Just curious how if the NON-SMART V3.2 clients are able to log knock.
Any information would be greatly appreciated.

 

I really think you need to knock buffer to do that.

 

What we've been calling knock is actually a buffered noise signal. So, as freedom said you need the hardware to read the signal.

d

 

I'm not so sure about that.......the factory ECU reads knock.....so we should be able to interpret that signal without the buffer. Hell the 92 DSM ecu could spit out degree's of knock so should the EVO ECU.

 

But how would you wire it up? As it stands, non-SMART xedes only know about knock attenuation state, not noise level.

d

 

Well internal to the ECU they are processing the knock micrphone's output. Thus if one has a software patch to the ECU such as exists for the DSM's, you could have the same capability.

That said the knock microphone needs amplification to permit the Xede to digitize the signal. Also the sample rate of the Xede might not be high enough to capture knock events (unless you are lucky). It appears that the knock buffer is more than an amplifier from the little I played with it.

 

Concur.

I think all that attenuation is just that. They load down the knock microphone's input to reduce the signal seen by the ECU. Thus this is an ouput from the Xede, not an input.

 

Old school tuners have been hooking tapping the knock sensor for years.....without a buffer.

If the sensor is hearing noise and the background noise increases roughly proportionally with rpm it should be easy to tap into the signal and read knock.

The EVO ECU dynamically adjusts its background noise threshold so it knows when an amplitude event (knock) is out of spec and then pulls timing.

This data should be able to be logged. You dont really need to tap wires but rather read data from the ECU.

 

Again, how would you do this without splicing? I don't doubt you _could_ prep the knock signal and feed it to an xede analog in. I just doubt any of us could do it any easier than buying chiptorque's....err, vishnu's knock buffer and hooking it up.

d

 

Well there is a knock sensor wire we can tap into.....people use this for AFC knock monitoring so why cant we use it without a buffer?

"The AFC's purple wire (knock sensor) should be connected to the white wire that is the 4th wire from the right on the top row of wires."

 

As freedom said, you'd have to amplify the signal to the 0-5v range that the xede uses for it's analog ins.

d

 

It really depends on the circuitry in the S-AFC. Some of the monitoring devices I tried prior to designing the knock buffer robbed the ECU of too much of the signal-- causing the car to knock terribly. Just food for thought....

shiv

 

Okay lets say its not XEDE specific........what device other than an S-AFC would be able to interpret that signal? A pocketlogger of some sort????

Also if the ECU is reading this signal.....then we should be able to optain those value directly via software shouldnt we

 

What software?

d

 

A Pocketlogger can't monitor knock directly, only ignition timing. You'd be able to see when the ECU pulled timing, and infer where the knock is, but never see the true knock value.

- Steve