Well ?? it depends on what our definition of a"little knock" is. This is a good question and I've thought long about this. There are 2 different conventional wisdoms pertaining to knock retard. One is that NO KNOCK is tolerable and the second is that a little knock is tolerable.
The ECM's max KR attack rate is 29.9 degrees under PE mode and 15 degrees at other throttle positions.
So is 5% too much? that would be 1.4 degrees of retard or 10% 2.9 of KR. That addresses position #2.And the consencus is that 2 degrees is acceptable.
I feel that different engines,with different mods and different tunes can tolerate KR differently.
Because we drive F bodies I think our cars are prone to false knock more so than the GN's. That being said, I was convinced that last summer I was wrecking my headgaskets. I was getting knock numbers as high as 14.9 and as low as 1.2 during WOT blasts. I began hunting down false knock areas and cleaned up alot of my big KR numbers, but still had low KR numbers. So out came the engine and other than a wiped cam lobe my motor was normal. No bearing wear, no headgasket problems, nothing.
Fast forward, the engine's back in and with a new chip,trans and convertor and some other things I still have small KR numbers. Usually in the 1.2-.2 range. I'm convinced of one of two things here, one, it's false because with the PL I can see that my tune is conservative and I run 20-22PSI all day long and two, my engine tolerates small knock! Either way I drive right through them with no ill effects.
By no means am I done chasing these little numbers down, but I no longer lose sleep over it. And who knows? I may be changing headgaskets in my future. But I'm comfortable in the the way my tune and engine manages knock.
But for you Dave I would figure out how these numbers appear. Do they pop up big like 6.1 and then decay to 0.0 right away or do they start at 1.1 and climb to 6.1 and then decay. A sure sign of false knock is a sudden 14.9 KR then a decay.
You're at 15 psi and that's less than the factory max position.So you "should" be not seeing real knock. But the boost spikes will make that tune go lean and could be the knock culprit.
As an aside...the Caspers knock gauge is fine. The problem is you're using it improperly. It is reading directly off the knock sensor through the ESC module,which is a bandpass filter. It reads knock as it happens,real,false or whatever. The scanmaster on the other hand is reading KR as the ECM is reacting to knock. The ECM takes the signal from the ESC and starts to accumulate it and decides if and how much timing in degrees needs to be removed to make the knock go away.
So, the caspers gauge reads all knock that is "heard" and shows it in the display. The scanmaster shows how much retard is being applied to quell that knock. The Scanmaster is what you need to be watching. It's more important to address Knock that the ECM thinks is real. The Caspers gauge is the first warning that knock is being heard and you can use that to figure out when and where the knock occurs. Such as a shift point, a boost spike. But don't get too wrapped up in what the Caspers gauge is showing, but just use it to track down the problem and when it lights up look at the Scanmaster to see if the ECM thought it was real.
If you have the 5.6 TT chip I would start looking at the O2 numbers at the top end of a run and start tweaking fuel to get it around 800mv. I would also find out why that wastegate isn't controlling your boost. A fat tune at 15 psi will be a very lean tune at 20psi.
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