted. I had low compression (off 20psi) on a cylinder, but the car has no other knock or oil burning... fruity pebbles.

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I made sure that I do not have anything rattling and stuff like that. Unfortunately, at times I can actually hear some type of 'knocking' sound at the above mentioned rpm/load range. You just have to hit the right amount of throttle and stay there and you may hear it a bit. I will try to capture that in a video hopefully soon.

 

In any case if it was indeed rod knock, I would think the engine would have seized by now!

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Yep that is it. Nexus 7 2013 with the Timur ROM. I have the Btssm app, back up cam, usb DAC, usb thumb drive all hooked up to it. And got the steering wheel controls hooked up too and customized to open specific apps (e.g. google map, google play, btssm, etc..) :cool:.

 

Am about to repeat that exact same install in my 06.

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Yep that is it. Nexus 7 2013 with the Timur ROM. I have the Btssm app, back up cam, usb DAC, usb thumb drive all hooked up to it. And got the steering wheel controls hooked up too and customized to open specific apps (e.g. google map, google play, btssm, etc..) :cool:.

 

Am about to repeat that exact same install in my 06.

 

Man! I do not need new project(s)!!! (too many cars, not enough time) :spin:

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I know this might be long shot but do you still have the plastic engine cover? I had an event a while back where it got unusual high knock in the mid 2K's, and actually continued at idle. I popped the hood and I could hear the plastic cover rapping on the intake manifold. Mind you I altered the cover due to a upgraded TMIC, but I was quite surprised
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I get the same exact issue when free reving, clutch engaged or not. At this point I'm convinced it's just engine noise, and free reving just gets you outside of the FBKC blind zones.

 

Now if your hearing auditable knock, there is probably something wrong, ie not enough octane or too much timing.

 

Is your tune a pro tune or DIY? If DIY wanna send me a copy, I can review it for you.

 

 

I want to know more about your display/carputer! (been out of the loop)

 

EDIT: I guess this is this: http://legacygt.com/forums/showthread.php/btssm-bluetooth-adapter-app-229709.html

 

Dammit I want it now too :lol:

05 LGT 16G 14psi 290whp/30mpg

12 OBP Stock 130whp/27mpg@87 Oct

00 G20t GT28r 10psi 250whp/36mpg

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I get the same exact issue when free reving, clutch engaged or not. At this point I'm convinced it's just engine noise, and free reving just gets you outside of the FBKC blind zones.

 

Now if your hearing auditable knock, there is probably something wrong, ie not enough octane or too much timing.

 

Is your tune a pro tune or DIY? If DIY wanna send me a copy, I can review it for you.

 

 

 

 

Dammit I want it now too :lol:

 

 

It is an open tune. I'd love you to check it out and see if you notice anything wrong. I have no problem with it.

 

Regarding the tablet setup, I can send you the list of stuff that I bought. It actually is not that expensive at all. Ebay ftw.

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That behavior looks very strange to me... I'm not sure about the '05 ROMs, but on my '07, if it detects any knock at all, as soon as I'm off the throttle FBKC and FLKC will decay to zero instantly.

 

That said, I typically see similar knock profiles at low RPM, and I agree with covertrussian. At low RPM, the knock sensor is going to hear a bunch. There's tons of tables that allow you to modify how sensitive the sensor is, but I wouldn't mess with them unless you're really sure of yourself (which I'm not).

 

Watch the knock-sum on the following video... since I'm under the FBKC threshold, I don't get any pulled timing, but the knock sensor is "hearing" quite a bit of knock at idle. Some of it is likely A/C compressor, some of it is clutch engaging/disengaging, but to me it looks like the majority is just engine noise at low engine speeds.

 

[ame=http://www.youtube.com/watch?v=NCYsgitLaV4]Knock knock! - YouTube[/ame]

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Video is not allowed in USA, contains content from SME?

 

:lol: :lol:

 

Had music playing in the background which YT picked up as copyright infringement, but of course it doesn't make it obvious to me since I'm logged in to my account and it plays fine. Should be fixed in a couple minutes (removed audio from the video).

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What kinda mods do you have? Any mounts, braces, or dampeners?

 

I had a loose timing belt tensioner that would rattle when rpms reached about 2800-3000.

 

Also, when I installed my billet pitch stop without the group N engine mounts every other little rattle was amplified. Just saying that it might be worth looking at the condition of the mounts if they're the originals.

 

 

Sent from my iPhone using Tapatalk

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:lol: :lol:

 

Had music playing in the background which YT picked up as copyright infringement, but of course it doesn't make it obvious to me since I'm logged in to my account and it plays fine. Should be fixed in a couple minutes (removed audio from the video).

 

Finally a Canadian can see a vid an American can't :lol::lol: WE usually get the shaft hahaha

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That behavior looks very strange to me... I'm not sure about the '05 ROMs, but on my '07, if it detects any knock at all, as soon as I'm off the throttle FBKC and FLKC will decay to zero instantly.

 

At times, it quickly goes back to zero. But other times, it does it as shown in the video. Yeah, strange. I will include the knock sum cause maybe as the FLKC value was going back to zero, it heard additional knock and therefore slowed down its decay rate? :confused:

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What kinda mods do you have? Any mounts, braces, or dampeners?

 

I had a loose timing belt tensioner that would rattle when rpms reached about 2800-3000.

 

Also, when I installed my billet pitch stop without the group N engine mounts every other little rattle was amplified. Just saying that it might be worth looking at the condition of the mounts if they're the originals.

 

 

Sent from my iPhone using Tapatalk

 

Not much really. K&N panel filter, catless up pipe, HF Invidia catted DP and that is it really. I recently reinstalled all the exhaust system with new gaskets and made super sure the shields don't rattle.

 

Regarding the engine mounts though, I never touched them.

 

I need to have my wife be in the driver seat, keep the engine revving at a specific rpm and I will stare at the engine bay. I still have not had a chance to do that..

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Thanks for reminding me :lol:. Sigh. Just hard to take care of family stuff, work stuff, other stuff, and of course subaru stuff :rolleyes:

 

In the end, I would like to achieve a smooth timing table just like yours but still going 18 psi or so. I need to take a look.

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  • 2 weeks later...
I think before I will further modify the tune, I need to perform an oil sample analysis. I have a feeling I either have a ringland issue or something else going on internally. Not only she knocks in low loads, but she loves oil a bit too much. And I am getting pretty crappy gas mileage now (went on a 2hr road trip with the family--slightly hilly freeway at times----went 75-80mph on average--- 18.6 mpg!). The 06 would probably do like 24 mpg for the same stretch of road and with the same load in the car. Something is up.
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