Is it possible to monitor the oem knock sensor on the s2?

[Jonas_R]

I was wondering if it somehow was possible via vagcom or something similar to monitor the knock sensor?

Or is it easier to use something like knocksense?

http://www.viatrack.ca/

[|Maku|]

That's what I would like to know also! And one more question - when knock sensor detects detonation, why it doesnt immediately turn back ignition? For example, I'm using manual boost control so that boost barely drops and sometimes I hear detonation when accelerating. With second gear it may start at 4500rpm and lasts to 6500rpm. My logical thinking says that when knock sensor detects detonation danger at ca 4500 rpm, it should right away turn back the ignition. I know that one way is to lower boost pressure but do we really wanna do that?

[Rocco]

hmmm, interesting

[S2central.net]

Its just a microphone really - with good audio equipment you should be able to hear the knock sensor output... Tricky bit is the filtering required and intelligence to differentiate proper knock from all the other noise being picked up.

[JariP]

I recall somebody at motorgeek was doing this just by tapping into the knock sensor wiring and monitoring the signal with laptop and audio editing program. The knocking frequency is closely related to cylinder bore and according to some knock sensing system maker there actually aren't so many other noise sources at knock frequency in a healthy working engine. Two such sources were listed, other was valve bounce or valve clatter and the other I can't remember.

[a4kquattro]

I wrote an article/howto on my website about this. N-joy:

http://www.efiexpress.com/catalog/ar...?articles_id=4

[gnutz2]

The cheapest way is to buy an amplifier, this one works well http://www.maplin.co.uk/module.aspx?moduleno=220055
and hook it sraight up to the sensor, plug in your headphones and listen.

Or watch the signal with an oscilloscope, im not exactly sure how you read the information your getting but i know a tuner that gets good results this way.

Or like you say buy an aftermarket amplifier/ monitor but these are only really good for a warning and not much use as a tuning tool because the det has probably allready set in by the time you get the warning. The best one i have seen is phormula ks-4 http://www.phormula.co.uk/KnockMonitor-KS-4.aspx because you can set up your own gain and there is a 0-5v output for logging. But there are many others

HTH

[a4kquattro]

The cheapest way is to buy an amplifier, this one works well http://www.maplin.co.uk/module.aspx?moduleno=220055
and hook it sraight up to the sensor, plug in your headphones and listen.

Or watch the signal with an oscilloscope, im not exactly sure how you read the information your getting but i know a tuner that gets good results this way.

Or like you say buy an aftermarket amplifier/ monitor but these are only really good for a warning and not much use as a tuning tool because the det has probably allready set in by the time you get the warning. The best one i have seen is phormula ks-4 http://www.phormula.co.uk/KnockMonitor-KS-4.aspx because you can set up your own gain and there is a 0-5v output for logging. But there are many others

HTH

in my experience, no amplifier is necessary. YMMV, some of it probably depends on your microphone hardware in your pc.

[gnutz2]

So you've tried the knock sensor straight into the headphones and it works?

[a4kquattro]

So you've tried the knock sensor straight into the headphones and it works?

yes. tried on two different laptops, both ibm thinkpads (T42 and an X31). See the link I posted above for a sample audio file recorded using this setup.

[A80Avant]

marc i have emailed you about this cable!! can you please reply? i would like one made up please! thanks

[a4kquattro]

marc i have emailed you about this cable!! can you please reply? i would like one made up please! thanks

yep, this thread reminded me of your email, replying now

[quattro84]

How good is the standard laptop input channel protected? Does it have a input power protection if it catches some high power noise or is that going to smoke my motherboard?

How do you define knock? Is it easy to detect it between te rest of the noise?

What is the normal working frequency for the knocksensor? I guess same like normal piezo sensors between 1-20kHz?

What would the output voltage be like? Normal Delphi knocksensor output is really low:
Average output 27 ± 10 mV/g over 1 to 18 kHz into a 100 K Ohm resistive load



Have you measured the output signal of the knocksensor? Guess it's something like 0,5-1V.

Hmm.. i have my amplifing circuit ready with a basic filter.. i'd like to try this and log it with audio capturing software like Wavelab.. compare it to in-cilinder pressure readings in the future...

[S2central.net]

Nice article Mr Swanson

[borderS2]

Piezos

Maplin do a range of these with a variety of freq response

http://www.maplin.co.uk/module.aspx?TabID=1&criteria=usb&ModuleNo=3202&C=SO&U=Strat15

Much cheaper than a mike and can be taped in position. Work just like a mike: wire up to input on computer or amp. The output is "louder" than a guitar pickup but nowhere near line level.
Free recording software

http://audacity.sourceforge.net/

D