[Bones Malone]

Are knock sums for each cylinder supposed to be at zero?

Because I looked at the knock sums cyl 1 was 3 cyl 2 was 7? Aren't the values for knock always supposed to be zero? Sry if its a newb question. Any help is appreciated!

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[hutch959]

mine was at 32 today....stupid knock sensors.
they are not very accurate.
only pay attention to them under load.

ive witnesses them goinng up over bumps in the road.

 

[Socko]

the only real value to the knock sum values to identify what cylinders knock is being detected on by cross referancing what cylinder had knock sum increment when knock shows up in fkl or fbk tables. All other knock values are ignored by the ecu as there is extensive tuning of the knock sensor to limit false positives by subaru. I assume they don't want their motors blowing up so I assume its mostly right in areas where it could cause damage.

There are a number of threads that address the concern here and on cobbs forums, they all end with, dont monitor knock sum as it will drive you insane.

 

[Bones Malone]

mine was at 32 today....stupid knock sensors.
they are not very accurate.
only pay attention to them under load.

ive witnesses them goinng up over bumps in the road.

Lol wow ok, I thought it couldnt be that accurate. I was at idle and noticed a knock event lol.

the only real value to the knock sum values to identify what cylinders knock is being detected on by cross referancing what cylinder had knock sum increment when knock shows up in fkl or fbk tables. All other knock values are ignored by the ecu as there is extensive tuning of the knock sensor to limit false positives by subaru. I assume they don't want their motors blowing up so I assume its mostly right in areas where it could cause damage.

There are a number of threads that address the concern here and on cobbs forums, they all end with, dont monitor knock sum as it will drive you insane.

Ok thank you Socko! Makes me.feel alot better. The reason I ask is because when my 1st motor went, I was monitoring the knock sum in cyl 3 and it kept going up to the point of 100+ on my drive to my gf's. (I also knew I had a cracked ringland at the time from the way she would crank at start up). After seeing this I decided to get it over with, dropped it down a gear, did a nice pull and there you go, blown motor! So the knock sum must be SOMEWHAT accurate. I remember seeing it keep going up and up, was pretty crazy and I knew it was inevitable.


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[hutch959]

buttttt...... was the # 4 knock sum climb fast while you were under load.?
i would have expected, that with crack ringlands, it would count alot under load.
i find when my motor is under load, the knock sum counts (for the most part) stop.
its when im cruising or downshiftinng that they seem to add up quick.
and, its very bad when the car is cold. even if i let it worm up. Oil probably cold.

 

[Socko]

cause the knock sensor is on cylinder4. therefor noise in 4 is picked up more.

 

[bzbuzz]

I've seen many people having same issue. mine does as well. i see 100+ specially on cyl 4 since the sensor is close to that. my friend's 2011 sti has same issue. my car has no issue 30k miles protuned 320 whp.

 

[AgustinSTI]

if my knock is at 47 is that bad im sorry its a newb question but i just am reallt afraid about the ring land failure that the 11-14 have

 

[CR_STI]

if my knock is at 47 is that bad im sorry its a newb question but i just am reallt afraid about the ring land failure that the 11-14 have

Might be, but probably not. As is mentioned earlier in this thread, knock sums can increment at idle because the knock sensor can't tell the difference between normal combustion and knock at low loads.

Are you seeing FBK or FKL? Posting a log might be useful as well.

 

[TurboMoe]

Thread from the dead! j/k, at least you searched.

Saying "knock is at 47" is kind of vague, since the values will be different for each cylinder, #4 being the highest. Last time I did a long 20 minute log my sum for #4 was over 100.

The thing to look for is when the knock sum(s) increase. On my car the only time the knock sums increase is at lower rpm on deceleration, and even at idle, nothing I'm worried about. I would only worry about it if you saw something like the knock go from 40 to 47 during one full throttle pull, where the sum increased under high load at full boost. However, if that's the case, you'd see feedback knock and other indicators that something isn't right.

 

[Keananjuan]

I've seen many people having same issue. mine does as well. i see 100+ specially on cyl 4 since the sensor is close to that. my friend's 2011 sti has same issue. my car has no issue 30k miles protuned 320 whp.

so what was the problem the whole time? It was just a sensor?

 

[Bizzy1971]

All, Here is a link to the full AP monitor list from Cobb, explains it well:

Subaru Monitor List - Customer Support Center - Confluence

cobbtuning.atlassian.net

 

[WrxSubi13]

So call me a dumb ass but I found out why my Cobb AP was showing high numbers for cylinder 1-4. It was because I had no oil in it