Knock Sensors

I know this has come up several times, but it seems there's some information out there now that I'm hoping someone can share. I know the Megasquirt is capable of using knock sensors, but the factory knock sensors on the gen 3 Hemis are a little weird by some standards. They're not the typical 1 wire style "microphones" that a lot of the GM ones are. However, I noticed that the EFI Source MS3 Gold kit comes with knock sensor inputs and someone mentioned on a recent thread about Drag Week that they had knock control on their setup. How is this system set up? Does it use the factory sensors or do you use a simpler 1 wire style? Is there extra circuitry built into the computer or is it handled entirely with code?

It would be awesome if EFI Source would divuldge some of the info on this setup if possible. I'd really like to utilize my sensors since I already have them, but I've been a little stumped at how to incorporate them into my system. I've looked at some external filtering circuitry and understand effectively what it's doing, but I can't figure out if my sensors are working to begin with.

Toyota uses a tuned knock sensor to filter out other engine noises. Im sure the MS uses/can use GM signaling. Its just a signal to retard timing.

RIght, most 1 wire setups are basically just a microphone that produces a voltage that varies with intensity of vibration. A knock event is seen as a large spike in that output. However, as you mentioned, some knock sensors are bandwidth specific and only respond to vibrations in a certain frequency (tuned for the engine they're being used on). I see the EFI Source Megasquirt Gold setup does have knock sensor control built in, and I know the Megasquirt can do it, but I'm curious how the EFI Source kit accomplishes that. Do they use the stock sensors or do you have to swap to a particular one to work with their system?

My harness plugs into the factory sensors so they must have them sorted.

Interesting, hopefully they'll chime in here and share some of their secrets. I'd mainly just like to know if there was additional circuitry they built into the system or if it's something that can be handled entirely with coding. Would love to have them in my system as a check if nothing else. My ignition is currently controlled by the MSD Hemi 6, but being able to log knock is better than nothing.

There is a special knock module board that must be installed in a megasquirt box. You can add one to your box.

Last I heard, the knock module was installed and wired in the efi source boxes, but tuning the sensor input hasn't been done yet.

http://www.msextra.com/doc/ms3/knock_module.html

http://www.msextra.com/doc/ms3/ignition-settings.html#knock

This is something I think would be nice for highway cruising and allow it advance under low rpm light conditions. Also good for crap gas we may encounter on the road.

Hmm, saw that knock module the other day. Unfortunately I have an MS2, so might be a little harder to work into my setup. Any idea how the sensors are wired in the harness? Would anyone mind checking pins for me to see where they go? Tried on my grandparents Ram a while back, but what I got didn't make a lot of sense and it was a stock computer setup. Since they're 2 wire I'm guessing it's either a dedicated ground for one wire and signal on the other or 1 wire is a bias voltage (say 5v) and the other is signal return. The reasoning behind this would be that the computer would always expect to see ~5v coming out of the sensor, so if it doesn't it knows the sensor is bad, so it's used as a check feature.