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Old 06-14-2007, 06:33 PM   #1
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Default DIY knock detecting tool

So a friend of mine that runs a shop in town shows me the inside of his cifvic the othere day, I look inside and find a stethascope on his console thats connected to a tube running under the firewall.
"What's that for?" I asked. He says, "Oh, it's a det-can, I use it to listen for knock when I'm driving and tuning"
I couldn't believe it, all it was was a stethascope, some plastic hose, and a copper pipe hooked on to the block, and you can hear the internals perfectly. Worked so good I put one in my WRX and detected knock that my knock sensor didn't pick up.
Anyone heard of this or want to know more? If this is new to some people I might do a DIY write-up on it soon.
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Old 06-14-2007, 06:51 PM   #2
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I have one sorta like that. Only mine is a microphone from one of those cheap *** spy thingys that amplifies nearby sounds. I superglued it to a clamp from an old pair or jumper cables. I just listen to knock through headphones.

Funny thing is that I wasn't using them when my motor blew :(
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Old 06-14-2007, 06:53 PM   #3
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Funny thing is that I wasn't using them when my motor blew :(

Doh! Knock sensor FTW!
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Old 06-14-2007, 07:41 PM   #4
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I might try this.
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Old 06-14-2007, 07:48 PM   #5
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That's "old school". I've seen my dad do that many times.
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Old 06-14-2007, 08:39 PM   #6
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Question is, what are you doing to control the knock?

Cool trick,btw.
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Old 06-14-2007, 09:01 PM   #7
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you let off the gas, thats how. With this method you will hear knock before a knock sensor would even pick up on it. Ears = more sensitive than knock sensor.
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Old 06-14-2007, 09:01 PM   #8
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Lifting noting, and fixing it later, or tweaking the ECU duh
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Old 06-14-2007, 09:29 PM   #9
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I guess I didn't answer his question all the way.

It is simply a tuning tool, not something you keep on the car all the time.
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Old 06-15-2007, 02:21 AM   #10
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That Is pretty cool, i might hook up something like this when I get the car back on the road
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Old 06-15-2007, 02:40 AM   #11
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My dad has something like this as well. He has another tool that has a solid rod probe at the other end. If you have some kind of engine noise you can stick that probe on different parts of the motor too find out where it's coming from. Kind of like using a vac line to find air leaks, you use the probe to find mechanical noise.
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Old 06-15-2007, 03:34 AM   #12
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Long screwdriver up to the ear works too
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Old 06-15-2007, 03:56 AM   #13
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Quote:
Originally Posted by akaryrye View Post
Long screwdriver up to the ear works too
Same idea Def more readily available.
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Old 06-15-2007, 11:09 AM   #14
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I use an electronic version. Find a typical bosch knock sensor, get an obd1 injector plug.. or keep the plug from the sensor and splice it into a stereo jack cable. Buy a cheap little amp/speaker unit from radiashack and use that or headphones from it.

I can hear the fuel priming in the rail at startup.... its awesome.
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Old 06-15-2007, 05:41 PM   #15
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Quote:
Originally Posted by cjernigan View Post
My dad has something like this as well. He has another tool that has a solid rod probe at the other end. If you have some kind of engine noise you can stick that probe on different parts of the motor too find out where it's coming from. Kind of like using a vac line to find air leaks, you use the probe to find mechanical noise.

I used the stethascope end from that same thing. I got it at autozone. The great thing about the setup I'm using is that you can use it when the car is moving.
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Old 06-16-2007, 07:00 PM   #16
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Quote:
Originally Posted by akaryrye View Post
Long screwdriver up to the ear works too
I'd like to see that in use during a boost run
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