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Old 08-30-2016, 06:11 AM   #26
RavensFan7
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Default Positive A/F learning, lots of FKLC

Sorry to keep bumping this. Forums are the only way of getting help on this annoying issue.

So, the fuel trims are back to being rather positive. I finally borrowed a new MAF sensor. It didn't really help with the fuel trims, but it almost made the FLKC go away.

Is that possible? For the MAF to help with knock but not the fuel trims? Seems backwards to me.

I put my MAF back in and it's right back to tons of FLKC like before. On the way to work today I was just cruising in 5th no boost, and the DAM dropped to .500 then back up to 1.000.
After that the FLKC didn't happen as often.

I'm just so confused.
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Last edited by RavensFan7; 08-30-2016 at 07:20 PM.
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Old 09-01-2016, 08:30 PM   #27
RavensFan7
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Replaced the FPR with a new OEM unit.

Didn't help the AF learning, but it got rid of all the FKLC.
...but now it shows all the knock under Feedback Knock instead. -2.00 to -8.00. Still happens right around 4,000 rpm.

Replaced the MAF after the FPR:
-The old MAF would only read a max of 167~ g/s.
-The new MAF already went up to 215 g/s (and that wasn't even WOT).

So it's reading better now, but it feels slower....like it hits a wall and doesn't pull as hard.

New MAF also made the AF learning leaner. The "c" value is already back up to +10%. Still no FKLC, just feedback knock.

What the hell?
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Old 09-01-2016, 09:25 PM   #28
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feedback knock is worse than fine knock learning. your car is getting worse, not better. i'd lay off the wot pulls until you figure out what's going on, or you're going to **** your engine.

so you burnt up an exhaust valve. replaced it, but never diagnosed WHY you burnt it up? i'm guessing your engine is running hot AF. one way to burn an exhaust valve is overheating the process, not allowing the exhuast gases to escape properly, they back up and everything gets overheated. OEM pipes and cats tend to have that effect. you know you have a cat in your uppipe, right? i don't know if that's your issue or not, you could install an EGT gauge to be sure. they usually tap the exhaust manifold right outside one of the cyclinders for them...

you're running a rich map, both cobb's and OEM maps are pretty rich, into the 10's easy. it's not a lean condition causing your knock.
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Old 09-02-2016, 05:41 AM   #29
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Default Positive A/F learning, lots of FKLC

Quote:
Originally Posted by hondaeater69 View Post
feedback knock is worse than fine knock learning. your car is getting worse, not better. i'd lay off the wot pulls until you figure out what's going on, or you're going to **** your engine.
I never ever go WOT. And as of this morning the FKLC is back. Don't know why it didn't show at all yesterday.

Quote:
Originally Posted by hondaeater69 View Post

so you burnt up an exhaust valve. replaced it, but never diagnosed WHY you burnt it up?
This whole thread is me trying to diagnose why the valve went bad.
Diagnosing why it went bad, and fixing this issue are one in the same. It's running exactly like it was before the valve went bad. I'm sure the same thing will happen again, or worse this time (piston).

Quote:
Originally Posted by hondaeater69 View Post
i'm guessing your engine is running hot AF. one way to burn an exhaust valve is overheating the process, not allowing the exhuast gases to escape properly, they back up and everything gets overheated. OEM pipes and cats tend to have that effect. you know you have a cat in your uppipe, right? i don't know if that's your issue or not, you could install an EGT gauge to be sure. they usually tap the exhaust manifold right outside one of the cyclinders for them...
I can read the factory egt with the accessport, for what it's worth. During cruise it's usually between 1200*F - 1350*F.....and under boost it'll quickly jump to 1500*F - 1600*F. I can't imagine the uppipe cat would be causing that. Otherwise lots of people's cars would be doing this, as well as my Impreza that makes more power/higher boost.

The high EGT's are probably because of the lean conditions. I know rich can cause high EGT's under certain conditions, but usually lean = higher EGT's, right?

Quote:
Originally Posted by hondaeater69 View Post

you're running a rich map, both cobb's and OEM maps are pretty rich, into the 10's easy. it's not a lean condition causing your knock.
I've always read the factory maps run kinda lean.....but either way, even if the maps are rich, I'm running lean regardless. The AF learning are still all positive.

Last edited by RavensFan7; 09-02-2016 at 07:46 AM.
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Old 09-02-2016, 03:51 PM   #30
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how exactly did you conclude you're running lean? without logging a wideband 02 sensor yo'ure guessing based on AF learning values. these don't mean rich or lean, just how much fuel is being added or taken away to try and hit it's targets. your af learning number %'s are low, so chances are you're hitting your AFR targets. and trust me, OEM and cobb maps are RICH. the only time OEM maps run lean is under the OL/CL fueling delay, outside that the fueling targets in the OEM maps are PIG RICH. i can assure you.

if you are running lean, it's not because of the mapping, it's due to something mechanical.
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Old 09-02-2016, 07:42 PM   #31
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I haven't read the whole thread, but have you investigated the oem injectors by having them flow tested/cleaned? I believe I've read about it being a somewhat common issue with burnt exhaust valves happening on the LGT's, and I think some of the speculation was the injectors being the issue.

I also believe(I'd have to go check again) that the stock tune of some year Legacy's add extra ignition timing in cylinder 4 which is probably contributing to the issue also.
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Old 09-02-2016, 08:37 PM   #32
RavensFan7
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Default Positive A/F learning, lots of FKLC

Quote:
Originally Posted by hondaeater69 View Post
how exactly did you conclude you're running lean? without logging a wideband 02 sensor yo'ure guessing based on AF learning values. these don't mean rich or lean, just how much fuel is being added or taken away to try and hit it's targets. your af learning number %'s are low, so chances are you're hitting your AFR targets. and trust me, OEM and cobb maps are RICH. the only time OEM maps run lean is under the OL/CL fueling delay, outside that the fueling targets in the OEM maps are PIG RICH. i can assure you.

if you are running lean, it's not because of the mapping, it's due to something mechanical.

True, without a wideband I can't be sure. But the AF learning has always be positive. Doesn't that tell me something isn't right if it's always adding fuel? Right now it's at 12.5% for C and atleast 6% for the others.

I don't think the maps are causing me to run lean. I agree it's mechanical. That's partly why I posted in the tuning section, so I could post logs and maybe someone could spot something I didn't see....or suggest something else to check. Cause I've checked pretty much everything

I didn't mean the factory map was super lean or anything, just from what I've always read the Cobb maps are a bit richer than the factory maps. Not saying either are extremely lean or rich, just slightly different from each other.



Quote:
Originally Posted by SkateAndDestroy View Post
I haven't read the whole thread, but have you investigated the oem injectors by having them flow tested/cleaned? I believe I've read about it being a somewhat common issue with burnt exhaust valves happening on the LGT's, and I think some of the speculation was the injectors being the issue.

I also believe(I'd have to go check again) that the stock tune of some year Legacy's add extra ignition timing in cylinder 4 which is probably contributing to the issue also.

The injectors were all cleaned and tested around the time of the valve replacement. So they should still be good.

That extra timing in cylinder 4 thing makes me VERY curious though.....especially since the valve that was burned was cylinder 4.

I'll go read up on that and try to find it too. If you find the link post here or pm me. I've done a lot of reading on legacygt.com and specific legacy posts and haven't heard that yet. The LGT is a weird car though, so it's definitely possible.

Last edited by RavensFan7; 09-02-2016 at 08:47 PM.
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Old 09-03-2016, 12:19 AM   #33
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you get into the 11's pretty fast, and max the stock sensor out at 10#'s of boost. do you have logs of when the feedback knock occurs? small amounts of FKL isn't anything to get excited about, but your afr's in those logs look rich to me. and your ecu is trying to add another 10% on top of that! fueling at that point is only added for cooling purposes, it doesn't make more power, it's only for protection.
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Old 09-07-2016, 05:29 AM   #34
RavensFan7
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Default Positive A/F learning, lots of FKLC

Quote:
Originally Posted by hondaeater69 View Post
you get into the 11's pretty fast, and max the stock sensor out at 10#'s of boost. do you have logs of when the feedback knock occurs? small amounts of FKL isn't anything to get excited about, but your afr's in those logs look rich to me. and your ecu is trying to add another 10% on top of that! fueling at that point is only added for cooling purposes, it doesn't make more power, it's only for protection.

Since it's just the factory front 02 I don't pay much attention to the AF ratio under boost.

I'll get some logs of the feedback knock soon...but it happens anytime. Just getting up to speed without boost, under full boost, and sometimes it won't happen at all under full boost.

I have to look everything over again. The AF learning are changing up a lot for some reason. Now the D trim is slowly going negative day by day....and the rest are well over 8% positive. The C trim jumps around from 11%-15% positive. Currently they are:

A +11%
B +10.20%
C +12.40% (11-15%)
D -2.50%

Last edited by RavensFan7; 09-07-2016 at 06:00 AM.
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