High knock sensor reading 18+

xunantunich

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I put this in the svt section.. i think i should have posted it here.. sorry . Basically im trying to figure out if these readings are false knock or tuner running to much timing..

This is the kind of random crap im seeing.. everything seems fine then BAM , 18 reading on the KS . To me at 70 Throttle angle , i should not see 29 spark advance .. i think its too much timing. Measured afr is .99 and 1.00 im assuming that is fine?? Im not WOT but 70 is pretty open.. help... :(.

Last instruction from tuner was for me to fix the false knock.. not so sure its false.. i tool logs over the weekend but have to wait till tmrw to hear from tuner..

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MastaAce03

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Check your plugs and see if there's any signs of detonation. Your fuel trims are perfect.

What's your timing at @WOT?

Put some race fuel or octane booster like VP Octanium in the tank and re log. If you're still seeing crazy knock after that, it's false. The octane booster could foul your sensors if you're still running cats, not sure if you are.




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xunantunich

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Thank you so much for reply , i actually had 2 plugs out today 1 and 8 and they looked really good .. im running 1 bottle of octane booster from royal purple and i filled up with 91 octane (no 93 here) only mods are the cj manifold , FR CAI and 47 # injectors.. we are doing logging to switch to E85 . .. but having this knock issue.. i spend hours under the car today checking exhaust..nothing..

i have a wot run in second that had very little knock but at the highest the timing was 29 deg while at WOT... i sent that log to my tuner.. also

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xunantunich

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At the highest RPM on this run the timing was 23 .. so i guess that makes sense as the rpm climbs the timing backs off.. im dealing with a big name tuner... i dont want to second guess them so as to maintain a good relationship.. so im kinda seeking a second opinion here :) .. i will get the booster you suggested from autozone this week and try it..

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MastaAce03

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Thank you so much for reply , i actually had 2 plugs out today 1 and 8 and they looked really good .. im running 1 bottle of octane booster from royal purple and i filled up with 91 octane (no 93 here) only mods are the cj manifold , FR CAI and 47 # injectors.. we are doing logging to switch to E85 . .. but having this knock issue.. i spend hours under the car today checking exhaust..nothing..

i have a wot run in second that had very little knock but at the highest the timing was 29 deg while at WOT... i sent that log to my tuner.. also

View attachment 1409540View attachment 1409540

Looking at the log you just showed, you're @29 degrees @WOT. Knock sensors shows -5.5 degrees which means your car is actually adding 5 degrees of timing. Which is a good thing, not bad. So if your car is @29 degrees timing with -5.5 degrees knock, your tune is commanding around 24 degrees timing and your car is adding timing to that to get to 29 degrees.

If your car was detonating enough to pull 18 degrees of timing, you would most definitely see it on your plugs and would have most likely blown your motor. What's your fuel pump duty cycle and injector duty cycle @WOT?


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xunantunich

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Thanks again.. ok so my tuner is commanding around 24 which sounds pretty safe.. and the car is pulling the extra timing on its own because it wants too.. then i get these random large knock numbers .. i guess i need to keep searching for false knock.. it kinda sounds that is most likely.. i will try the octane booster you mentioned on the next fill and go from there...

FP duty cycle and Injector duty cycle aren't getting recorded on the logs.. i guess i can add them ,so if 18+ knock would most likely cause plug or engine damage.. and i dont have any of that .. i guess i need to try figure out WTH is causing the false knock..

thanks again.
 
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j-wag

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I had a similar issue when getting my tune. I was getting all kinds of false knock. I checked my exhaust initially as it is one of the most common sources of false knock. Just like you I didn't find anything obvious. No signs of any exhaust components contacting the chassis and everything looked to have plenty of clearance.

But after a few frustrating weeks of trying a bunch of other things to cure the issue, i decided to take another look at the exhaust before throwing in the towel.

While under the car I used a rubber mallet and hit the exhaust in several spots and noticed a very very faint buzzing sound coming from the passenger side. Spend close to an hour trying to figure out where the buzzing noise was originating from, I was never able to pinpoint it.

I ended up loosing all of the exhaust bolts from the cats back and adjusted/realigned everything while trying to allowing the exhaust to sit where it wanted to naturally. Torqued the bolts to ford's spec and proceeded to tap on the exhaust again and I was not able to reproduce the buzzing noise.

I immediately went out to data log and all false knock was gone.

If nothing else cures your issue it might be worth looking at the exhaust again, as with my car there were no signs of the exhaust causing false knock and I looked it over meticulous the first time.




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xunantunich

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Thanks for that .. while under there banging on the exhaust over the week end , I did find that my stock H pipe , "buzzes" when you bang on it.. the actuall ribs of the h pipe seem to vibrate.. I verified by putting my hand on the h pipe and banging.. then the buzz goes away.. ill try wrapping the actuall H section with something to kill vibration and go from there..
 

Kman11

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Ughh false knock is beyond annoying. I'm fighting the fight myself.

Are you getting an knock at idle when revving?
 

5lho

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It has to be false. The ecm can't pull that much timing and you'd sure as shit know if it did.
 

xunantunich

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Im pretty sure my tuner is trying to kill me .. btw this was done on a closed race circuit.. ;)
he sent me a new tune and asked for wot in 3rd up to 7850 o_O... runs like a bat out of hell false knock or not.. anyhow , i lost nerve at 7200 rpm and let off.. im done data logging untill i can figure this knock thing out.. the log is attached in the zip if anyone finds logs amusing...
 

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WIST2013GT

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I assume this is what you are talking about in the log? Looks like false knock to me.
 

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Shaun@AED

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Looks like a Live Link 'glitch' to me, I'm surprised your tuner did not point it out to be so. I see glitches in data logs regularly and it's why I disregard the 'Min/Max' values in the data logs.

1. It would not make sense to allow the knock sensors to pull 20+ degrees timing.
2. Spark advance does not reflect the knock values (spark does not drop 20+ degrees)
3. There are rates of retard/advance in seconds per degree and it is not possible to go from adding 3.5 degrees timing to removing 21 degrees then back to adding 4 degrees within .05 seconds.
 

xunantunich

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Actually , I was looking at the time frame
Looks like a Live Link 'glitch' to me, I'm surprised your tuner did not point it out to be so. I see glitches in data logs regularly and it's why I disregard the 'Min/Max' values in the data logs.

1. It would not make sense to allow the knock sensors to pull 20+ degrees timing.
2. Spark advance does not reflect the knock values (spark does not drop 20+ degrees)
3. There are rates of retard/advance in seconds per degree and it is not possible to go from adding 3.5 degrees timing to removing 21 degrees then back to adding 4 degrees within .05 seconds.

I will mention this to the tuner. I was thinking the same that the changes were huge and almost instant..
 

xunantunich

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Shaun,
Thank you for taking the time to contribute on this thread . The tuner has verified it is a glitch and not knock.. I think we have been dealing with this issue from the start. Im waiting for further instruction from him. Thinking about it .. I grabbed an old crappy laptop running windows 7 and have been using that to log.. maybe the laptop also has something to do with these glitches.. hopefully Ill be burning E85 soon and then ill get rid of the cats next. :)
 
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