detecting false knock
03-31-2012, 07:23 PM
#1
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detecting false knock Is there any way to detect wether or not knock readings are false or not? Im getting readings under 1 while accelerating in od and when I hit wot I get readings anywhere from 4-10. Just trying to figure out if it's true knock or just my headers/exhaust. The engine isn't making any strange noises. I'm using EFILive to datalog. Also wondering, if it is in fact false knock is there a way to either tune the knock out by making it less sensitive, or completely eliminate the knock sensor from the tune (if that's even a good idea at all).
Last edited by puddingmmmmmmmm; 04-02-2012 at 06:20 PM.
04-02-2012, 09:20 PM
#3
What octane gas are you running? Seems like it is hitting max retard while in PE mode. Could be false knock from Burst Knock also. You can try to zero those tables and see if it goes down or soften them up.
The other ways are to run alot higher octane mix with some torco additive or race fuel, or you can subtract the amount that it is knocking in those cells and see if it goes down. You should not have to take out a whole lot to see at least a decrease though.
Remember, knock can be cause from an overly lean condition OR an overly rich condition.
The other ways are to run alot higher octane mix with some torco additive or race fuel, or you can subtract the amount that it is knocking in those cells and see if it goes down. You should not have to take out a whole lot to see at least a decrease though.
Remember, knock can be cause from an overly lean condition OR an overly rich condition.
04-02-2012, 09:26 PM
#4
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I too have struggled with false knock before. My advice would be to start by replacing the knock sensors, and harness, if you have any doubt about them. I believe that is commonly a source of false knock.
You can take the knock sensors out of the tune, however you have lost some of the advantage of a modern engine like this. You would basically be tuning your timing like an old school engine without knock detection capability. This has been done for about 100 years before the invention of knock sensors, so it can be done, but I wouldn't want to give up the ability to detect knock before I can hear it.
If changing the sensors doesn't help, the next 2 places to look are the balancer, and then checking out the converter as potential sources of false knock. It can be difficult to hunt down.
You can take the knock sensors out of the tune, however you have lost some of the advantage of a modern engine like this. You would basically be tuning your timing like an old school engine without knock detection capability. This has been done for about 100 years before the invention of knock sensors, so it can be done, but I wouldn't want to give up the ability to detect knock before I can hear it.
If changing the sensors doesn't help, the next 2 places to look are the balancer, and then checking out the converter as potential sources of false knock. It can be difficult to hunt down.
04-03-2012, 07:22 PM
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gectek; I only ever run 93 octane in my car. What exactly is burst knock?
scottybg; I really don't think the knock sensor is faulty but I guess there's no way to actually tell besides replacing. Don't really have the money right now to just throw parts at it though and it not be the problem.
joecar; files posted, thanks
scottybg; I really don't think the knock sensor is faulty but I guess there's no way to actually tell besides replacing. Don't really have the money right now to just throw parts at it though and it not be the problem.
joecar; files posted, thanks
04-04-2012, 07:12 PM
#7
You can look at the sensor and usually tell. If there is rust on it, then honestly it should be replaced and the grommets that go over it sealed VERY well to keep it from happening again.
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04-04-2012, 07:55 PM
#8
Burst knock is knock induced by the computer for large changed in the cyl air dynamic. It is in anticipation of knock, but is also there to help soften the transition up. Find that cell and disable it and run it again and see if you have that problem.
I am not sure where it is on EFI Live as I only stick to HPT most of the time. Should be in your spark tab. Called Burst Knock.
I am not sure where it is on EFI Live as I only stick to HPT most of the time. Should be in your spark tab. Called Burst Knock.
04-04-2012, 08:03 PM
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I use tunercat to tune, efilive to data log, i'll try disabling it and see what it does when i have a chance. Is this going to hurt anything if it's actually knocking?
04-04-2012, 08:51 PM
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Here's a picture of what I have. Am I just editing Burst Knock Enable%Diff Air flow thresh to 0% and Burst knock enable coolant temp thresh to somewhere out of it's range?
04-04-2012, 09:35 PM
#14
Hmm ok. Intersting. I would still run it with the Burst knock turned off and see what happens.
Otherwise you will have to go through and check the knock sensors first then either try subtracting the amount of knock or use an additive that will give a higher octane. Otherwise, it could just be noise picked up by your knock sensors. From exhaust, trans, etc.
Otherwise you will have to go through and check the knock sensors first then either try subtracting the amount of knock or use an additive that will give a higher octane. Otherwise, it could just be noise picked up by your knock sensors. From exhaust, trans, etc.
04-06-2012, 05:41 PM
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Alright, got a chance to take it out today after turning off burst knock. Seems like the knock retard is not as bad as it was before, but it's definitely still there. It doesn't go as high as 10, but it does get anywhere between 2-6 through WOT. It's only taking about 5-8 degrees of timing instead of 12-14 like it was before. So, what would you recommend, if it could be my exhaust,trans, headers, making to much noise, should I pick up an lt4 knock module? If it is one of the above, wouldn't taking the timing out until the knock goes away only be hurting me and would that even work since it would still be picking up false knock from the headers and etc.
04-06-2012, 06:08 PM
#17
TECH Resident
When I had a LS6 with 11.8 compression, it knocked until I lowered the timing to 26 across the chart.
100 octane race fuel stopped the knock also. If you lower the timing and it stops knocking, you will prove that there is nothing false about it. If you lower down to 24 total, and it still knocks, you may have faulty sensors, or other bad inputs. I suspect you may have some low octane fuel in the tank right now. Keep scanning, and trying all of the other good ideas above.
100 octane race fuel stopped the knock also. If you lower the timing and it stops knocking, you will prove that there is nothing false about it. If you lower down to 24 total, and it still knocks, you may have faulty sensors, or other bad inputs. I suspect you may have some low octane fuel in the tank right now. Keep scanning, and trying all of the other good ideas above.
04-06-2012, 06:19 PM
#18
I would pick up an LT4 knock module yes if you can. I think WS6 store carries them. Otherwise I think you can desensitize them in the tune, but I would try the higher octane additive first to make sure.
04-06-2012, 06:22 PM
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I only use 93. Unless something has been wrong with the gas I've been buying for months now, then I highly doubt it's octane related. I'm kind of confused on how to change timing w/ tunercats. If anyone could help me out with it that would be great.