Knock Sensors not registering anything?

[MattKatz]

06 TBSS, LS2, stock harness, TVS 2300 Blown truck, MAF Tune.

I personally installed all motor and harness myself, over a year ago, an I'm 99.998% sure I missed nothing.
After trying to pulley down on my blower last weekend, and getting what we thought was audible knock, we noticed nothing showing from The sensors. We adjusted the sensitivity lower, still picking up nothing. Not sure where to start looking, but I can't say I've ever heard of two knock sensors going bad at once.

Open and looking for suggestions here.

[262]

How far from stock is the knock sensor settings?

[MattKatz]

We tried stock which is 400 I believe, now it all the way down to 275, and I think we even tried 200, and 100.

[planethax]

Can easily check the KS' by disconnecting both KS electrical connectors.
Connect one test lead from the DMM to the signal circuit terminal on the KS, and the other test lead form the DMM to the low reference circuit terminal on the KS.
Set the DMM to the 400 mV AC hertz scale, and wait for the DMM to stabilize at 0 Hz.
IMPORTANT: DO NOT tap on plastic engine components.
Tap on the engine block with a non-metallic object near the KS while observing the Hz signal indicated on the DMM display.
The DMM should display a fluctuating frequency while tapping on the engine block.
Repeat the above procedure for the KS on the opposite side of the engine block.

[IDRIVEAG8GT]

I'm not going to be much help here, I just came to say SIG WIN!

[MattKatz]

So youre saying basically both leads to the knock sensor itself....it's just a two wire iirc right? No harness on it?
Not sure if my meter does Hz though. But I'm sure I can get one.

[MattKatz]

I'll have to find another meter....mine does everything but Hz....and as a guy who uses a meter daily by trade, I can't say I remember a meter with a HZ scale at all in looking at them, but I'll have to ask some of my other service guys.

[planethax]

Yes to the sensors themselves.
Funny, both my Snapon and Fluke meters have HZ

[MattKatz]

Snap on I expect, I have a fluke and UEI, neither have it, but I never need it either so I didn't bother opting for one with it. I have a buddy who has one, I'm gonna borrow it and try youre method, I gues if they register nothing they are junk? I have a spare pair, can I check them off a motor?

[planethax]

I have never tried them off the car but in theory i guess you could but I dont know what hz reading to expect.

[MattKatz]

Well I tried this off the block with my extras, and putting them flat against my counter and tapping near them produced a change in HZ. Harder I tapped, the more change I got. Now I'm going to try to test the ones on my block, if nothing I'll put these two that appear to be working on and see what happens.

[MattKatz]

Well it looks like the sensors are fine, codes are enabled, nothing is showing up, so what's that leave me with. What else could cause these not to read? Do the just stay that quiet if there is no knock? Is there always some sort of knock going to show on almost any tune?
I'm slightly baffled as to what's causing this.

[10_SS]

I get occasional 0.25-0.5 degrees of knock, occasionally, light throttle, light accell... ~1500-2000rpm, 30-40 degrees of timing. 93 octane. Stock tune,

Turn all of your per cyl. knock Status bits on and see if they are detecting each cyl. knock as they should be. You should see random occasional knock triggers on random cyl.

Also try changing/adding all knock PID's to your log maybe one that you need is not there.

Attached are my "normal" knock amounts. Not sure if you'll see the same as what I see, but I have "Knock" and "Burst Knock" logged, along with per cyl knock status bits. Real knock is separate from burst knock.

[MattKatz]

I see burst knock...but nothing else. I'll have to look into what PIDs I'm trying to look at.