DIY Knock Decection Autospeed style - Mazda MX-6 Forum
 
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post #1 of 9 (permalink) Old 9-13-07, 0:36 Thread Starter
 
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DIY Knock Decection Autospeed style

After reading this article Browser Warning I decided to try my hand at it.

The Whisper 2000 unit is very old and hard to find. But any WalGreens has the ListenUP personal sound amplifier for $14.95. Score!
You'll also need some speaker wire and a clamp of sorts.


First open the Listenup by prying off the side panels and undoing the four screws.


Next pull out the microphone and cut the wires. Remeber which wire is hot and gound.


Next soilder your speaker wire to the microphone and then to the wires inside the listenup. You'll want to loop the speaker wire though the housing of the case so if you drop it the speaker wire doesn't get pulled out.


Bolt the case back up and use some shrink wrap to cover those wires.


Now with the mic use some hot glue to glue it to the end of the clamp. Use electrical tape to hold it all together, once again loop the speaker wire so the mic doesn't get damaged.


If yours doesn't look like this you did something wrong.


To use simple place it on the block where a knock sensor would go and go out and drive.


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post #2 of 9 (permalink) Old 9-22-07, 0:27

 
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You should use a shielded coax for the cable
Its going to pick up ever ignition and injector noise close to it.

Is this a Joke BTW?
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post #3 of 9 (permalink) Old 9-22-07, 0:37
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I would just as well use the wires off of the KS and hook those up to a small light or LED of somesort. This is how to test for to see if it's working, per the manual.

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post #4 of 9 (permalink) Old 9-22-07, 2:47 Thread Starter
 
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Quote:
Originally Posted by LARKEN View Post
You should use a shielded coax for the cable
Its going to pick up ever ignition and injector noise close to it.

Is this a Joke BTW?
No its not a joke. You don't need shield coax for it to work right. That it for what it is. Its a small mic hooked to a small amp so you can "hear" engine knock. Last I checked my injectors and ignition are not mounted next to my knock sensor. Try it for your self it works pretty well.

The lights don't work well if you don't know what its calibrated for. Its much slower than listening to the engine.

Read the autospeed article.

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post #5 of 9 (permalink) Old 9-23-07, 0:08

 
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Did you find where you put the mike on the block makes a difference in sound?
A graphic eq would be good to filter the sound.

Quote:
You don't need shield coax for it to work right.
BTW, In the article it shows using shielded cable, otherwise you will be amplifing noise.

Interesting project though.

Last edited by LARKEN; 9-23-07 at 0:13.
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post #6 of 9 (permalink) Old 9-27-07, 16:05
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Taking the subject a bit further, I wonder if it would offer any usable data to run the engine noise into a FFT/spectrum analyzer? As I remember, the traditional knock sensing is just listening if the noise goes above certain, RPM-based limit, effectively cutting down the chances to detect knock at higher RPM. An oscilloscope with FFT capabilities could tell if there's distinct patterns to the pinging, and detect them through overwhelming engine noise.

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post #7 of 9 (permalink) Old 9-27-07, 20:04
 
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Quote:
Originally Posted by STW View Post
Taking the subject a bit further, I wonder if it would offer any usable data to run the engine noise into a FFT/spectrum analyzer? As I remember, the traditional knock sensing is just listening if the noise goes above certain, RPM-based limit, effectively cutting down the chances to detect knock at higher RPM. An oscilloscope with FFT capabilities could tell if there's distinct patterns to the pinging, and detect them through overwhelming engine noise.
smart thinking.

recording this to a pc as a sound file could provide some interesting info when filtered...

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post #8 of 9 (permalink) Old 12-14-08, 18:59
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You can do the same if not better (be ear) by using a vacuum line and a stethoscope into the passenger compartment. The F2 intake manifolds have a plug for a temp sensor that you can use and hear all noise in the head rather than electronic static and crap outside (interference). Granted, with a stethoscope the only way to record it is with your dome piece.



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post #9 of 9 (permalink) Old 12-14-08, 19:01
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Quote:
Originally Posted by SixSick6 View Post
You can do the same if not better (be ear) by using a vacuum line and a stethoscope into the passenger compartment. The F2 intake manifolds have a plug for a temp sensor that you can use and hear all noise in the head rather than electronic static and crap outside (interference). Granted, with a stethoscope the only way to record it is with your dome piece.
I'm there is a device that can be input into your laptop to record the audio.

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