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Old 05-26-2016, 05:42 AM   #1
RavensFan7
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Default Positive A/F learning, lots of FKLC

So my 06 Legacy GT (5mt) has always had positive fuel learning and very odd FKLC since I got it. Completely stock besides a catback and Accessport 93 map. I was about to get a pro-tune before all these problems happened.....believe me I don't like the OTS Cobb map either.

After a couple months of owning it, things got worse and I realized it developed a bad exhaust valve in cylinder 4.

Picture of valve:



So the valve was replaced, other hoses and such were replaced while it was apart. Runs great now......vacuum is nearly perfect at idle, and will boost just fine.

.....but the A/F learning is still very positive and still has tons of FKLC. Just like it was before the valve was replaced.

AF learning 1 is currently:
A= +4%-8%
B= +2%
C= +9%-11%
D= +11%-12%

The FKLC will show anywhere from -1.xx to -7.xx. Doesn't really happen at full/high boost, but will almost always happens at medium load or low-ish boost levels. Sometimes it will climb with RPM's and won't stop until I let off the throttle.....again, this is NOT full boost. The DAM only dropped once, and that's was from 1.000 to 0.750 but went back up instantly.


I can upload some logs later today. Just not sure where to keep looking for problems. I've double, and triple checked everything and can't find any obvious issues.
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Old 05-26-2016, 05:36 PM   #2
Yannysti2011
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Send some logs to cobb support. They really help me when i got some problems in the past. It look like you running lean ... I suggest to reflash a 91 map but keep running 93 or 94 gas to see if the fine Knock learn correction are better. Do you see some FBKC or only FKLC ? Also the thresold for A/F ratio should be within +/- 8% max so it's definitly something you should investiguate more. Try to post some logs in here . It's maybe not a good idea to do WOT logs for now .
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Old 05-26-2016, 08:50 PM   #3
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Here's 2 logs. Sorry for the lack of parameters.....I thought I had more selected, but they didn't show up. A bunch of the main ones are still in the log, so I'll post these for now and get better ones tomorrow or Saturday.

Although it's one of the parameters that didn't get logged, the DAM stayed at 1.00 the whole time, for both logs.

First one shows some of the low/medium load FKLC, and also has a 4th gear 'pull' at about 70% throttle (starting near cell 450).

https://docs.google.com/spreadsheets...it?usp=sharing

Second one just shows more low/medium load FKLC.

https://docs.google.com/spreadsheets...it?usp=sharing

Last edited by RavensFan7; 05-26-2016 at 09:09 PM.
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Old 05-26-2016, 10:42 PM   #4
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You running pretty lean.Do you have a intake that fit with the map? Maybe leak arround the intake,dirty filter? dirty sensor? When you're going easy on the throttle and cruising in high gear, both the cobb mapping and stock Subaru mapping will have you 'riding the knock sensor', or in other words, leaning out the AFR and adjusting timing to be as efficient as possible. When knock is noticed, either timing will be pulled or the AFR will be enriched to eliminate this knock.
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Old 05-26-2016, 11:31 PM   #5
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Borrow a MAF sensor from another LGT and check fuel trims.
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Old 05-27-2016, 05:51 AM   #6
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Default Positive A/F learning, lots of FKLC

Quote:
Originally Posted by Yannysti2011 View Post
You running pretty lean.Do you have a intake that fit with the map? Maybe leak arround the intake,dirty filter? dirty sensor? .

No, the only intake I have is the OEM one.

I'll pull off the MAF and check the o-ring and sensor when I get home. Filter is good. I could also try the carb cleaner method again, and maybe even do a smoke test.

It does seem like it's a pre-turbo, post MAF vacuum leak. I just don't think it really is. I've checked all the hoses (also tried the carb cleaner) and vacuum is pretty much perfect.

-9.5 psi, or -19.3 inhg at idle fully warmed up.


Quote:
Originally Posted by Airboy View Post
Borrow a MAF sensor from another LGT and check fuel trims.

I only know one other person with a Subaru, and it's a bugeye WRX. Even then, my other car is a WRX swapped Impreza, so I have the same parts laying around the house.

Not many parts are the same between the LGT's ej255 and WRX's Ej205 either. I cross referenced the MAF's and they are different.
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Old 06-24-2016, 05:38 AM   #7
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Default Positive A/F learning, lots of FKLC

Ok, I did some stuff, and got some changes.

--The 91 map (while running 93), and "stock parameter map" didn't make much of a difference on their own.

--So I went back to basics and did all the airbox stuff....
-new air filter
-cleaned MAF (was dirty)
-tightened the sensor down better

The MAF wasn't fully tight, probably from the idiots that did warranty work recently. I think that had a lot to do with it.

I'm at 1000 miles after the last ecu reset, and the fuel trims are MUCH better....although they're still changing as I drive.

--So here's the current fuel trim numbers....the only problem is that I'm still running the 91 map while using the 93 gas. I forgot to switch back to the 93 map after the airbox stuff.

Yesterday when I got home:
A: -6.00%
B: -6.50%
C: +1.30%
D: +3.60%


This morning after a 40 min drive to work:
A: -7.30%
B: -6.50%
C: -0.40%
D: +2.60%


As you can see the trims for C and D are much closer to 0% now. A and B are pretty rich, probably from the 91 map, but better than being lean.

Should I go back to the 93 map?

Last edited by RavensFan7; 06-24-2016 at 05:48 AM.
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Old 06-24-2016, 10:46 AM   #8
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Those trims are good, anything less than +/-8 is gold!

On my car I always use 93 gas and if I'm using OTS maps always the 91 maps, the 93 just knocks too much.
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Old 06-24-2016, 11:51 AM   #9
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Default Positive A/F learning, lots of FKLC

Yeah, I'm happy with the trims for sure. I always use 93, and would like to get a real tune once all this is straightened out.

But the FKLC hasn't gotten much better, if not worse. I try to stay out of higher boost, except for getting a log.

I want to think it's false knock, but it does happen over 1.0 load, and happens a lot, so I'm not sure.

Usually, if I see the FKLC at like -1.40 while cruising, I can jab the throttle and the FKLC goes to 0.00 instantly.....but sometimes it doesn't.

Here's a log:

I'm too scared to do a WOT pull, so here's a 50% or so pull. It usually doesn't show any FKLC above 5 psi, but this log shows it around 10 psi or so....which I really don't like.

The long knock event starts around 28 seconds. You can see once I let off the throttle it still shows -1.4 for a few seconds.

https://docs.google.com/spreadsheets...fh6F7fm70Fz3OY


Edit:

Just drove about 40 minutes home from work, and the was no FKLC at all. None.

So weird. Sometimes it happens a lot, sometimes it doesn't.

Last edited by RavensFan7; 06-24-2016 at 02:40 PM.
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Old 06-25-2016, 12:12 AM   #10
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Try setting the map to run wastegate boost after you flash if you decide to flash it reset the ecu. Drive like you regularly would for 100 miles see how it is.
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Old 07-14-2016, 09:07 AM   #11
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Quote:
Originally Posted by crosswound View Post
Try setting the map to run wastegate boost after you flash if you decide to flash it reset the ecu. Drive like you regularly would for 100 miles see how it is.

What would this do? Not trying to question your advice, but I just like to understand what I'm doing.

I don't have to be in boost for the FKLC to start acting up.

Lately the FKLC has still been doing the same stuff. I've been trying to stay out of boost as much as possible.

It's weird, if I keep it under 3500 RPM, under 50% throttle, and low-ish load, the FKLC will stay 0.00 for a whole drive.....but it seems like as soon as I go above a certain RPM or load, the FKLC starts being weird. It'll show between shifts, randomly during cruising, randomly during deceleration.

Just weird.
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Old 07-14-2016, 02:26 PM   #12
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Quote:
Originally Posted by RavensFan7 View Post
Yeah, I'm happy with the trims for sure. I always use 93, and would like to get a real tune once all this is straightened out.

But the FKLC hasn't gotten much better, if not worse. I try to stay out of higher boost, except for getting a log.

I want to think it's false knock, but it does happen over 1.0 load, and happens a lot, so I'm not sure.

Usually, if I see the FKLC at like -1.40 while cruising, I can jab the throttle and the FKLC goes to 0.00 instantly.....but sometimes it doesn't.

Here's a log:

I'm too scared to do a WOT pull, so here's a 50% or so pull. It usually doesn't show any FKLC above 5 psi, but this log shows it around 10 psi or so....which I really don't like.

The long knock event starts around 28 seconds. You can see once I let off the throttle it still shows -1.4 for a few seconds.

https://docs.google.com/spreadsheets...fh6F7fm70Fz3OY


Edit:

Just drove about 40 minutes home from work, and the was no FKLC at all. None.

So weird. Sometimes it happens a lot, sometimes it doesn't.
Is the knock happening on the same table column and rpm? If so then you have real knock. Otherwise you might be chasing ghost knock.
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Old 07-14-2016, 05:57 PM   #13
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Quote:
Originally Posted by Gab0 View Post
Is the knock happening on the same table column and rpm?

Not exactly sure what you mean here, but I checked a bunch of different logs.

There is re-occurring FKLC right at 4,000 rpm.....between 3,990 - 4,030. Happens on a few different logs.
But there's also knock at other rpm/load/ect, anywhere from 2,000 rpm to 5,000 rpm.
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Old 07-14-2016, 06:05 PM   #14
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Quote:
Originally Posted by RavensFan7 View Post
Not exactly sure what you mean here, but I checked a bunch of different logs.

There is re-occurring FKLC right at 4,000 rpm.....between 3,990 - 4,030. Happens on a few different logs.
But there's also knock at other rpm/load/ect, anywhere from 2,000 rpm to 5,000 rpm.
"There is re-occurring FKLC right at 4,000 rpm.....between 3,990 - 4,030"
The statement you made above tells me that is real knock because it continues to happen in the same "spot" throughout multiple logs. Ghost knock on the other hand will never take place in the same "spot". I would remove two degrees of ignition in that spot and see if that gets rid of the knock event. Also what is your A/F ratio at that particular RPM?
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Old 07-18-2016, 10:55 AM   #15
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Default Positive A/F learning, lots of FKLC

Quote:
Originally Posted by Gab0 View Post
"There is re-occurring FKLC right at 4,000 rpm.....between 3,990 - 4,030"

The statement you made above tells me that is real knock because it continues to happen in the same "spot" throughout multiple logs. Ghost knock on the other hand will never take place in the same "spot". I would remove two degrees of ignition in that spot and see if that gets rid of the knock event. Also what is your A/F ratio at that particular RPM?

It starts at exactly 4,000 rpm, but doesn't just start then stop. It'll happen for 5, 10, 20 seconds, if not more. It'll just keep showing FKLC as the rpm climbs past 4,000 rpm......anywhere from -1.4 to -6.xx.

I don't see how the current map would be the issue. It did the same thing with the factory map, Cobb "stock mode" map, Cobb 93 map, and Cobb 91 map. I think Cobb got rid of ATR, so I'm not sure if I could even mess with the tuning myself (not that I would want to).

I tested it more, and pretty much every time I get to exactly 4,000 rpm the FKLC goes crazy. There's still some random FKLC below 4,000 but it happens much less. I can get into boost heavily below 4,000 rpm and no knock at all.
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Old 07-18-2016, 11:27 PM   #16
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Check up pipe heat shield. Really be nice to see a wot pull.
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Old 07-20-2016, 12:45 PM   #17
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Default Positive A/F learning, lots of FKLC

Quote:
Originally Posted by Joshfl420 View Post
Check up pipe heat shield. Really be nice to see a wot pull.

Just did a quick check and no noticeable rattles or anything. I also checked over the heat shields really well when I had the engine out a few months ago. Up pipe head shield is definitely solid.

I'd like to try a WOT pull for log purposes as well, but it just seems like a bad idea. With the ecu showing/thinking there's tons of FKLC at mid-RPM and mid-boost, I'm scared to see what happens under full load.
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Old 07-20-2016, 05:12 PM   #18
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Quote:
Originally Posted by RavensFan7 View Post
It starts at exactly 4,000 rpm, but doesn't just start then stop. It'll happen for 5, 10, 20 seconds, if not more. It'll just keep showing FKLC as the rpm climbs past 4,000 rpm......anywhere from -1.4 to -6.xx.

I don't see how the current map would be the issue. It did the same thing with the factory map, Cobb "stock mode" map, Cobb 93 map, and Cobb 91 map. I think Cobb got rid of ATR, so I'm not sure if I could even mess with the tuning myself (not that I would want to).

I tested it more, and pretty much every time I get to exactly 4,000 rpm the FKLC goes crazy. There's still some random FKLC below 4,000 but it happens much less. I can get into boost heavily below 4,000 rpm and no knock at all.
Every car is different, the fact you are running a Cobb "off the shelf" map does not equal a tune suited to your car. Cobb maps are meant to work with a variety of vehicles and fuel qualities. You are definitely experiencing knock. I made the assumption you were on a custom map. Hence my suggestion to remove two degrees of timing. Regardless as you stated ATR is no longer available and unless you know what you are doing I would suggest leaving it alone.

Last edited by Gab0; 07-20-2016 at 09:39 PM.
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Old 07-20-2016, 08:16 PM   #19
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If she blows under WOT she was gonna blow anyways IMO.
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Old 07-21-2016, 09:12 AM   #20
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Default Positive A/F learning, lots of FKLC

Quote:
Originally Posted by Gab0 View Post
Every car is different, the fact you are running a Cobb "off the shelf" map does not equal a tune suited to your car. Cobb maps are meant to work with a variety of vehicles and fuel qualities. You are definitely experiencing knock. I made the assumption you were on a custom map. Hence my suggestion to remove two degrees of timing. Regardless as you stated ATR is no longer available and unless you know what you are doing I would suggest leaving it alone.
Yea I know....I don't like using the OTS maps, but with all the problems I've had with the car I haven't been able to get a protune yet. My Impreza has a good protune and never shows any knock.

Quote:
Originally Posted by Gab0 View Post
You are definitely experiencing knock.
Basically this is what I wanted to know. It was very hard to tell if it was false knock or real knock. I have a decent understanding of logs/parameters, but it's always nice to have more sets of eyes look at the logs.

I figured the positive fuel trims (running lean) and FKLC were related, but apparently not.


Quote:
Originally Posted by Joshfl420 View Post
If she blows under WOT she was gonna blow anyways IMO.

Yea, but no sense in blowing it up any sooner
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Old 07-29-2016, 03:14 PM   #21
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Default Positive A/F learning, lots of FKLC

So how should I go about getting rid of this knock?

Getting a protune just doesn't seem like the right way.....I feel like there's some real mechanical issue, or leak, or something. It just doesn't make sense that a 100% stock car (besides catback) would NEED a tune so it doesn't knock.

To rule out the Cobb map being the issue I switched back to the "installed stock mode" map....which is supposed to have factory parameters. I've always read that Subaru's factory maps run kinda lean, but I'm not running lean. I'm actually on the richer side now (negative trims). The knock would make more sense if it was lean.

(I was also running rich when I was still on the Cobb 91 map)

A: -12.3%
B: -11.3%
C: -7.3%
D: -2.8%

Just doesn't make sense that the knock would happen the SAME EXACT way on different maps, while running super lean, and now running kinda rich.
Also the whole thing with it showing FKLC at 4K RPM every time is weird. It happens with pretty much no load (still in vacuum), or under boost.

Last edited by RavensFan7; 07-29-2016 at 03:30 PM.
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Old 08-17-2016, 07:48 AM   #22
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Default Positive A/F learning, lots of FKLC

One thing I forgot to mention.....the ONLY non stock part besides the catback.....is the clutch and flywheel.

I got rid of the dual mass flywheel stuff the LGT comes with, and installed the 06+ WRX single mass flywheel and clutch stuff. I've heard of random misfire codes with different flywheels, but not knock. So I doubt that's my problem, but I figured I would mention it.

Also, the C and D fuel trims went back to being slightly lean again (4% and 6% currently). They were rich a week ago. That's with both maps....the factory map, and Cobb 91 map running 93 octane.

I just don't understand why a car that's 97% stock would have so many problems with knock. I'm running out of patience.

Last edited by RavensFan7; 08-17-2016 at 09:11 AM.
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Old 08-21-2016, 06:32 PM   #23
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I had similar issues with all fuel trims being positive (+7.x - +10.x) , was informed the car had low fuel pressure at idle so I had a new FPR installed and now my trims are all slightly rich and well within spec for the Cobb OTS maps.

Food for thought.
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Old 08-22-2016, 07:07 AM   #24
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Default Positive A/F learning, lots of FKLC

Quote:
Originally Posted by Cobrakai View Post
I had similar issues with all fuel trims being positive (+7.x - +10.x) , was informed the car had low fuel pressure at idle so I had a new FPR installed and now my trims are all slightly rich and well within spec for the Cobb OTS maps.

Food for thought.

I guess the FPR could be a possibility, but all my fuel trims are within spec now. It just won't stop knocking.

I actually had the DAM drop from 1.000 to 0.750 once this weekend. It was only a mild pull to like 5k.....then it was fine the rest of the weekend.

Last edited by RavensFan7; 08-22-2016 at 09:33 AM.
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Old 08-25-2016, 04:14 PM   #25
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I noticed a trend in all the fuel trim numbers I posted: Richer at idle, leaner under load/boost.

When it was running SUPER lean in all the trims (a,b,c,d), the A and B trims were still richer than C and D.

Even currently, the A and B trims are slightly rich, but C and D are kinda lean.
A -3.00
B -2.00
C +3.00
D +5.50


What does that mean? What else can I check? This car is driving me crazy.

It makes me think the FPR, but all the reading I did on bad FPR's for legacy gt's, people were having trouble starting their cars. I've never had any starting issues.
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