Advanced Knock Sensor Tuning

[CCS86]

Hey guys,

Any insight on these settings, beyond the brief description in editor?

Knock sensor settings.jpg


Are the values under the "Knock Threshold" tables, the "noise floor" referred to in their description?

How do the other settings affect knock timing response?

[Auto-Hentzschel]

if you adjust these tables, you should use a knock monitor. As higher the values as lower the knock sensibility.
Pley Knock Test3.jpgPley Knock Test2.jpg

[veeefour]

Hey guys,

Any insight on these settings, beyond the brief description in editor?

Knock sensor settings.jpg


Are the values under the "Knock Threshold" tables, the "noise floor" referred to in their description?

How do the other settings affect knock timing response?

Those are S197 specific values. Raising threshold will desensitize the sensors. How much? It's kinda shooting in the dark without external knock sensors as Henry mentioned.

PLEX is a way to go, I'm using one myself. If you do not want to spend that much just get yourself a 10USD stethoscope - just make sure you know how the knock sounds.

[CCS86]

if you adjust these tables, you should use a knock monitor. As higher the values as lower the knock sensibility.
Pley Knock Test3.jpgPley Knock Test2.jpg

Oooh, that PLEX is pretty sweet!

Slick to use cyl #1 spark trigger and a high accuracy clock counter to establish per-cylinder knock. I hadn't thought of that approach.

My strategy has a switch for [global / per-cyl] knock detection. Have you guys tried that mode? I wonder if the PCM sully supports this, and if so, why it isn't used by default.



I definitely didn't plan to start turning dials on these detection filter settings, especially on my boosted application. I have already allowed the knock system more latitude for advance/retard and faster rates. Obviously, accurate detection is foundational to the whole system, and adding a PD blower right over the knock sensors can skew the factory sensor tuning. My manifold does have a composite heat barrier in contact with the heads, which may help damp some of that noise.

I wish we had live tuning to allow holding a steady rpm and increasing spark from a very safe value, to the onset of knock to help tune these settings. Doing a reflash for everything really jams up that process.

Have you guys used the PLEX device to tune these "frequency filter" settings? Do you understand the function of each?

My best guesses:

Knock Threshold: Per cylinder tables that set the magnitude of sensor activation to define "noise" vs "knock"
Window Length: Time period to count individual knock events
Window Offset: A time shift of the window, from the rising edge of sensor activation
Up/Down Avg Constant: ??? Some time constant to control how long an individual knock event is considered in an average?
Fast Mode Events: ??? Number of knock events occuring in the time window, to determine fast/normal knock, and how aggressively to respond?