imitek

just wanted some info on it
And how much knock people run
In ideal world 0 knock
Voltages is my main worry thanks

Vicoor

Not really sure exactly what you are asking.

The knock sensor is essentially a piezoelectric microphone. The knock sensor signal is processed by a somewhat complicated filter circuit that the ecu monitors for "noise" in a certain frequency range (3.5khz?) and once that exceeds a certain threshold, the ECU "determines" that knock is occurring and takes action to reduce it.

I don't think there is a voltage value that you could measure.

imitek

Thanks for your reply I thort the knock sensor generates its own voltage
I have not done any testing yet this is why i ask evry 1 first my idea may fall threw lol
i wanted to make a knock tester for my car

Vicoor

Technically speaking it is a voltage, but it's more like an audio signal.

You can use an audio amplifier to listen for knock with the knock sensor signal. I think you'd want to use a "wideband" knock sensor though. If you do a web search you can find some info about this.

imitek

Intresting so if i had an aux in on my sterio i could just hook it to that ?

Vicoor

I haven't done this yet, but I do plan to.

So, I don't know if you'd be able to hear the knock over the stereo due to all the ambient noise that's happening in the car. There are professional "Knock Ears" available. These use a standalone amplifier and headphones.

Also, consider your ability to identify the knock, and be honest with yourself. I'm an automotive technician with over 30 years experience. I've experienced knock on lots of cars, in lots of different situations. So I have a very high degree of confidence in my ability to identify knock. Remember, if you get it wrong, you may kill an engine.


I'd say spend some time researching this. If you really dig around there are some decent bits of info here and there.

t-von

iTrader: (8)

^Hmm your aux audio idea is giving me one also. How come knowone has built a knock level gauge? It could rotate just like a tachometer to give you real time reference of actuall knock with a green, yellow, and red zones? It should also have some built in safegaurds.

Vicoor

not quite what you are talking about, but, has display

KS-3 Knock Detection and Engine Tuning Systems

t-von

iTrader: (8)

^ I think we need more variations of these. I dont like bulky box like assesories all over my dash. A nice small round gauge or even better, incorporating a duel needle gauge with a boost gauge would work and save room. It doesn't need to be all fancy. Plx devices could easily do this with their multi guage display.

Vicoor

Well, get on it, and design something!

imitek

My oridginal plan was to just hook the sensor up to a voltage meter in the car thats why i asked what voltage is a real knock seemed like the easyest method
And hook up the det cans to determin a real knock then see the voltage

j9fd3s

iTrader: (3)

its a frequency, its a noise. https://www.rx7club.com/general-rota...ensor-1026792/

jetlude

iTrader: (9)

I have tried this, but I used a sound recorder program on my PC. The program had the ability to filter specific frequencies. I cant say that I have had much luck though. As another poster said I is difficult to tell knock apart from other noises.
Plan on continuing experimenting with it.

t-von

iTrader: (8)

I'll leave that to the company's that build gauges for a living. I'm too busy with my own specialized engine projects.

mdp

Everything old is new again, here is probably the most complete explanation of rotary knock and the sensor.

imitek

Any chance uploading a recordording

Vicoor

^^^^
What he said!

Sideo

great post! From what ive read it sounds like knock is generally in the 6500-7k hz frequency you could probably get a data aquisition box, a laptop, labview, run a bandpass filter and get an idea of knock but that is also a lot of work...

7krayziboi

iTrader: (15)

The KS-3 Knock Detection looks great but
Don't we want 2 knock sensors ? (For each housing)

I like the idea of a gauge with safeguard