Need some help with burst knock
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From: Armpit of East TX
Need some help with burst knock Here is a snippet from a log file which I think is burst knock. If there is something you want to see with this, let me know, I prolly have it logged too, I just cutit out for the sake of keeping it simple.
Notice the massive drop in timing on the 5th row and how it tries to resume timing. The HO spark tables say it should maintain 17 degrees. This makes it feel like the truck really falls flat on it's face.
What would cause burst knock like this? Is there a PID in EFI that will show burst knock?
I did some searching on Burst knock, but came up with next to nothing ... The onlyh thing I got from searching is that it is anticipated knock which may or may not be true.
Code:
TP % RPM lb/min MAF Hz ADV KR IAT °C ECT °C CYLAIR g/cyl 47.8 2950 20.55 8512 17 0 34 81 0.79 47.8 2945 20.55 8502 17 0 34 81 0.79 47.8 2962 21.03 8543 17 0 34 81 0.81 51.4 2953 23.73 8807 13 0 35 81 0.91 57.6 2782 23.08 8841 2 0 35 81 0.94 57.3 2893 23.36 8892 6.5 1.3 35 81 0.92 57.3 2966 24.43 8979 7 1.2 35 81 0.93 57.3 2923 23.57 8974 5.5 1.1 35 81 0.91 57.3 2918 23.78 8911 6 1.1 35 81 0.92 57.3 2952 24.43 8958 8 1.1 35 81 0.94
What would cause burst knock like this? Is there a PID in EFI that will show burst knock?
I did some searching on Burst knock, but came up with next to nothing ... The onlyh thing I got from searching is that it is anticipated knock which may or may not be true.
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did you feel a shudder when the car lost 200rpm? or anything clanking? i know when my pace-suckers hit the kmember the ecu saw it as knock in a big time way. what about misfire counts at the point? i dont see a cam on you, but a bad TQC could induce misfires.
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No misfires that I know of ... that's one thing I didn't have logged. There is a cam in there, 216/220 low lift 114+2.
No clanking .. no KR to speak of in that snippet. The only place I see that timing could be pulled in my program is Burst Knock and it's roughly 14 degrees max, which is about what I saw. The converter is relatively new, only about 3-4000 miles on it. FWIW ... there's only about 12 on the truck all together.
No clanking .. no KR to speak of in that snippet. The only place I see that timing could be pulled in my program is Burst Knock and it's roughly 14 degrees max, which is about what I saw. The converter is relatively new, only about 3-4000 miles on it. FWIW ... there's only about 12 on the truck all together.
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you got efilive? If so log all 8 cylinders misfire count and go do it again. My cam was throwing misfires all over the place. idling, i could count them 1 2 3 4 5 6 7 as the seconds went up. the tuner desensitized something, oddly that was when the verter started locking up alot better. i need to go out and log it some more since the changes were made. Even stock cars with some miles on them will throw misfires but not so often. Anything unbalanced in the rotating assembly (verter,asp, etc) can easily cause misfires, specially a cam. I was quite horrified the first time i logged my misfires after the bolt-on/cam install... even though i got 0 KR i had like 20-30 misfire count just idling/cruising around almost always on all 8 cylinders. I was told cam's do this. damn sensitive computer is all i can say.
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From: Armpit of East TX
OK ... It will be later tonigh before I can do that though. I don't think it's a misfire thing. I didn't think that misfires would cause timing to be pulled would it?
Just so we're on the same page ... I changed my sig some, I think you were reading the mods on my old truck. Just in case your not up with the truck parts the RADIX is a MagnaCharger blower.
Just so we're on the same page ... I changed my sig some, I think you were reading the mods on my old truck. Just in case your not up with the truck parts the RADIX is a MagnaCharger blower.
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One way to figure out if it is burst knock would be to change the value in the Edit table. Its set at 14 now, so lower it down to 9 or some other number that is not the same as any of the other KR tables. Then if you get 9* KR next time, you can be pretty sure it came from the burst KR table.
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From: Armpit of East TX
deezel .. I will try that. I am not seeing any KR on the logs, check it above. I did some reading last night and found that it's believed that burst knock isn't shown on a scan tool as KR because it isn't actually KR, it's the PCM thinking that there is fixing to be a decent amount of knock.
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Oops.. I didn't look closely enough at your data. 
I see the timing drops but no KR for a few frames and only ~1*KR at that point...
Yes, I think I saw somewhere that maybe burst KR does not show up on KR logs. Another way to test if its burst KR would be to drastically increase the values in the Airflow to Enable Burst KR table. Maybe 300% or more... with a SC you're getting a lot more air than the stock tune was set up for. Good luck with the tuning...
I see the timing drops but no KR for a few frames and only ~1*KR at that point... Yes, I think I saw somewhere that maybe burst KR does not show up on KR logs. Another way to test if its burst KR would be to drastically increase the values in the Airflow to Enable Burst KR table. Maybe 300% or more... with a SC you're getting a lot more air than the stock tune was set up for. Good luck with the tuning...
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I thought I got rid of any burst knock retard that would have come into play at my operating temp, but it is still happening. I am going to try 0'ing out all the tables and see if that rids the problem before I rule it out though. The EDIT manual is pretty vague about the burst knock tables and I'm not sure I understand what all of that is.
I did get some logs with misfire data in there, but it's on my laptop and I'm gonna let it charge up some before I get back on it. I will get those up later on.
I did get some logs with misfire data in there, but it's on my laptop and I'm gonna let it charge up some before I get back on it. I will get those up later on.
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OK ... I looked over the new logs. I know it was going on, but the added 8 PIDS from the misfire counts was to much to get an accurate reading on the timing pulls.
I did get enough info from it to tell the only time I'm getting any considerable misfire counts is at idle, more in Park.
I did get enough info from it to tell the only time I'm getting any considerable misfire counts is at idle, more in Park.
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From: Armpit of East TX
Burst knock is ruled out ... all but removed it in all tables I could find that was anything related to burst knock.
Something I did notice that was a little strange is that in one of these instances, the o2's are reading .3xx and the injector duty cycle goes from 55+ down to 30'ish. Keep in mind this is at 65% throttle with PE coming in at 40.
Something tells me I have more problems than what I'm hoping it is. The o2 dropping down so low and timing running where it should be while it's that low is kind of worrysome. Would anyone like to volunteer to check out my EFI log? I can get you the EFI or a CSV log.
Something I did notice that was a little strange is that in one of these instances, the o2's are reading .3xx and the injector duty cycle goes from 55+ down to 30'ish. Keep in mind this is at 65% throttle with PE coming in at 40.
Something tells me I have more problems than what I'm hoping it is. The o2 dropping down so low and timing running where it should be while it's that low is kind of worrysome. Would anyone like to volunteer to check out my EFI log? I can get you the EFI or a CSV log.
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PE at 40% should be ok. Have you done anything to the PE curve? I have noticed that the stock PE curve comes on a little late... you might consider making the PE curve flat - using the highest value (from ~4800rpm) all the way down to your lowest possible rpms for PE mode.
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From: Armpit of East TX
The tune that the RADIX kit comes with does make some changes. I'm not to sure what and how it changes it though. I did start off with the tune copied from another RADIX install, but I made sure all the tables and stuff matched up before I started copying and pasting. I have not made changes to that table besides what the RADIX tune changed.
I will email you once I get back on my laptop.
I will email you once I get back on my laptop.
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From: Central, MA
Flyer, I'm just looking into some burst knock stuff, and ran into your thread. Did you get this worked out?
You're not hitting COT (Cat Over Temp), are you??
I don't think my truck is set up to pull timing when that kicks in, but I hear that it will throw the O2's and injector readings off.
You're not hitting COT (Cat Over Temp), are you??
I don't think my truck is set up to pull timing when that kicks in, but I hear that it will throw the O2's and injector readings off.
PCM pulls timing for burst knock on a delta-CylAir
threshold and it also changes timing based on where
you move, on the CylAir-based timing map. I would
add the Dynamic Cylinder Air PID to your logging
and then look at your spark table step by step,
if you see you are on the spark value the table
says then that's that; if you are retarded to some
degree then look at the delta CylAir (make a
column with stepwise difference) and see if this
looks like a burst knock event trigger. I haven't
yet gotten the definition of what the HPTuners
burst knock delta threshold has as its timebase
but you should be able to pick out any big jump
anyhow.
To me it looks like you did get a burst knock
pullback applied, it was a bit over-the-top,
but once it started to release it exposed a
pin condition (which was its purpose for
coming on, to cover that up).
MAP transients expose the quality of your
speed-density tune, the MAF is too slow to
give accurate dynamic readings and you
probably want to see MAP, and work on VE
table at the MAP & RPM to get a little more
dynamic enrichment (effectively) by making
sure your SD tune is fat enough to party.
That's my guess.
threshold and it also changes timing based on where
you move, on the CylAir-based timing map. I would
add the Dynamic Cylinder Air PID to your logging
and then look at your spark table step by step,
if you see you are on the spark value the table
says then that's that; if you are retarded to some
degree then look at the delta CylAir (make a
column with stepwise difference) and see if this
looks like a burst knock event trigger. I haven't
yet gotten the definition of what the HPTuners
burst knock delta threshold has as its timebase
but you should be able to pick out any big jump
anyhow.
To me it looks like you did get a burst knock
pullback applied, it was a bit over-the-top,
but once it started to release it exposed a
pin condition (which was its purpose for
coming on, to cover that up).
MAP transients expose the quality of your
speed-density tune, the MAF is too slow to
give accurate dynamic readings and you
probably want to see MAP, and work on VE
table at the MAP & RPM to get a little more
dynamic enrichment (effectively) by making
sure your SD tune is fat enough to party.
That's my guess.
