Anybody ever put a scope on their knock sensor?

[Jasper]

what kind of filters are needed (both frequency, and time... since knock only occurs in a certain time period for each stroke

This is called windowing.

One of the major factors leading to my purchase of an Autronic SM4 was the "fact" that it could reference the knock sensor output to the cylinder undergoing a powerstroke and provide closed loop cylinder specific knock control.

Unfortunately this feature has been "coming soon" for a over a year now

[amichie]

I have loosened and retightened my Knock sensor and got a slightly cleaner signal.
I'll have to wait and see if it makes any improvement.

My car is now running noticebly smoother. I am doing a run to Newcastle and back today and I will see how it goes and report back.

I will aslo get a price out of toyota for anew one since my signal is still a little noisy.

[1jzracing]

found some interesting info here about the general segnal

http://www.parades.rm.cnr.it/papers/...SigmaKnock.pdf

It appears as though isolating the signal is very difficult other than just listening to it which is great for interest sake but a little difficult to actually put this to use without very involved circuitry to isolate the knock from general engine noise which changes with rising rpm

there is however a slightly easier way used by the likes of the TurboXS knock light where an RPM signal is also taken by the unit and knock is seperated by any signal input over the calibrated rpm noise

this way the unit does not have to "listen" to the signal as such but just measure it and reference it against rpm to deternine if it is knock or just general noise and used in this case to energise a warning light

as a completely side issue this system may also detect oil surge around a circuit where the engine drops oil pressure and the big ends knock momentarily in mid corner which MOST cars will do without a well baffled sump

[-==L=a=N=c=E==-]

since we are on the topic of knock sensors, perhaps this will help.... Something i've been doing on the side.

http://toymods.net/forums/showpost.p...0&postcount=23

(note: its untested, but works in theory)

[1jzracing]

hey that looks pretty cool!!

let us know how it works and put me down for one if you think of selling them as a kit

or releasing a few for field testing on different engines and different conditions etc

[The Witzl]

This is called windowing.

One of the major factors leading to my purchase of an Autronic SM4 was the "fact" that it could reference the knock sensor output to the cylinder undergoing a powerstroke and provide closed loop cylinder specific knock control.

Unfortunately this feature has been "coming soon" for a over a year now

You can thank Ray Hall for claiming this knock control feature that doesnt exist yet.

[-==L=a=N=c=E==-]

hey that looks pretty cool!!

let us know how it works and put me down for one if you think of selling them as a kit

or releasing a few for field testing on different engines and different conditions etc

Well, i've been meaning to finish building it. But couldn't be bothered, and i bought a Knocklink to do the knock detecting.

This is proberbly as far as i've gone.
http://lance.ugbox.net/Hilux/Technic...knockparts.jpg
http://lance.ugbox.net/Hilux/Technic...nockpcbcut.jpg

[amichie]

So does anybody know what torque value the Knock sensor should be tightened up to???

It is not in my TSRM.

[adamaw11]

I'm sure some of you guys might know about the "super ear" kit from jaycar.
Well just yesterday I plugged my knock sensor output into my super ear as though it was an external microphone, and it worked to some extent. At idle it was sort of like the sound of busy valve train, but as rpm increases it becomes more of a static-like hiss. I went for a drive with the headphones on and there wasn't much sound difference under load.
I'm pretty sure my car wasn't pinging anyway, but I don't know whether knock would be easily human-audible with this setup so I guess I shouldn't start going nuts with ignition timing just yet

Can anyone confirm whether its pointless or not to try to hear knock directly from the knock sensor with my own ears while driving?

[Jasper]

I'm sure some of you guys might know about the "super ear" kit from jaycar.
Well just yesterday I plugged my knock sensor output into my super ear as though it was an external microphone, and it worked to some extent. At idle it was sort of like the sound of busy valve train, but as rpm increases it becomes more of a static-like hiss. I went for a drive with the headphones on and there wasn't much sound difference under load.
I'm pretty sure my car wasn't pinging anyway, but I don't know whether knock would be easily human-audible with this setup so I guess I shouldn't start going nuts with ignition timing just yet

Can anyone confirm whether its pointless or not to try to hear knock directly from the knock sensor with my own ears while driving?

http://home.people.net.au/~indecent/2006-12-23/


The .wav files at the URL above correspond to the two spectral graphs I posted earlier.

I couldn't hear it in my recordings. Do you have a laptop to record the sound for post-processing?

[amichie]

So does anybody know what torque value the Knock sensor should be tightened up to???

It is not in my TSRM.

Found a couple of web references that say 33ft.lbs

I'll give that a try.

[adamaw11]

I couldn't hear it in my recordings. Do you have a laptop to record the sound for post-processing?

Yeah I've got a laptop, I might see if i can plug it in there.

I'll give that hammer trick a go also, and see what it sounds like through headphones via the super ear

[Jasper]

Cool, remember to sample above the Nyquist frequency.

[amichie]

Found a couple of web references that say 33ft.lbs

I'll give that a try.

Torqued it up with the torque wrench yesterday.

Running very smooth. WIll report on fuel economy after a couple of tanks.

I would like to know if and how Toyota do the Automatic gain control (AGC) on the knock sensor circuit. I took the ECU apart and traced the track to an IC that was a Denso special and I couldn't find any info on it.

I know the autoshop101 site has a little info about gating etc but I don't know how they do the AGC.

ANy thoughts.

[adamaw11]

Hey Jasper, I'm guessing that Adobe Audition software isn't free is it? any chance there's alternative software that can do esentially the same thing? I noticed the free spectrum analyser on that subaru sight, just havn't been able to download it yet.

I managed to record into my laptop, tapping with hammer while engine off and while idling, and recorded driving under load. I suppose with the right sound software I'll be able to see for myself whether my 4A block also resonates close to that 6800hz frequency when tapping with a hammer and presumable while pinging also. btw I have nfi what the nyquist frequency means, I'm guessing the resonance frequency being sampled, or something in adobe audition.

pardon the questions, sorry I can't answer yours amichie.