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*** Knock, do you have any?


LittleBlueGT

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Hey there birdmayne. Overall looks OK, not perfect. (FYI I do not claim to be an expert as it's been a little while since I have closely monitored my own tune)

 

I'm sure you'll get the speech about stock tune issues, but in general it looks like you don't have any fine learning correction, however you're getting some amount of FBKC at high load. Only single counts, which could be false knock, but worth keeping an eye on since it's at high load which is never good. Do you have a pull on different terrain such as flat / hill?

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Hey there birdmayne. Overall looks OK, not perfect. (FYI I do not claim to be an expert as it's been a little while since I have closely monitored my own tune)

 

I'm sure you'll get the speech about stock tune issues, but in general it looks like you don't have any fine learning correction, however you're getting some amount of FBKC at high load. Only single counts, which could be false knock, but worth keeping an eye on since it's at high load which is never good. Do you have a pull on different terrain such as flat / hill?

 

Hey thanks, Shutter. I was thinking the same thing but have no real experience with this stuff, just internet research.

All of my pulls are flat freeway on ramps. I will try to get a long hill pull this weekend and see if the results vary at all.

John Hancock

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IME I usually see FLKC when a knock event occurs and engine load is not changing rapidly, but in any case, from the 2 logs you posted it looks like there might be a bit too much timing (or a not enough fuel - but probably not since I believe the stock tune runs pretty rich) in the 4000-5000 rpm range.

 

As shutterbc mentioned, keep an eye on it. If you continue to see FBKC in that rpm range, you might want to consider getting that looked into. If your car tends to register knock events at those load/rpm regions and the correction mode is always feedback as opposed to fine learning, the car will actually knock each time. If the correction mode was Fine knock learning, after the initial knock event, the ECU would proactively pull back timing in an attempt to avoid additional actual knock when the engine is subsequently run through the learned load/rpm region.

 

 

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To add to my response above...

 

I took a look at the stock 2005 LGT/OBXT (my car) and 2006 LGT tunes, and it looks like Fine Knock Learning is disabled when engine load exceeds 2.20 g/rev and is re-enabled when engine load drops below 2.10 g/rev.

 

One of your logs shows the knock event occurred at 2.16 g/rev, while the other log shows the knock event occurred at 2.31 g/rev. In the log that showed the 2.16 g/rev knock event, engine load was actually > 2.20 g/rev a short time before, and so I think fine learning mode was disabled when the knock event occurred, and probably explains why a FBKC was applied. In the log that showed the 2.31 g/rev knock event, since engine load was > 2.20 g/rev, fine learning mode was disabled and that too would probably explain why FBKC was applied.

 

So... if your car tends to see engine loads > 2.20 g/rev, if the car registers a knock event, the ECU won't ever learn a correction there, it'll just let it knock (actual knock) and then reactively pull timing via FBKC (feedback knock correction), as opposed to learning a correction there and proactively pulling timing to avoid an actual knock event.

 

If you continue to see FBKC being when engine loads are greater than 2.10-2.20 g/rev, I would recommend either getting a tune to fix this (but maybe do some upgrades to make it more worth it :) or finding someone who can make this particular change for you (I or anyone else w/ the requisite familiarity and software can do this). It's a simple change to make, alter one or 2 table/cell values in the knock control section, save the map, flash it to the ECU. This was one of numerous changes I made to the original protune that was done on my car 3.5 yrs ago. If you can get the required open source hardware/software, it'll cost less than going the AccessPort route.

Edited by serx7
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Right. In my experience, I don't really pay attention to FLKC events on WOT pulls. It's feedback correction in response to knock, and that's what I look for on anything at high load.

 

Looking at the two logs, you have one event at ~5200 RPM and another at ~4200 RPM which makes me think it's not something harmonic (like a heat shield) and more likely real knock.

 

If it were my tune, I'd be inclined to pull timing to correct for this. Also if you haven't had your injectors cleaned, that could help too.

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I would pay attention to any knock that appears in a datalog, esp at WOT. FLKC indicates that at some point, actual knock did occur and the ECU decided to make a learned/stored/proactive correction for it. If the car is repeatedly run through the affected load/rpm and no additional noise is detected, it will in time start experimenting with adding some of the timing back. If the setup/tune is prone to actual knock in that load/rpm range, it will eventually knock again there and pull timing again in response.

 

You can tell if a given instance of FLKC in a datalog is from a previously learned correction or in response to an actual knock event that occurred, by logging the Knock Sum parameter. If Knock Sum does not change when FLKC appears in the log, it's a learned/stored correction from a prior actual knock event. If Knock Sum increments at the same time FLKC appears in the log, an actual knock event has most likely just been observed.

 

Agree on the suggestion to adjust the tune if the FBKC in OP's logs continues to appear in that same load and RPM range. Since it looks like it's occuring above the threshold at which FLKC is enabled, the ECU won't learn/store a timing correction there via FLKC and will therefore allow for actual knock to occur and then reactively apply a timing adjustment (FBKC). It would be a fair bit safer for FLKC to be applied there (and safer yet to pull down timing a little in the tune instead).

 

 

Right. In my experience, I don't really pay attention to FLKC events on WOT pulls. It's feedback correction in response to knock, and that's what I look for on anything at high load.

 

Looking at the two logs, you have one event at ~5200 RPM and another at ~4200 RPM which makes me think it's not something harmonic (like a heat shield) and more likely real knock.

 

If it were my tune, I'd be inclined to pull timing to correct for this. Also if you haven't had your injectors cleaned, that could help too.

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Thanks for preventing people from ignoring knock because I couldn't quite elaborate properly. :)

 

What I meant to say is I generally start with the flkc table instead of logs to plan adjustments for learned correction, and then check it against logs to determine if anything remaining is transient or happens consistently.

 

I probably wasted a lot of time doing it that way but I really learned how the ECU is designed by going through that exercise a few times.

 

Sent from my SM-G935T using Tapatalk

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  • 5 months later...

3rd post on this please help..I hope im in the right place now to post this...I am having some crazy numbers pop up on my AP...My Fine Knock Learn is all over the place and my DAM has went as low as .650...i am driving a 06 LGT sedan with cat back and running 91 ots AP tune....always put 93 in the tank...this has just started and has me very concerned...i attempted to log 2 3rd gear pulls...i hope i did this correctly! PLEASE PLEASE any input will be appreciated

 

2 data logs added...i hope they are done right:mad:

datalog1.csv

datalog2.csv

Edited by robburns201
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  • 5 months later...

...and I don't know why. I see its pretty lean and over-boosting when it started. Is that enough to cause it. It's extremely consistent and easily repeatable at will. Accelerating from cruise. My tuner isn't available until Monday.

 

2005 OBXT

catless UP

catted DP

Mishimoto TMIC

Cobb EBCS

Dyno-tuned

 

I feel like the car may have had boost leak when tuned, and now it's cleared up. I never found it, but my fuel learn changed when I realigned my TMIC. Here is a third gear pull. Any thoughts?

 

Stephen

BtSsm_20180126_155734_knock.csv

Edited by Spaceman Spiff
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If your AFR reading is coming from the stock O2, keep in mind that that reading bottoms out around 11.1. My stock O2 reading bottomed out at 11.13 while my AEM WBO2 would continue to read into the mid-10's. So, you might be running less lean than you think, or you might not. Your overboost is pretty minor, I wouldn't consider that the primary cause of your issue.

 

The -2.11 deg FKC at 3500 rpm is the one I'd be most concerned about b/c 1) it's occuring at/near peak engine load, 2) it's Feedback knock meaning the timing correction is in response to an actual detected knock event and 3) that FKC increases from -2.11 deg to -3.87 deg which implies to me that additional knock was detected even after 2.11 deg had been pulled out in response to the previous knock event. I would recommend you avoid WOT, esp in that RPM range until you get the cause sorted out.

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If your AFR reading is coming from the stock O2, keep in mind that that reading bottoms out around 11.1. My stock O2 reading bottomed out at 11.13 while my AEM WBO2 would continue to read into the mid-10's. So, you might be running less lean than you think, or you might not. Your overboost is pretty minor, I wouldn't consider that the primary cause of your issue.

 

The -2.11 deg FKC at 3500 rpm is the one I'd be most concerned about b/c 1) it's occuring at/near peak engine load, 2) it's Feedback knock meaning the timing correction is in response to an actual detected knock event and 3) that FKC increases from -2.11 deg to -3.87 deg which implies to me that additional knock was detected even after 2.11 deg had been pulled out in response to the previous knock event. I would recommend you avoid WOT, esp in that RPM range until you get the cause sorted out.

 

Thank you.

 

I need to get this back to my tuner. Last night I saw boost as high as 18.9, with a target of 16.9. Not good, especially on a vf40:eek:

 

I've seen target boost as high as 17.9, which is not supposed to be over 17.

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I stuffed my head under the hood while my son was tapping the gas off idle and I could hear a pfft pfft pfft, each time he hit it. I found the TMIC to TB hose was a little loose at the TB end. That must be what the knock sensor is hearing. Each time throttle is added, a little boost leak. I didn't leak test with enough pressure to find it. I tightened it up as best I could and I got rid of 80-90% of the knock. I think it's a little crooked so I can't get it all the way on. So I'll have to pull it off and clock it, but it's definitely much better. And I haven't seen an over boost either since I tightened it either. Seems weird that boost leak could cause over boost. If it could.
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  • 1 year later...

Thread bump!

 

 

Can anyone assist me interpreting this?

 

I'm getting FKC counts in low load cruising situations, anywhere from a typical -2.11 up to -7 or -9 counts.. I rarely ever really see FLKC and IAM has never dropped. This is in 4th-6th gear at a steady cruise, especially going on an uphill road.

 

I'm going to go over all the hoses and connections to make sure everything is tight, but this kind of came out of nowhere too.

Screenshot_20190507-210642.thumb.png.c9c47e58bc740e77acd98f44623118e9.png

Screenshot_20190508-103213.thumb.png.f2a05dc244eb145d3adbea690d31f1c6.png

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I get stray FKC spikes just hwy driving. No explanation.

Low load events, more often if Btssm is in the background.

Do you have a stock intake, I don’t see all positive values like that for fuel learn.

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No intake, but I took the TMIC off last night and tightened everything up. One of the intake lines was kinked a little, the BPV hose was jammed up at the clamp, the TMIC wasn't secured to the bracket so it was able to move around a bit, and I added a paper gasket on the BPV. That cleaned up the fuel trims, except in the second range, which is still a bit high. Fourth range immediately looked better.

 

I was running discounted 93oct gas this last tank, but I think btw a fill up today at Sunoco and getting everything tight it'll improve the tables and may help with some of the FKC.

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  • 2 years later...
  • 2 months later...
Why would I get knock events when I am at 1/4 tank or less? Bad fuel pump/pressure?

 

 

Could be fuel pressure related. Much more info/data would be needed to diagnose.

 

 

Way to revive an old thread by the way. Lol.

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Could be fuel pressure related. Much more info/data would be needed to diagnose.

 

 

Way to revive an old thread by the way. Lol.

 

Lol. Well I don't get more than -1.4 FKLC until 1/4 or less. then as much as -11.0 sometimes more Light to medium load and 2500-3000 rpm then as boost builds the knock drops to zero. Freakin Me out Man. Go fill-up and it goes away in 3-4 acceleration events until I'm back to 1/4 tank.

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Light to medium load and 2500-3000 rpm then as boost builds the knock drops to zero.

 

 

This sounds like the beginnings of rod knock. But, if the event is fuel level related it is most likely not. Probably time to check the fuel pressure and then the basket filter, pump, wiring and regulator if neccessary. Restrictions could cause low fuel pressure. A failing regulator could cause low fuel pressure. A failing pump could cause low fuel pressure. Poor wiring could cause a low voltage event at the fuel pump which results in low fuel pressure. Etc.

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This sounds like the beginnings of rod knock. But, if the event is fuel level related it is most likely not. Probably time to check the fuel pressure and then the basket filter, pump, wiring and regulator if neccessary. Restrictions could cause low fuel pressure. A failing regulator could cause low fuel pressure. A failing pump could cause low fuel pressure. Poor wiring could cause a low voltage event at the fuel pump which results in low fuel pressure. Etc.

 

I guess rod knock is a possibility but I would have thought the would be present as long as the oil is up to temp all the time. This literally only happens during low fuel. I will check fuel pressure , not sure I have a tool for that but I'll figure something out.

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